validation

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 Go to latest Published: Jul 30, 2024 License: MIT Imports: 14 Imported by: 61

README

Go Validation

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NOTE: This is a fork of the well known ozzo-validation package which as of Feb 2023 doesn't appear to be under active maintenance for more than 2 years. At Invopop we use this library extensively, so it only felt appropriate to be more pro-active. We'll do out best to respond to issues and review or merge any pull requests.

Description

validation is a Go package that provides configurable and extensible data validation capabilities.

It has the following features:

  • use normal programming constructs rather than error-prone struct tags to specify how data should be validated.
  • can validate data of different types, e.g., structs, strings, byte slices, slices, maps, arrays.
  • can validate custom data types as long as they implement the Validatable interface.
  • can validate data types that implement the sql.Valuer interface (e.g. sql.NullString).
  • customizable and well-formatted validation errors.
  • error code and message translation support.
  • provide a rich set of validation rules right out of box.
  • extremely easy to create and use custom validation rules.

For an example on how this library is used in an application, please refer to go-rest-api which is a starter kit for building RESTful APIs in Go.

For further examples, checkout the GOBL project which uses validation extensively.

Requirements

Go 1.16 or above.

Getting Started

The validation package mainly includes a set of validation rules and two validation methods. You use validation rules to describe how a value should be considered valid, and you call either validation.Validate() or validation.ValidateStruct() to validate the value.

Installation

Run the following command to install the package:

go get github.com/invopop/validation
Validating a Simple Value

For a simple value, such as a string or an integer, you may use validation.Validate() to validate it. For example,

package main

import (
	"fmt"

	"github.com/invopop/validation"
	"github.com/invopop/validation/is"
)

func main() {
	data := "example"
	err := validation.Validate(data,
		validation.Required,       // not empty
		validation.Length(5, 100), // length between 5 and 100
		is.URL,                    // is a valid URL
	)
	fmt.Println(err)
	// Output:
	// must be a valid URL
}

The method validation.Validate() will run through the rules in the order that they are listed. If a rule fails the validation, the method will return the corresponding error and skip the rest of the rules. The method will return nil if the value passes all validation rules.

Validating a Struct

For a struct value, you usually want to check if its fields are valid. For example, in a RESTful application, you may unmarshal the request payload into a struct and then validate the struct fields. If one or multiple fields are invalid, you may want to get an error describing which fields are invalid. You can use validation.ValidateStruct() to achieve this purpose. A single struct can have rules for multiple fields, and a field can be associated with multiple rules. For example,

type Address struct {
	Street string
	City   string
	State  string
	Zip    string
}

func (a Address) Validate() error {
	return validation.ValidateStruct(&a,
		// Street cannot be empty, and the length must between 2 and 50
		validation.Field(&a.Street, validation.Required, validation.Length(2, 50)),
		// City cannot be empty, and the length must between 2 and 50
		validation.Field(&a.City, validation.Required, validation.Length(2, 50)),
		// State cannot be empty, and must be a string consisting of two letters in upper case
		validation.Field(&a.State, validation.Required, validation.Match(regexp.MustCompile("^[A-Z]{2}$"))),
		// State cannot be empty, and must be a string consisting of five digits
		validation.Field(&a.Zip, validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
	)
}

a := Address{
    Street: "123",
    City:   "Unknown",
    State:  "Virginia",
    Zip:    "12345",
}

err := a.Validate()
fmt.Println(err)
// Output:
// Street: the length must be between 5 and 50; State: must be in a valid format.

Note that when calling validation.ValidateStruct to validate a struct, you should pass to the method a pointer to the struct instead of the struct itself. Similarly, when calling validation.Field to specify the rules for a struct field, you should use a pointer to the struct field.

When the struct validation is performed, the fields are validated in the order they are specified in ValidateStruct. And when each field is validated, its rules are also evaluated in the order they are associated with the field. If a rule fails, an error is recorded for that field, and the validation will continue with the next field.

Validating a Map

Sometimes you might need to work with dynamic data stored in maps rather than a typed model. You can use validation.Map() in this situation. A single map can have rules for multiple keys, and a key can be associated with multiple rules. For example,

c := map[string]interface{}{
	"Name":  "Qiang Xue",
	"Email": "q",
	"Address": map[string]interface{}{
		"Street": "123",
		"City":   "Unknown",
		"State":  "Virginia",
		"Zip":    "12345",
	},
}

err := validation.Validate(c,
	validation.Map(
		// Name cannot be empty, and the length must be between 5 and 20.
		validation.Key("Name", validation.Required, validation.Length(5, 20)),
		// Email cannot be empty and should be in a valid email format.
		validation.Key("Email", validation.Required, is.Email),
		// Validate Address using its own validation rules
		validation.Key("Address", validation.Map(
			// Street cannot be empty, and the length must between 2 and 50
			validation.Key("Street", validation.Required, validation.Length(2, 50)),
			// City cannot be empty, and the length must between 2 and 50
			validation.Key("City", validation.Required, validation.Length(2, 50)),
			// State cannot be empty, and must be a string consisting of two letters in upper case
			validation.Key("State", validation.Required, validation.Match(regexp.MustCompile("^[A-Z]{2}$"))),
			// State cannot be empty, and must be a string consisting of five digits
			validation.Key("Zip", validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
		)),
	),
)
fmt.Println(err)
// Output:
// Address: (State: must be in a valid format; Street: the length must be between 5 and 50.); Email: must be a valid email address.

When the map validation is performed, the keys are validated in the order they are specified in Map. And when each key is validated, its rules are also evaluated in the order they are associated with the key. If a rule fails, an error is recorded for that key, and the validation will continue with the next key.

Validation Errors

The validation.ValidateStruct method returns validation errors found in struct fields in terms of validation.Errors which is a map of fields and their corresponding errors. Nil is returned if validation passes.

By default, validation.Errors uses the struct tags named json to determine what names should be used to represent the invalid fields. The type also implements the json.Marshaler interface so that it can be marshaled into a proper JSON object. For example,

type Address struct {
	Street string `json:"street"`
	City   string `json:"city"`
	State  string `json:"state"`
	Zip    string `json:"zip"`
}

// ...perform validation here...

err := a.Validate()
b, _ := json.Marshal(err)
fmt.Println(string(b))
// Output:
// {"street":"the length must be between 5 and 50","state":"must be in a valid format"}

You may modify validation.ErrorTag to use a different struct tag name.

If you do not like the magic that ValidateStruct determines error keys based on struct field names or corresponding tag values, you may use the following alternative approach:

c := Customer{
	Name:  "Qiang Xue",
	Email: "q",
	Address: Address{
		State:  "Virginia",
	},
}

err := validation.Errors{
	"name": validation.Validate(c.Name, validation.Required, validation.Length(5, 20)),
	"email": validation.Validate(c.Name, validation.Required, is.Email),
	"zip": validation.Validate(c.Address.Zip, validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
}.Filter()
fmt.Println(err)
// Output:
// email: must be a valid email address; zip: cannot be blank.

In the above example, we build a validation.Errors by a list of names and the corresponding validation results. At the end we call Errors.Filter() to remove from Errors all nils which correspond to those successful validation results. The method will return nil if Errors is empty.

The above approach is very flexible as it allows you to freely build up your validation error structure. You can use it to validate both struct and non-struct values. Compared to using ValidateStruct to validate a struct, it has the drawback that you have to redundantly specify the error keys while ValidateStruct can automatically find them out.

Internal Errors

Internal errors are different from validation errors in that internal errors are caused by malfunctioning code (e.g. a validator making a remote call to validate some data when the remote service is down) rather than the data being validated. When an internal error happens during data validation, you may allow the user to resubmit the same data to perform validation again, hoping the program resumes functioning. On the other hand, if data validation fails due to data error, the user should generally not resubmit the same data again.

To differentiate internal errors from validation errors, when an internal error occurs in a validator, wrap it into validation.InternalError by calling validation.NewInternalError(). The user of the validator can then check if a returned error is an internal error or not. For example,

if err := a.Validate(); err != nil {
	if e, ok := err.(validation.InternalError); ok {
		// an internal error happened
		fmt.Println(e.InternalError())
	}
}

Validatable Types

A type is validatable if it implements the validation.Validatable interface.

When validation.Validate is used to validate a validatable value, if it does not find any error with the given validation rules, it will further call the value's Validate() method.

Similarly, when validation.ValidateStruct is validating a struct field whose type is validatable, it will call the field's Validate method after it passes the listed rules.

Note: When implementing validation.Validatable, do not call validation.Validate() to validate the value in its original type because this will cause infinite loops. For example, if you define a new type MyString as string and implement validation.Validatable for MyString, within the Validate() function you should cast the value to string first before calling validation.Validate() to validate it.

In the following example, the Address field of Customer is validatable because Address implements validation.Validatable. Therefore, when validating a Customer struct with validation.ValidateStruct, validation will "dive" into the Address field.

type Customer struct {
	Name    string
	Gender  string
	Email   string
	Address Address
}

func (c Customer) Validate() error {
	return validation.ValidateStruct(&c,
		// Name cannot be empty, and the length must be between 5 and 20.
		validation.Field(&c.Name, validation.Required, validation.Length(5, 20)),
		// Gender is optional, and should be either "Female" or "Male".
		validation.Field(&c.Gender, validation.In("Female", "Male")),
		// Email cannot be empty and should be in a valid email format.
		validation.Field(&c.Email, validation.Required, is.Email),
		// Validate Address using its own validation rules
		validation.Field(&c.Address),
	)
}

c := Customer{
	Name:  "Qiang Xue",
	Email: "q",
	Address: Address{
		Street: "123 Main Street",
		City:   "Unknown",
		State:  "Virginia",
		Zip:    "12345",
	},
}

err := c.Validate()
fmt.Println(err)
// Output:
// Address: (State: must be in a valid format.); Email: must be a valid email address.

Sometimes, you may want to skip the invocation of a type's Validate method. To do so, simply associate a validation.Skip rule with the value being validated.

Maps/Slices/Arrays of Validatables

When validating an iterable (map, slice, or array), whose element type implements the validation.Validatable interface, the validation.Validate method will call the Validate method of every non-nil element. The validation errors of the elements will be returned as validation.Errors which maps the keys of the invalid elements to their corresponding validation errors. For example,

addresses := []Address{
	Address{State: "MD", Zip: "12345"},
	Address{Street: "123 Main St", City: "Vienna", State: "VA", Zip: "12345"},
	Address{City: "Unknown", State: "NC", Zip: "123"},
}
err := validation.Validate(addresses)
fmt.Println(err)
// Output:
// 0: (City: cannot be blank; Street: cannot be blank.); 2: (Street: cannot be blank; Zip: must be in a valid format.).

When using validation.ValidateStruct to validate a struct, the above validation procedure also applies to those struct fields which are map/slices/arrays of validatables.

Each

The Each validation rule allows you to apply a set of rules to each element of an array, slice, or map.

type Customer struct {
    Name      string
    Emails    []string
}

func (c Customer) Validate() error {
    return validation.ValidateStruct(&c,
        // Name cannot be empty, and the length must be between 5 and 20.
		validation.Field(&c.Name, validation.Required, validation.Length(5, 20)),
		// Emails are optional, but if given must be valid.
		validation.Field(&c.Emails, validation.Each(is.Email)),
    )
}

c := Customer{
    Name:   "Qiang Xue",
    Emails: []Email{
        "valid@example.com",
        "invalid",
    },
}

err := c.Validate()
fmt.Println(err)
// Output:
// Emails: (1: must be a valid email address.).
Pointers

When a value being validated is a pointer, most validation rules will validate the actual value pointed to by the pointer. If the pointer is nil, these rules will skip the validation.

An exception is the validation.Required and validation.NotNil rules. When a pointer is nil, they will report a validation error.

Types Implementing sql.Valuer

If a data type implements the sql.Valuer interface (e.g. sql.NullString), the built-in validation rules will handle it properly. In particular, when a rule is validating such data, it will call the Value() method and validate the returned value instead.

Required vs. Not Nil

When validating input values, there are two different scenarios about checking if input values are provided or not.

In the first scenario, an input value is considered missing if it is not entered or it is entered as a zero value (e.g. an empty string, a zero integer). You can use the validation.Required rule in this case.

In the second scenario, an input value is considered missing only if it is not entered. A pointer field is usually used in this case so that you can detect if a value is entered or not by checking if the pointer is nil or not. You can use the validation.NotNil rule to ensure a value is entered (even if it is a zero value).

Embedded Structs

The validation.ValidateStruct method will properly validate a struct that contains embedded structs. In particular, the fields of an embedded struct are treated as if they belong directly to the containing struct. For example,

type Employee struct {
	Name string
}

type Manager struct {
	Employee
	Level int
}

m := Manager{}
err := validation.ValidateStruct(&m,
	validation.Field(&m.Name, validation.Required),
	validation.Field(&m.Level, validation.Required),
)
fmt.Println(err)
// Output:
// Level: cannot be blank; Name: cannot be blank.

In the above code, we use &m.Name to specify the validation of the Name field of the embedded struct Employee. And the validation error uses Name as the key for the error associated with the Name field as if Name a field directly belonging to Manager.

If Employee implements the validation.Validatable interface, we can also use the following code to validate Manager, which generates the same validation result:

func (e Employee) Validate() error {
	return validation.ValidateStruct(&e,
		validation.Field(&e.Name, validation.Required),
	)
}

err := validation.ValidateStruct(&m,
	validation.Field(&m.Employee),
	validation.Field(&m.Level, validation.Required),
)
fmt.Println(err)
// Output:
// Level: cannot be blank; Name: cannot be blank.
Conditional Validation

Sometimes, we may want to validate a value only when certain condition is met. For example, we want to ensure the unit struct field is not empty only when the quantity field is not empty; or we may want to ensure either email or phone is provided. The so-called conditional validation can be achieved with the help of validation.When. The following code implements the aforementioned examples:

result := validation.ValidateStruct(&a,
    validation.Field(&a.Unit, validation.When(a.Quantity != "", validation.Required).Else(validation.Nil)),
    validation.Field(&a.Phone, validation.When(a.Email == "", validation.Required.Error("Either phone or Email is required.")),
    validation.Field(&a.Email, validation.When(a.Phone == "", validation.Required.Error("Either phone or Email is required.")),
)

Note that validation.When and validation.When.Else can take a list of validation rules. These rules will be executed only when the condition is true (When) or false (Else).

The above code can also be simplified using the shortcut validation.Required.When:

result := validation.ValidateStruct(&a,
    validation.Field(&a.Unit, validation.Required.When(a.Quantity != ""), validation.Nil.When(a.Quantity == "")),
    validation.Field(&a.Phone, validation.Required.When(a.Email == "").Error("Either phone or Email is required.")),
    validation.Field(&a.Email, validation.Required.When(a.Phone == "").Error("Either phone or Email is required.")),
)
Customizing Error Messages

All built-in validation rules allow you to customize their error messages. To do so, simply call the Error() method of the rules. For example,

data := "2123"
err := validation.Validate(data,
	validation.Required.Error("is required"),
	validation.Match(regexp.MustCompile("^[0-9]{5}$")).Error("must be a string with five digits"),
)
fmt.Println(err)
// Output:
// must be a string with five digits

You can also customize the pre-defined error(s) of a built-in rule such that the customization applies to every instance of the rule. For example, the Required rule uses the pre-defined error ErrRequired. You can customize it during the application initialization:

validation.ErrRequired = validation.ErrRequired.SetMessage("the value is required")
Error Code and Message Translation

The errors returned by the validation rules implement the Error interface which contains the Code() method to provide the error code information. While the message of a validation error is often customized, the code is immutable. You can use error code to programmatically check a validation error or look for the translation of the corresponding message.

If you are developing your own validation rules, you can use validation.NewError() to create a validation error which implements the aforementioned Error interface.

Creating Custom Rules

Creating a custom rule is as simple as implementing the validation.Rule interface. The interface contains a single method as shown below, which should validate the value and return the validation error, if any:

// Validate validates a value and returns an error if validation fails.
Validate(value interface{}) error

If you already have a function with the same signature as shown above, you can call validation.By() to turn it into a validation rule. For example,

func checkAbc(value interface{}) error {
	s, _ := value.(string)
	if s != "abc" {
		return errors.New("must be abc")
	}
	return nil
}

err := validation.Validate("xyz", validation.By(checkAbc))
fmt.Println(err)
// Output: must be abc

If your validation function takes additional parameters, you can use the following closure trick:

func stringEquals(str string) validation.RuleFunc {
	return func(value interface{}) error {
		s, _ := value.(string)
        if s != str {
            return errors.New("unexpected string")
        }
        return nil
    }
}

err := validation.Validate("xyz", validation.By(stringEquals("abc")))
fmt.Println(err)
// Output: unexpected string
Rule Groups

When a combination of several rules are used in multiple places, you may use the following trick to create a rule group so that your code is more maintainable.

var NameRule = []validation.Rule{
	validation.Required,
	validation.Length(5, 20),
}

type User struct {
	FirstName string
	LastName  string
}

func (u User) Validate() error {
	return validation.ValidateStruct(&u,
		validation.Field(&u.FirstName, NameRule...),
		validation.Field(&u.LastName, NameRule...),
	)
}

In the above example, we create a rule group NameRule which consists of two validation rules. We then use this rule group to validate both FirstName and LastName.

Context-aware Validation

While most validation rules are self-contained, some rules may depend dynamically on a context. A rule may implement the validation.RuleWithContext interface to support the so-called context-aware validation.

To validate an arbitrary value with a context, call validation.ValidateWithContext(). The context.Conext parameter will be passed along to those rules that implement validation.RuleWithContext.

To validate the fields of a struct with a context, call validation.ValidateStructWithContext().

You can define a context-aware rule from scratch by implementing both validation.Rule and validation.RuleWithContext. You can also use validation.WithContext() to turn a function into a context-aware rule. For example,

rule := validation.WithContext(func(ctx context.Context, value interface{}) error {
	if ctx.Value("secret") == value.(string) {
	    return nil
	}
	return errors.New("value incorrect")
})
value := "xyz"
ctx := context.WithValue(context.Background(), "secret", "example")
err := validation.ValidateWithContext(ctx, value, rule)
fmt.Println(err)
// Output: value incorrect

When performing context-aware validation, if a rule does not implement validation.RuleWithContext, its validation.Rule will be used instead.

Built-in Validation Rules

The following rules are provided in the validation package:

  • In[T any](values ...T): checks if a value can be found in the given list of values.
  • NotIn[T any](values ...T): checks if a value is NOT among the given list of values.
  • Length(min, max int): checks if the length of a value is within the specified range. This rule should only be used for validating strings, slices, maps, and arrays.
  • RuneLength(min, max int): checks if the length of a string is within the specified range. This rule is similar as Length except that when the value being validated is a string, it checks its rune length instead of byte length.
  • Min(min any) and Max(max any): checks if a value is within the specified range. These two rules should only be used for validating int, uint, float and time.Time types.
  • Match(*regexp.Regexp): checks if a value matches the specified regular expression. This rule should only be used for strings and byte slices.
  • Date(layout string): checks if a string value is a date whose format is specified by the layout. By calling Min() and/or Max(), you can check additionally if the date is within the specified range.
  • Required: checks if a value is not empty (neither nil nor zero).
  • NotNil: checks if a pointer value is not nil. Non-pointer values are considered valid.
  • NilOrNotEmpty: checks if a value is a nil pointer or a non-empty value. This differs from Required in that it treats a nil pointer as valid.
  • Nil: checks if a value is a nil pointer.
  • Empty: checks if a value is empty. nil pointers are considered valid.
  • Skip: this is a special rule used to indicate that all rules following it should be skipped (including the nested ones).
  • MultipleOf: checks if the value is a multiple of the specified range.
  • Each(rules ...Rule): checks the elements within an iterable (map/slice/array) with other rules.
  • When(condition, rules ...Rule): validates with the specified rules only when the condition is true.
  • Else(rules ...Rule): must be used with When(condition, rules ...Rule), validates with the specified rules only when the condition is false.

The is sub-package provides a list of commonly used string validation rules that can be used to check if the format of a value satisfies certain requirements. Note that these rules only handle strings and byte slices and if a string or byte slice is empty, it is considered valid. You may use a Required rule to ensure a value is not empty. Below is the whole list of the rules provided by the is package:

  • Email: validates if a string is an email or not. It also checks if the MX record exists for the email domain.
  • EmailFormat: validates if a string is an email or not. It does NOT check the existence of the MX record.
  • URL: validates if a string is a valid URL
  • RequestURL: validates if a string is a valid request URL
  • RequestURI: validates if a string is a valid request URI
  • Alpha: validates if a string contains English letters only (a-zA-Z)
  • Digit: validates if a string contains digits only (0-9)
  • Alphanumeric: validates if a string contains English letters and digits only (a-zA-Z0-9)
  • UTFLetter: validates if a string contains unicode letters only
  • UTFDigit: validates if a string contains unicode decimal digits only
  • UTFLetterNumeric: validates if a string contains unicode letters and numbers only
  • UTFNumeric: validates if a string contains unicode number characters (category N) only
  • LowerCase: validates if a string contains lower case unicode letters only
  • UpperCase: validates if a string contains upper case unicode letters only
  • Hexadecimal: validates if a string is a valid hexadecimal number
  • HexColor: validates if a string is a valid hexadecimal color code
  • RGBColor: validates if a string is a valid RGB color in the form of rgb(R, G, B)
  • Int: validates if a string is a valid integer number
  • Float: validates if a string is a floating point number
  • UUIDv3: validates if a string is a valid version 3 UUID
  • UUIDv4: validates if a string is a valid version 4 UUID
  • UUIDv5: validates if a string is a valid version 5 UUID
  • UUID: validates if a string is a valid UUID
  • ULID: validates if a string is a valid ULID
  • CreditCard: validates if a string is a valid credit card number
  • ISBN10: validates if a string is an ISBN version 10
  • ISBN13: validates if a string is an ISBN version 13
  • ISBN: validates if a string is an ISBN (either version 10 or 13)
  • JSON: validates if a string is in valid JSON format
  • ASCII: validates if a string contains ASCII characters only
  • PrintableASCII: validates if a string contains printable ASCII characters only
  • Multibyte: validates if a string contains multibyte characters
  • FullWidth: validates if a string contains full-width characters
  • HalfWidth: validates if a string contains half-width characters
  • VariableWidth: validates if a string contains both full-width and half-width characters
  • Base64: validates if a string is encoded in Base64
  • DataURI: validates if a string is a valid base64-encoded data URI
  • E164: validates if a string is a valid E164 phone number (+19251232233)
  • CountryCode2: validates if a string is a valid ISO3166 Alpha 2 country code
  • CountryCode3: validates if a string is a valid ISO3166 Alpha 3 country code
  • DialString: validates if a string is a valid dial string that can be passed to Dial()
  • MAC: validates if a string is a MAC address
  • IP: validates if a string is a valid IP address (either version 4 or 6)
  • IPv4: validates if a string is a valid version 4 IP address
  • IPv6: validates if a string is a valid version 6 IP address
  • Subdomain: validates if a string is valid subdomain
  • Domain: validates if a string is valid domain
  • DNSName: validates if a string is valid DNS name
  • Host: validates if a string is a valid IP (both v4 and v6) or a valid DNS name
  • Port: validates if a string is a valid port number
  • MongoID: validates if a string is a valid Mongo ID
  • Latitude: validates if a string is a valid latitude
  • Longitude: validates if a string is a valid longitude
  • SSN: validates if a string is a social security number (SSN)
  • Semver: validates if a string is a valid semantic version

Credits

The is sub-package wraps the excellent validators provided by the govalidator package.

Documentation

Overview

Package validation provides configurable and extensible rules for validating data of various types.

Example 
package main

import (
	"fmt"
	"regexp"

	"github.com/invopop/validation"
	"github.com/invopop/validation/is"
)

type Address struct {
	Street string
	City   string
	State  string
	Zip    string
}

type Customer struct {
	Name    string
	Gender  string
	Email   string
	Address Address
}

func (a Address) Validate() error {
	return validation.ValidateStruct(&a,

		validation.Field(&a.Street, validation.Required, validation.Length(5, 50)),

		validation.Field(&a.City, validation.Required, validation.Length(5, 50)),

		validation.Field(&a.State, validation.Required, validation.Match(regexp.MustCompile("^[A-Z]{2}$"))),

		validation.Field(&a.Zip, validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
	)
}

func (c Customer) Validate() error {
	return validation.ValidateStruct(&c,

		validation.Field(&c.Name, validation.Required, validation.Length(5, 20)),

		validation.Field(&c.Gender, validation.In("Female", "Male")),

		validation.Field(&c.Email, validation.Required, is.Email),

		validation.Field(&c.Address),
	)
}

func main() {
	c := Customer{
		Name:  "Qiang Xue",
		Email: "q",
		Address: Address{
			Street: "123 Main Street",
			City:   "Unknown",
			State:  "Virginia",
			Zip:    "12345",
		},
	}

	err := c.Validate()
	fmt.Println(err)
}

Output:

Address: (State: must be in a valid format.); Email: must be a valid email address.
Example (Five) 
package main

import (
	"fmt"

	"github.com/invopop/validation"
)

func main() {
	type Employee struct {
		Name string
	}

	type Manager struct {
		Employee
		Level int
	}

	m := Manager{}
	err := validation.ValidateStruct(&m,
		validation.Field(&m.Name, validation.Required),
		validation.Field(&m.Level, validation.Required),
	)
	fmt.Println(err)
}

Output:

Level: cannot be blank; Name: cannot be blank.
Example (Four) 
package main

import (
	"fmt"
	"regexp"

	"github.com/invopop/validation"
	"github.com/invopop/validation/is"
)

type Address struct {
	Street string
	City   string
	State  string
	Zip    string
}

type Customer struct {
	Name    string
	Gender  string
	Email   string
	Address Address
}

func (a Address) Validate() error {
	return validation.ValidateStruct(&a,

		validation.Field(&a.Street, validation.Required, validation.Length(5, 50)),

		validation.Field(&a.City, validation.Required, validation.Length(5, 50)),

		validation.Field(&a.State, validation.Required, validation.Match(regexp.MustCompile("^[A-Z]{2}$"))),

		validation.Field(&a.Zip, validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
	)
}

func (c Customer) Validate() error {
	return validation.ValidateStruct(&c,

		validation.Field(&c.Name, validation.Required, validation.Length(5, 20)),

		validation.Field(&c.Gender, validation.In("Female", "Male")),

		validation.Field(&c.Email, validation.Required, is.Email),

		validation.Field(&c.Address),
	)
}

func main() {
	c := Customer{
		Name:  "Qiang Xue",
		Email: "q",
		Address: Address{
			State: "Virginia",
		},
	}

	err := validation.Errors{
		"name":  validation.Validate(c.Name, validation.Required, validation.Length(5, 20)),
		"email": validation.Validate(c.Name, validation.Required, is.Email),
		"zip":   validation.Validate(c.Address.Zip, validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
	}.Filter()
	fmt.Println(err)
}

Output:

email: must be a valid email address; zip: cannot be blank.
Example (Second) 
package main

import (
	"fmt"

	"github.com/invopop/validation"
	"github.com/invopop/validation/is"
)

func main() {
	data := "example"
	err := validation.Validate(data,
		validation.Required,       // not empty
		validation.Length(5, 100), // length between 5 and 100
		is.URL,                    // is a valid URL
	)
	fmt.Println(err)
}

Output:

must be a valid URL
Example (Seven) 
package main

import (
	"fmt"
	"regexp"

	"github.com/invopop/validation"
	"github.com/invopop/validation/is"
)

func main() {
	c := map[string]interface{}{
		"Name":  "Qiang Xue",
		"Email": "q",
		"Address": map[string]interface{}{
			"Street": "123",
			"City":   "Unknown",
			"State":  "Virginia",
			"Zip":    "12345",
		},
	}

	err := validation.Validate(c,
		validation.Map(
			// Name cannot be empty, and the length must be between 5 and 20.
			validation.Key("Name", validation.Required, validation.Length(5, 20)),
			// Email cannot be empty and should be in a valid email format.
			validation.Key("Email", validation.Required, is.Email),
			// Validate Address using its own validation rules
			validation.Key("Address", validation.Map(
				// Street cannot be empty, and the length must between 5 and 50
				validation.Key("Street", validation.Required, validation.Length(5, 50)),
				// City cannot be empty, and the length must between 5 and 50
				validation.Key("City", validation.Required, validation.Length(5, 50)),
				// State cannot be empty, and must be a string consisting of two letters in upper case
				validation.Key("State", validation.Required, validation.Match(regexp.MustCompile("^[A-Z]{2}$"))),
				// State cannot be empty, and must be a string consisting of five digits
				validation.Key("Zip", validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
			)),
		),
	)
	fmt.Println(err)
}

Output:

Address: (State: must be in a valid format; Street: the length must be between 5 and 50.); Email: must be a valid email address.
Example (Six) 
package main

import (
	"context"
	"errors"
	"fmt"

	"github.com/invopop/validation"
)

type contextKey int

func main() {
	key := contextKey(1)
	rule := validation.WithContext(func(ctx context.Context, value interface{}) error {
		s, _ := value.(string)
		if ctx.Value(key) == s {
			return nil
		}
		return errors.New("unexpected value")
	})
	ctx := context.WithValue(context.Background(), key, "good sample")

	err1 := validation.ValidateWithContext(ctx, "bad sample", rule)
	fmt.Println(err1)

	err2 := validation.ValidateWithContext(ctx, "good sample", rule)
	fmt.Println(err2)

}

Output:

unexpected value
<nil>
Example (Third) 
package main

import (
	"fmt"
	"regexp"

	"github.com/invopop/validation"
)

type Address struct {
	Street string
	City   string
	State  string
	Zip    string
}

func (a Address) Validate() error {
	return validation.ValidateStruct(&a,

		validation.Field(&a.Street, validation.Required, validation.Length(5, 50)),

		validation.Field(&a.City, validation.Required, validation.Length(5, 50)),

		validation.Field(&a.State, validation.Required, validation.Match(regexp.MustCompile("^[A-Z]{2}$"))),

		validation.Field(&a.Zip, validation.Required, validation.Match(regexp.MustCompile("^[0-9]{5}$"))),
	)
}

func main() {
	addresses := []Address{
		{State: "MD", Zip: "12345"},
		{Street: "123 Main St", City: "Vienna", State: "VA", Zip: "12345"},
		{City: "Unknown", State: "NC", Zip: "123"},
	}
	err := validation.Validate(addresses)
	fmt.Println(err)
}

Output:

0: (City: cannot be blank; Street: cannot be blank.); 2: (Street: cannot be blank; Zip: must be in a valid format.).

Index

Examples

Constants

This section is empty.

Variables

View Source 
var (
	// ErrNil is the error that returns when a value is not nil.
	ErrNil = NewError("validation_nil", "must be blank")
	// ErrEmpty is the error that returns when a not nil value is not empty.
	ErrEmpty = NewError("validation_empty", "must be blank")
)
View Source 
var (
	// ErrDateInvalid is the error that returns in case of an invalid date.
	ErrDateInvalid = NewError("validation_date_invalid", "must be a valid date")
	// ErrDateOutOfRange is the error that returns in case of an invalid date.
	ErrDateOutOfRange = NewError("validation_date_out_of_range", "the date is out of range")
)
View Source 
var (
	// ErrLengthTooLong is the error that returns in case of too long length.
	ErrLengthTooLong = NewError("validation_length_too_long", "the length must be no more than {{.max}}")
	// ErrLengthTooShort is the error that returns in case of too short length.
	ErrLengthTooShort = NewError("validation_length_too_short", "the length must be no less than {{.min}}")
	// ErrLengthInvalid is the error that returns in case of an invalid length.
	ErrLengthInvalid = NewError("validation_length_invalid", "the length must be exactly {{.min}}")
	// ErrLengthOutOfRange is the error that returns in case of out of range length.
	ErrLengthOutOfRange = NewError("validation_length_out_of_range", "the length must be between {{.min}} and {{.max}}")
	// ErrLengthEmptyRequired is the error that returns in case of non-empty value.
	ErrLengthEmptyRequired = NewError("validation_length_empty_required", "the value must be empty")
)
View Source 
var (
	// ErrNotMap is the error that the value being validated is not a map.
	ErrNotMap = errors.New("only a map can be validated")

	// ErrKeyWrongType is the error returned in case of an incorrect key type.
	ErrKeyWrongType = NewError("validation_key_wrong_type", "key not the correct type")

	// ErrKeyMissing is the error returned in case of a missing key.
	ErrKeyMissing = NewError("validation_key_missing", "required key is missing")

	// ErrKeyUnexpected is the error returned in case of an unexpected key.
	ErrKeyUnexpected = NewError("validation_key_unexpected", "key not expected")
)
View Source 
var (
	// ErrMinGreaterEqualThanRequired is the error that returns when a value is less than a specified threshold.
	ErrMinGreaterEqualThanRequired = NewError("validation_min_greater_equal_than_required", "must be no less than {{.threshold}}")
	// ErrMaxLessEqualThanRequired is the error that returns when a value is greater than a specified threshold.
	ErrMaxLessEqualThanRequired = NewError("validation_max_less_equal_than_required", "must be no greater than {{.threshold}}")
	// ErrMinGreaterThanRequired is the error that returns when a value is less than or equal to a specified threshold.
	ErrMinGreaterThanRequired = NewError("validation_min_greater_than_required", "must be greater than {{.threshold}}")
	// ErrMaxLessThanRequired is the error that returns when a value is greater than or equal to a specified threshold.
	ErrMaxLessThanRequired = NewError("validation_max_less_than_required", "must be less than {{.threshold}}")
)
View Source 
var (
	// ErrRequired is the error that returns when a value is required.
	ErrRequired = NewError("validation_required", "cannot be blank")
	// ErrNilOrNotEmpty is the error that returns when a value is not nil and is empty.
	ErrNilOrNotEmpty = NewError("validation_nil_or_not_empty_required", "cannot be blank")
)
View Source 
var (
	// ErrorTag is the struct tag name used to customize the error field name for a struct field.
	ErrorTag = "json"

	// Skip is a special validation rule that indicates all rules following it should be skipped.
	Skip = skipRule{/* contains filtered or unexported fields */}
)
View Source 
var Empty = absentRule{/* contains filtered or unexported fields */}

Empty checks if a not nil value is empty.

View Source 
var ErrInInvalid = NewError("validation_in_invalid", "must be a valid value")

ErrInInvalid is the error that returns in case of an invalid value for "in" rule.

View Source 
var ErrMatchInvalid = NewError("validation_match_invalid", "must be in a valid format")

ErrMatchInvalid is the error that returns in case of invalid format.

View Source 
var ErrMultipleOfInvalid = NewError("validation_multiple_of_invalid", "must be multiple of {{.base}}")

ErrMultipleOfInvalid is the error that returns when a value is not multiple of a base.

View Source 
var ErrNotInInvalid = NewError("validation_not_in_invalid", "must not be in list")

ErrNotInInvalid is the error that returns when a value is in a list.

View Source 
var ErrNotNilRequired = NewError("validation_not_nil_required", "is required")

ErrNotNilRequired is the error that returns when a value is Nil.

View Source 
var (
	// ErrStructPointer is the error that a struct being validated is not specified as a pointer.
	ErrStructPointer = errors.New("only a pointer to a struct can be validated")
)
View Source 
var Nil = absentRule{/* contains filtered or unexported fields */}

Nil is a validation rule that checks if a value is nil. It is the opposite of NotNil rule

View Source 
var NilOrNotEmpty = RequiredRule{/* contains filtered or unexported fields */}

NilOrNotEmpty checks if a value is a nil pointer or a value that is not empty. NilOrNotEmpty differs from Required in that it treats a nil pointer as valid.

View Source 
var NotNil = notNilRule{}

NotNil is a validation rule that checks if a value is not nil. NotNil only handles types including interface, pointer, slice, and map. All other types are considered valid.

View Source 
var Required = RequiredRule{/* contains filtered or unexported fields */}

Required is a validation rule that checks if a value is not empty. A value is considered not empty if - integer, float: not zero - bool: true - string, array, slice, map: len() > 0 - interface, pointer: not nil and the referenced value is not empty - any other types

Functions

func EnsureString 

func EnsureString(value interface{}) (string, error)

EnsureString ensures the given value is a string. If the value is a byte slice, it will be typecast into a string. An error is returned otherwise.

func Indirect 

func Indirect(value interface{}) (interface{}, bool)

Indirect returns the value that the given interface or pointer references to. If the value implements driver.Valuer, it will deal with the value returned by the Value() method instead. A boolean value is also returned to indicate if the value is nil or not (only applicable to interface, pointer, map, and slice). If the value is neither an interface nor a pointer, it will be returned back.

func IsEmpty 

func IsEmpty(value interface{}) bool

IsEmpty checks if a value is empty or not. A value is considered empty if - integer, float: zero - bool: false - string, array: len() == 0 - slice, map: nil or len() == 0 - interface, pointer: nil or the referenced value is empty

func LengthOfValue 

func LengthOfValue(value interface{}) (int, error)

LengthOfValue returns the length of a value that is a string, slice, map, or array. An error is returned for all other types.

func StringOrBytes 

func StringOrBytes(value interface{}) (isString bool, str string, isBytes bool, bs []byte)

StringOrBytes typecasts a value into a string or byte slice. Boolean flags are returned to indicate if the typecasting succeeds or not.

func ToFloat 

func ToFloat(value interface{}) (float64, error)

ToFloat converts the given value to a float64. An error is returned for all incompatible types.

func ToInt 

func ToInt(value interface{}) (int64, error)

ToInt converts the given value to an int64. An error is returned for all incompatible types.

func ToUint 

func ToUint(value interface{}) (uint64, error)

ToUint converts the given value to an uint64. An error is returned for all incompatible types.

func Validate 

func Validate(value interface{}, rules ...Rule) error

Validate validates the given value and returns the validation error, if any.

Validate performs validation using the following steps:

  1. For each rule, call its `Validate()` to validate the value. Return if any error is found.
  2. If the value being validated implements `Validatable`, call the value's `Validate()`. Return with the validation result.
  3. If the value being validated is a map/slice/array, and the element type implements `Validatable`, for each element call the element value's `Validate()`. Return with the validation result.

func ValidateStruct 

func ValidateStruct(structPtr interface{}, fields ...*FieldRules) error

ValidateStruct validates a struct by checking the specified struct fields against the corresponding validation rules. Note that the struct being validated must be specified as a pointer to it. If the pointer is nil, it is considered valid. Use Field() to specify struct fields that need to be validated. Each Field() call specifies a single field which should be specified as a pointer to the field. A field can be associated with multiple rules. For example, 

value := struct {
    Name  string
    Value string
}{"name", "demo"}
err := validation.ValidateStruct(&value,
    validation.Field(&a.Name, validation.Required),
    validation.Field(&a.Value, validation.Required, validation.Length(5, 10)),
)
fmt.Println(err)
// Value: the length must be between 5 and 10.

An error will be returned if validation fails.

func ValidateStructWithContext 

func ValidateStructWithContext(ctx context.Context, structPtr interface{}, fields ...*FieldRules) error

ValidateStructWithContext validates a struct with the given context. The only difference between ValidateStructWithContext and ValidateStruct is that the former will validate struct fields with the provided context. Please refer to ValidateStruct for the detailed instructions on how to use this function.

func ValidateWithContext 

func ValidateWithContext(ctx context.Context, value interface{}, rules ...Rule) error

ValidateWithContext validates the given value with the given context and returns the validation error, if any.

ValidateWithContext performs validation using the following steps:

  1. For each rule, call its `ValidateWithContext()` to validate the value if the rule implements `RuleWithContext`. Otherwise call `Validate()` of the rule. Return if any error is found.
  2. If the value being validated implements `ValidatableWithContext`, call the value's `ValidateWithContext()` and return with the validation result.
  3. If the value being validated implements `Validatable`, call the value's `Validate()` and return with the validation result.
  4. If the value being validated is a map/slice/array, and the element type implements `ValidatableWithContext`, for each element call the element value's `ValidateWithContext()`. Return with the validation result.
  5. If the value being validated is a map/slice/array, and the element type implements `Validatable`, for each element call the element value's `Validate()`. Return with the validation result.

Types

type DateRule 

type DateRule struct {
	// contains filtered or unexported fields
}

DateRule is a validation rule that validates date/time string values.

func Date 

func Date(layout string) DateRule

Date returns a validation rule that checks if a string value is in a format that can be parsed into a date. The format of the date should be specified as the layout parameter which accepts the same value as that for time.Parse. For example, 

validation.Date(time.ANSIC)
validation.Date("02 Jan 06 15:04 MST")
validation.Date("2006-01-02")

By calling Min() and/or Max(), you can let the Date rule to check if a parsed date value is within the specified date range.

An empty value is considered valid. Use the Required rule to make sure a value is not empty.

func (DateRule) Error 

func (r DateRule) Error(message string) DateRule

Error sets the error message that is used when the value being validated is not a valid date.

func (DateRule) ErrorObject 

func (r DateRule) ErrorObject(err Error) DateRule

ErrorObject sets the error struct that is used when the value being validated is not a valid date..

func (DateRule) Max 

func (r DateRule) Max(max time.Time) DateRule

Max sets the maximum date range. A zero value means skipping the maximum range validation.

func (DateRule) Min 

func (r DateRule) Min(min time.Time) DateRule

Min sets the minimum date range. A zero value means skipping the minimum range validation.

func (DateRule) RangeError 

func (r DateRule) RangeError(message string) DateRule

RangeError sets the error message that is used when the value being validated is out of the specified Min/Max date range.

func (DateRule) RangeErrorObject 

func (r DateRule) RangeErrorObject(err Error) DateRule

RangeErrorObject sets the error struct that is used when the value being validated is out of the specified Min/Max date range.

func (DateRule) Validate 

func (r DateRule) Validate(value interface{}) error

Validate checks if the given value is a valid date.

type EachRule 

type EachRule struct {
	// contains filtered or unexported fields
}

EachRule is a validation rule that validates elements in a map/slice/array using the specified list of rules.

func Each 

func Each(rules ...Rule) EachRule

Each returns a validation rule that loops through an iterable (map, slice or array) and validates each value inside with the provided rules. An empty iterable is considered valid. Use the Required rule to make sure the iterable is not empty.

func (EachRule) Validate 

func (r EachRule) Validate(value interface{}) error

Validate loops through the given iterable and calls the Ozzo Validate() method for each value.

func (EachRule) ValidateWithContext 

func (r EachRule) ValidateWithContext(ctx context.Context, value interface{}) error

ValidateWithContext loops through the given iterable and calls the Ozzo ValidateWithContext() method for each value.

type ErrFieldNotFound 

type ErrFieldNotFound int

ErrFieldNotFound is the error that a field cannot be found in the struct.

func (ErrFieldNotFound) Error 

func (e ErrFieldNotFound) Error() string

Error returns the error string of ErrFieldNotFound.

type ErrFieldPointer 

type ErrFieldPointer int

ErrFieldPointer is the error that a field is not specified as a pointer.

func (ErrFieldPointer) Error 

func (e ErrFieldPointer) Error() string

Error returns the error string of ErrFieldPointer.

type Error 

type Error interface {
	Error() string
	Code() string
	Message() string
	SetMessage(string) Error
	Params() map[string]interface{}
	SetParams(map[string]interface{}) Error
}

Error interface represents an validation error

func NewError 

func NewError(code, message string) Error

NewError create new validation error.

type ErrorObject 

type ErrorObject struct {
	// contains filtered or unexported fields
}

ErrorObject is the default validation error that implements the Error interface.

func (ErrorObject) AddParam 

func (e ErrorObject) AddParam(name string, value interface{}) Error

AddParam add parameter to the error's parameters.

func (ErrorObject) Code 

func (e ErrorObject) Code() string

Code get the error's translation code.

func (ErrorObject) Error 

func (e ErrorObject) Error() string

Error returns the error message.

func (ErrorObject) Message 

func (e ErrorObject) Message() string

Message return the error's message.

func (ErrorObject) Params 

func (e ErrorObject) Params() map[string]interface{}

Params returns the error's params.

func (ErrorObject) SetCode 

func (e ErrorObject) SetCode(code string) Error

SetCode set the error's translation code.

func (ErrorObject) SetMessage 

func (e ErrorObject) SetMessage(message string) Error

SetMessage set the error's message.

func (ErrorObject) SetParams 

func (e ErrorObject) SetParams(params map[string]interface{}) Error

SetParams set the error's params.

type Errors 

type Errors map[string]error

Errors represents the validation errors that are indexed by struct field names, map or slice keys. values are Error or Errors (for map, slice and array error value is Errors).

func (Errors) Error 

func (es Errors) Error() string

Error returns the error string of Errors.

func (Errors) Filter 

func (es Errors) Filter() error

Filter removes all nils from Errors and returns back the updated Errors as an error. If the length of Errors becomes 0, it will return nil.

func (Errors) MarshalJSON 

func (es Errors) MarshalJSON() ([]byte, error)

MarshalJSON converts the Errors into a valid JSON.

type FieldRules 

type FieldRules struct {
	// contains filtered or unexported fields
}

FieldRules represents a rule set associated with a struct field.

func Field 

func Field(fieldPtr interface{}, rules ...Rule) *FieldRules

Field specifies a struct field and the corresponding validation rules. The struct field must be specified as a pointer to it.

type InRule 

type InRule[T any] struct {
	// contains filtered or unexported fields
}

InRule is a validation rule that validates if a value can be found in the given list of values.

func In 

func In[T any](values ...T) InRule[T]

In returns a validation rule that checks if a value can be found in the given list of values. reflect.DeepEqual() will be used to determine if two values are equal. For more details please refer to https://golang.org/pkg/reflect/#DeepEqual An empty value is considered valid. Use the Required rule to make sure a value is not empty.

func (InRule[T]) Error 

func (r InRule[T]) Error(message string) InRule[T]

Error sets the error message for the rule.

func (InRule[T]) ErrorObject 

func (r InRule[T]) ErrorObject(err Error) InRule[T]

ErrorObject sets the error struct for the rule.

func (InRule[T]) Validate 

func (r InRule[T]) Validate(value interface{}) error

Validate checks if the given value is valid or not.

type InternalError 

type InternalError interface {
	error
	InternalError() error
}

InternalError represents an error that should NOT be treated as a validation error.

func NewInternalError 

func NewInternalError(err error) InternalError

NewInternalError wraps a given error into an InternalError.

type KeyRules 

type KeyRules struct {
	// contains filtered or unexported fields
}

KeyRules represents a rule set associated with a map key.

func Key 

func Key(key interface{}, rules ...Rule) *KeyRules

Key specifies a map key and the corresponding validation rules.

func (*KeyRules) Optional 

func (r *KeyRules) Optional() *KeyRules

Optional configures the rule to ignore the key if missing.

type LengthRule 

type LengthRule struct {
	// contains filtered or unexported fields
}

LengthRule is a validation rule that checks if a value's length is within the specified range.

func Length 

func Length(min, max int) LengthRule

Length returns a validation rule that checks if a value's length is within the specified range. If max is 0, it means there is no upper bound for the length. This rule should only be used for validating strings, slices, maps, and arrays. An empty value is considered valid. Use the Required rule to make sure a value is not empty.

func RuneLength 

func RuneLength(min, max int) LengthRule

RuneLength returns a validation rule that checks if a string's rune length is within the specified range. If max is 0, it means there is no upper bound for the length. This rule should only be used for validating strings, slices, maps, and arrays. An empty value is considered valid. Use the Required rule to make sure a value is not empty. If the value being validated is not a string, the rule works the same as Length.

func (LengthRule) Error 

func (r LengthRule) Error(message string) LengthRule

Error sets the error message for the rule.

func (LengthRule) ErrorObject 

func (r LengthRule) ErrorObject(err Error) LengthRule

ErrorObject sets the error struct for the rule.

func (LengthRule) Validate 

func (r LengthRule) Validate(value interface{}) error

Validate checks if the given value is valid or not.

type MapRule 

type MapRule struct {
	// contains filtered or unexported fields
}

MapRule represents a rule set associated with a map.

func Map 

func Map(keys ...*KeyRules) MapRule

Map returns a validation rule that checks the keys and values of a map. This rule should only be used for validating maps, or a validation error will be reported. Use Key() to specify map keys that need to be validated. Each Key() call specifies a single key which can be associated with multiple rules. For example, 

validation.Map(
    validation.Key("Name", validation.Required),
    validation.Key("Value", validation.Required, validation.Length(5, 10)),
)

A nil value is considered valid. Use the Required rule to make sure a map value is present.

func (MapRule) AllowExtraKeys 

func (r MapRule) AllowExtraKeys() MapRule

AllowExtraKeys configures the rule to ignore extra keys.

func (MapRule) Validate 

func (r MapRule) Validate(m interface{}) error

Validate checks if the given value is valid or not.

func (MapRule) ValidateWithContext 

func (r MapRule) ValidateWithContext(ctx context.Context, m interface{}) error

ValidateWithContext checks if the given value is valid or not.

type MatchRule 

type MatchRule struct {
	// contains filtered or unexported fields
}

MatchRule is a validation rule that checks if a value matches the specified regular expression.

func Match 

func Match(re *regexp.Regexp) MatchRule

Match returns a validation rule that checks if a value matches the specified regular expression. This rule should only be used for validating strings and byte slices, or a validation error will be reported. An empty value is considered valid. Use the Required rule to make sure a value is not empty.

func (MatchRule) Error 

func (r MatchRule) Error(message string) MatchRule

Error sets the error message for the rule.

func (MatchRule) ErrorObject 

func (r MatchRule) ErrorObject(err Error) MatchRule

ErrorObject sets the error struct for the rule.

func (MatchRule) Validate 

func (r MatchRule) Validate(value interface{}) error

Validate checks if the given value is valid or not.

type MultipleOfRule 

type MultipleOfRule struct {
	// contains filtered or unexported fields
}

MultipleOfRule is a validation rule that checks if a value is a multiple of the "base" value.

func MultipleOf 

func MultipleOf(base interface{}) MultipleOfRule

MultipleOf returns a validation rule that checks if a value is a multiple of the "base" value. Note that "base" should be of integer type.

func (MultipleOfRule) Error 

func (r MultipleOfRule) Error(message string) MultipleOfRule

Error sets the error message for the rule.

func (MultipleOfRule) ErrorObject 

func (r MultipleOfRule) ErrorObject(err Error) MultipleOfRule

ErrorObject sets the error struct for the rule.

func (MultipleOfRule) Validate 

func (r MultipleOfRule) Validate(value interface{}) error

Validate checks if the value is a multiple of the "base" value.

type NotInRule 

type NotInRule[T any] struct {
	// contains filtered or unexported fields
}

NotInRule is a validation rule that checks if a value is absent from the given list of values.

func NotIn 

func NotIn[T any](values ...T) NotInRule[T]

NotIn returns a validation rule that checks if a value is absent from the given list of values. Like with In(), reflect.DeepEqual() will be used to determine if two values are equal. An empty value is considered valid. Use the Required rule to make sure a value is not empty.

func (NotInRule[T]) Error 

func (r NotInRule[T]) Error(message string) NotInRule[T]

Error sets the error message for the rule.

func (NotInRule[T]) ErrorObject 

func (r NotInRule[T]) ErrorObject(err Error) NotInRule[T]

ErrorObject sets the error struct for the rule.

func (NotInRule[T]) Validate 

func (r NotInRule[T]) Validate(value interface{}) error

Validate checks if the given value is valid or not.

type RequiredRule 

type RequiredRule struct {
	// contains filtered or unexported fields
}

RequiredRule is a rule that checks if a value is not empty.

func (RequiredRule) Error 

func (r RequiredRule) Error(message string) RequiredRule

Error sets the error message for the rule.

func (RequiredRule) ErrorObject 

func (r RequiredRule) ErrorObject(err Error) RequiredRule

ErrorObject sets the error struct for the rule.

func (RequiredRule) Validate 

func (r RequiredRule) Validate(value interface{}) error

Validate checks if the given value is valid or not.

func (RequiredRule) When 

func (r RequiredRule) When(condition bool) RequiredRule

When sets the condition that determines if the validation should be performed.

type Rule 

type Rule interface {
	// Validate validates a value and returns a value if validation fails.
	Validate(value interface{}) error
}

Rule represents a validation rule.

func By 

func By(f RuleFunc) Rule

By wraps a RuleFunc into a Rule.

func WithContext 

func WithContext(f RuleWithContextFunc) Rule

WithContext wraps a RuleWithContextFunc into a context-aware Rule.

type RuleFunc 

type RuleFunc func(value interface{}) error

RuleFunc represents a validator function. You may wrap it as a Rule by calling By().

type RuleWithContext 

type RuleWithContext interface {
	// ValidateWithContext validates a value and returns a value if validation fails.
	ValidateWithContext(ctx context.Context, value interface{}) error
}

RuleWithContext represents a context-aware validation rule.

type RuleWithContextFunc 

type RuleWithContextFunc func(ctx context.Context, value interface{}) error

RuleWithContextFunc represents a validator function that is context-aware. You may wrap it as a Rule by calling WithContext().

type StringRule 

type StringRule struct {
	// contains filtered or unexported fields
}

StringRule is a rule that checks a string variable using a specified stringValidator.

func NewStringRule 

func NewStringRule(validator stringValidator, message string) StringRule

NewStringRule creates a new validation rule using a function that takes a string value and returns a bool. The rule returned will use the function to check if a given string or byte slice is valid or not. An empty value is considered to be valid. Please use the Required rule to make sure a value is not empty.

func NewStringRuleWithError 

func NewStringRuleWithError(validator stringValidator, err Error) StringRule

NewStringRuleWithError creates a new validation rule using a function that takes a string value and returns a bool. The rule returned will use the function to check if a given string or byte slice is valid or not. An empty value is considered to be valid. Please use the Required rule to make sure a value is not empty.

func (StringRule) Error 

func (r StringRule) Error(message string) StringRule

Error sets the error message for the rule.

func (StringRule) ErrorObject 

func (r StringRule) ErrorObject(err Error) StringRule

ErrorObject sets the error struct for the rule.

func (StringRule) Validate 

func (r StringRule) Validate(value interface{}) error

Validate checks if the given value is valid or not.

type ThresholdRule 

type ThresholdRule struct {
	// contains filtered or unexported fields
}

ThresholdRule is a validation rule that checks if a value satisfies the specified threshold requirement.

func Max 

func Max(max interface{}) ThresholdRule

Max returns a validation rule that checks if a value is less or equal than the specified value. By calling Exclusive, the rule will check if the value is strictly less than the specified value. Note that the value being checked and the threshold value must be of the same type. Only int, uint, float and time.Time types are supported. An empty value is considered valid. Please use the Required rule to make sure a value is not empty.

func Min 

func Min(min interface{}) ThresholdRule

Min returns a validation rule that checks if a value is greater or equal than the specified value. By calling Exclusive, the rule will check if the value is strictly greater than the specified value. Note that the value being checked and the threshold value must be of the same type. Only int, uint, float and time.Time types are supported. An empty value is considered valid. Please use the Required rule to make sure a value is not empty.

func (ThresholdRule) Error 

func (r ThresholdRule) Error(message string) ThresholdRule

Error sets the error message for the rule.

func (ThresholdRule) ErrorObject 

func (r ThresholdRule) ErrorObject(err Error) ThresholdRule

ErrorObject sets the error struct for the rule.

func (ThresholdRule) Exclusive 

func (r ThresholdRule) Exclusive() ThresholdRule

Exclusive sets the comparison to exclude the boundary value.

func (ThresholdRule) Validate 

func (r ThresholdRule) Validate(value interface{}) error

Validate checks if the given value is valid or not.

type Validatable 

type Validatable interface {
	// Validate validates the data and returns an error if validation fails.
	Validate() error
}

Validatable is the interface indicating the type implementing it supports data validation.

type ValidatableWithContext 

type ValidatableWithContext interface {
	// ValidateWithContext validates the data with the given context and returns an error if validation fails.
	ValidateWithContext(ctx context.Context) error
}

ValidatableWithContext is the interface indicating the type implementing it supports context-aware data validation.

type WhenRule 

type WhenRule struct {
	// contains filtered or unexported fields
}

WhenRule is a validation rule that executes the given list of rules when the condition is true.

func When 

func When(condition bool, rules ...Rule) WhenRule

When returns a validation rule that executes the given list of rules when the condition is true.

func (WhenRule) Else 

func (r WhenRule) Else(rules ...Rule) WhenRule

Else returns a validation rule that executes the given list of rules when the condition is false.

func (WhenRule) Validate 

func (r WhenRule) Validate(value interface{}) error

Validate checks if the condition is true and if so, it validates the value using the specified rules.

func (WhenRule) ValidateWithContext 

func (r WhenRule) ValidateWithContext(ctx context.Context, value interface{}) error

ValidateWithContext checks if the condition is true and if so, it validates the value using the specified rules.

Source Files

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Directories

Path Synopsis
Package is provides a list of commonly used string validation rules.
 Package is provides a list of commonly used string validation rules.

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