Documentation ¶
Overview ¶
Package form Decodes url.Values into Go value(s) and Encodes Go value(s) into url.Values.
It has the following features:
- Primitives types cause zero allocations.
- Supports map of almost all types.
- Supports both Numbered and Normal arrays eg. "Array[0]" and just "Array" with multiple values passed.
- Slice honours the specified index. eg. if "Slice[2]" is the only Slice value passed down, it will be put at index 2; if slice isn't big enough it will be expanded.
- Array honours the specified index. eg. if "Array[2]" is the only Array value passed down, it will be put at index 2; if array isn't big enough a warning will be printed and value ignored.
- Only creates objects as necessary eg. if no `array` or `map` values are passed down, the `array` and `map` are left as their default values in the struct.
- Allows for Custom Type registration.
- Handles time.Time using RFC3339 time format by default, but can easily be changed by registering a Custom Type, see below.
- Handles Encoding & Decoding of almost all Go types eg. can Decode into struct, array, map, int... and Encode a struct, array, map, int...
Common Questions ¶
Questions
Does it support encoding.TextUnmarshaler? No because TextUnmarshaler only accepts []byte but posted values can have multiple values, so is not suitable. Mixing array/slice with array[idx]/slice[idx], in which order are they parsed? array/slice then array[idx]/slice[idx]
Supported Types ¶
out of the box supported types
string
bool
int, int8, int16, int32, int64
uint, uint8, uint16, uint32, uint64
float32, float64
struct and anonymous struct
interface{}
time.Time` - by default using RFC3339
a `pointer` to one of the above types
slice, array
map
`custom types` can override any of the above types
many other types may be supported inherently (eg. bson.ObjectId is type ObjectId string, which will get populated by the string type
**NOTE**: map, struct and slice nesting are ad infinitum.
Usage ¶
symbols
- Use symbol `.` for separating fields/structs. (eg. `structfield.field`)
- Use `[index or key]` for access to index of a slice/array or key for map. (eg. `arrayfield[0]`, `mapfield[keyvalue]`)
html
<form method="POST"> <input type="text" name="Name" value="joeybloggs"/> <input type="text" name="Age" value="3"/> <input type="text" name="Gender" value="Male"/> <input type="text" name="Address[0].Name" value="26 Here Blvd."/> <input type="text" name="Address[0].Phone" value="9(999)999-9999"/> <input type="text" name="Address[1].Name" value="26 There Blvd."/> <input type="text" name="Address[1].Phone" value="1(111)111-1111"/> <input type="text" name="active" value="true"/> <input type="text" name="MapExample[key]" value="value"/> <input type="text" name="NestedMap[key][key]" value="value"/> <input type="text" name="NestedArray[0][0]" value="value"/> <input type="submit"/> </form>
Example ¶
example decoding the above HTML
package main import ( "fmt" "log" "net/url" "github.com/go-playground/form" ) // Address contains address information type Address struct { Name string Phone string } // User contains user information type User struct { Name string Age uint8 Gender string Address []Address Active bool `form:"active"` MapExample map[string]string NestedMap map[string]map[string]string NestedArray [][]string } // use a single instance of Decoder, it caches struct info var decoder *form.Decoder func main() { decoder = form.NewDecoder() // this simulates the results of http.Request's ParseForm() function values := parseForm() var user User // must pass a pointer err := decoder.Decode(&user, values) if err != nil { log.Panic(err) } fmt.Printf("%#v\n", user) } // this simulates the results of http.Request's ParseForm() function func parseForm() url.Values { return url.Values{ "Name": []string{"joeybloggs"}, "Age": []string{"3"}, "Gender": []string{"Male"}, "Address[0].Name": []string{"26 Here Blvd."}, "Address[0].Phone": []string{"9(999)999-9999"}, "Address[1].Name": []string{"26 There Blvd."}, "Address[1].Phone": []string{"1(111)111-1111"}, "active": []string{"true"}, "MapExample[key]": []string{"value"}, "NestedMap[key][key]": []string{"value"}, "NestedArray[0][0]": []string{"value"}, } }
example encoding
package main import ( "fmt" "log" "github.com/go-playground/form" ) // Address contains address information type Address struct { Name string Phone string } // User contains user information type User struct { Name string Age uint8 Gender string Address []Address Active bool `form:"active"` MapExample map[string]string NestedMap map[string]map[string]string NestedArray [][]string } // use a single instance of Encoder, it caches struct info var encoder *form.Encoder func main() { encoder = form.NewEncoder() user := User{ Name: "joeybloggs", Age: 3, Gender: "Male", Address: []Address{ {Name: "26 Here Blvd.", Phone: "9(999)999-9999"}, {Name: "26 There Blvd.", Phone: "1(111)111-1111"}, }, Active: true, MapExample: map[string]string{"key": "value"}, NestedMap: map[string]map[string]string{"key": {"key": "value"}}, NestedArray: [][]string{{"value"}}, } // must pass a pointer values, err := encoder.Encode(&user) if err != nil { log.Panic(err) } fmt.Printf("%#v\n", values) }
Registering Custom Types ¶
Decoder
decoder.RegisterCustomTypeFunc(func(vals []string) (interface{}, error) { return time.Parse("2006-01-02", vals[0]) }, time.Time{}) ADDITIONAL: if a struct type is registered, the function will only be called if a url.Value exists for the struct and not just the struct fields eg. url.Values{"User":"Name%3Djoeybloggs"} will call the custom type function with 'User' as the type, however url.Values{"User.Name":"joeybloggs"} will not.
Encoder
encoder.RegisterCustomTypeFunc(func(x interface{}) ([]string, error) { return []string{x.(time.Time).Format("2006-01-02")}, nil }, time.Time{})
Ignoring Fields ¶
you can tell form to ignore fields using `-` in the tag
type MyStruct struct { Field string `form:"-"` }
Omitempty ¶
you can tell form to omit empty fields using `,omitempty` or `FieldName,omitempty` in the tag
type MyStruct struct { Field string `form:",omitempty"` Field2 string `form:"CustomFieldName,omitempty"` }
Notes ¶
To maximize compatibility with other systems the Encoder attempts to avoid using array indexes in url.Values if at all possible.
eg. // A struct field of Field []string{"1", "2", "3"} // will be output a url.Value as "Field": []string{"1", "2", "3"} and not "Field[0]": []string{"1"} "Field[1]": []string{"2"} "Field[2]": []string{"3"} // however there are times where it is unavoidable, like with pointers i := int(1) Field []*string{nil, nil, &i} // to avoid index 1 and 2 must use index "Field[2]": []string{"1"}
Index ¶
- func ExtractType(current reflect.Value) (reflect.Value, reflect.Kind)
- type AnonymousMode
- type DecodeCustomTypeFunc
- type DecodeErrors
- type Decoder
- func (d *Decoder) Decode(v interface{}, values url.Values) (err error)
- func (d *Decoder) RegisterCustomTypeFunc(fn DecodeCustomTypeFunc, types ...interface{})
- func (d *Decoder) RegisterTagNameFunc(fn TagNameFunc)
- func (d *Decoder) SetMaxArraySize(size uint)
- func (d *Decoder) SetMode(mode Mode)
- func (d *Decoder) SetTagName(tagName string)
- type EncodeCustomTypeFunc
- type EncodeErrors
- type Encoder
- func (e *Encoder) Encode(v interface{}) (values url.Values, err error)
- func (e *Encoder) RegisterCustomTypeFunc(fn EncodeCustomTypeFunc, types ...interface{})
- func (e *Encoder) RegisterTagNameFunc(fn TagNameFunc)
- func (e *Encoder) SetAnonymousMode(mode AnonymousMode)
- func (e *Encoder) SetMode(mode Mode)
- func (e *Encoder) SetTagName(tagName string)
- type InvalidDecoderError
- type InvalidEncodeError
- type Mode
- type TagNameFunc
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type AnonymousMode ¶
type AnonymousMode uint8
AnonymousMode specifies how data should be rolled up or separated from anonymous structs
const ( // AnonymousEmbed embeds anonymous data when encoding // eg. type A struct { Field string } // type B struct { A, Field string } // encode results: url.Values{"Field":[]string{"B FieldVal", "A FieldVal"}} AnonymousEmbed AnonymousMode = iota // AnonymousSeparate does not embed anonymous data when encoding // eg. type A struct { Field string } // type B struct { A, Field string } // encode results: url.Values{"Field":[]string{"B FieldVal"}, "A.Field":[]string{"A FieldVal"}} AnonymousSeparate )
type DecodeCustomTypeFunc ¶ added in v1.3.0
DecodeCustomTypeFunc allows for registering/overriding types to be parsed.
type DecodeErrors ¶
DecodeErrors is a map of errors encountered during form decoding
func (DecodeErrors) Error ¶
func (d DecodeErrors) Error() string
type Decoder ¶
type Decoder struct {
// contains filtered or unexported fields
}
Decoder is the main decode instance
func NewDecoder ¶
func NewDecoder() *Decoder
NewDecoder creates a new decoder instance with sane defaults
func (*Decoder) Decode ¶
Decode parses the given values and sets the corresponding struct and/or type values
Decode returns an InvalidDecoderError if interface passed is invalid.
func (*Decoder) RegisterCustomTypeFunc ¶
func (d *Decoder) RegisterCustomTypeFunc(fn DecodeCustomTypeFunc, types ...interface{})
RegisterCustomTypeFunc registers a CustomTypeFunc against a number of types. NOTE: This method is not thread-safe it is intended that these all be registered prior to any parsing
ADDITIONAL: if a struct type is registered, the function will only be called if a url.Value exists for the struct and not just the struct fields eg. url.Values{"User":"Name%3Djoeybloggs"} will call the custom type function with `User` as the type, however url.Values{"User.Name":"joeybloggs"} will not.
func (*Decoder) RegisterTagNameFunc ¶
func (d *Decoder) RegisterTagNameFunc(fn TagNameFunc)
RegisterTagNameFunc registers a custom tag name parser function NOTE: This method is not thread-safe it is intended that these all be registered prior to any parsing
ADDITIONAL: once a custom function has been registered the default, or custom set, tag name is ignored and relies 100% on the function for the name data. The return value WILL BE CACHED and so return value must be consistent.
func (*Decoder) SetMaxArraySize ¶ added in v1.5.0
SetMaxArraySize sets maximum array size that can be created. This limit is for the array indexing this library supports to avoid potential DOS or man-in-the-middle attacks using an unusually high number. DEFAULT: 10000
func (*Decoder) SetTagName ¶
SetTagName sets the given tag name to be used by the decoder. Default is "form"
type EncodeCustomTypeFunc ¶ added in v1.4.0
EncodeCustomTypeFunc allows for registering/overriding types to be parsed.
type EncodeErrors ¶ added in v1.4.0
EncodeErrors is a map of errors encountered during form encoding
func (EncodeErrors) Error ¶ added in v1.4.0
func (e EncodeErrors) Error() string
type Encoder ¶ added in v1.4.0
type Encoder struct {
// contains filtered or unexported fields
}
Encoder is the main encode instance
func NewEncoder ¶ added in v1.4.0
func NewEncoder() *Encoder
NewEncoder creates a new encoder instance with sane defaults
func (*Encoder) Encode ¶ added in v1.4.0
Encode encodes the given values and sets the corresponding struct values
func (*Encoder) RegisterCustomTypeFunc ¶ added in v1.4.0
func (e *Encoder) RegisterCustomTypeFunc(fn EncodeCustomTypeFunc, types ...interface{})
RegisterCustomTypeFunc registers a CustomTypeFunc against a number of types NOTE: this method is not thread-safe it is intended that these all be registered prior to any parsing
func (*Encoder) RegisterTagNameFunc ¶
func (e *Encoder) RegisterTagNameFunc(fn TagNameFunc)
RegisterTagNameFunc registers a custom tag name parser function NOTE: This method is not thread-safe it is intended that these all be registered prior to any parsing
ADDITIONAL: once a custom function has been registered the default, or custom set, tag name is ignored and relies 100% on the function for the name data. The return value WILL BE CACHED and so return value must be consistent.
func (*Encoder) SetAnonymousMode ¶
func (e *Encoder) SetAnonymousMode(mode AnonymousMode)
SetAnonymousMode sets the mode the encoder should run Default is AnonymousEmbed
func (*Encoder) SetTagName ¶ added in v1.4.0
SetTagName sets the given tag name to be used by the encoder. Default is "form"
type InvalidDecoderError ¶
An InvalidDecoderError describes an invalid argument passed to Decode. (The argument passed to Decode must be a non-nil pointer.)
func (*InvalidDecoderError) Error ¶
func (e *InvalidDecoderError) Error() string
type InvalidEncodeError ¶
An InvalidEncodeError describes an invalid argument passed to Encode.
func (*InvalidEncodeError) Error ¶
func (e *InvalidEncodeError) Error() string
type TagNameFunc ¶
type TagNameFunc func(field reflect.StructField) string
TagNameFunc allows for adding of a custom tag name parser