stagparser

README

stagparser - generic parser for golang struct tag

Package stagparser provides a generic parser for golang struct tag. stagparser can parse tags like the following:

• validate:"required,length(min=1, max=10)"
• validate:"max=10,list=[apple,'star fruits']"

tags consist of 'definition'. 'definition' has 3 forms:

• name only: required
• name with a single attribute: max=10
  • in this case, parse result is name="max", attributes={"max":10}
• name with multiple attributes: length(min=1, max=10)

name and attribute must be a golang identifier. An attribute value must be one of an int64, a float64, an identifier, a string quoted by ' and an array.

• int64: 123
• float64: 111.12
• string: 'ab\tc'
  • identifiers are interpreted as string in value context
• array: [1, 2, aaa]

You can parse objects just calling ParseStruct:

import "github.com/yuin/stagparser"

type User struct {
  Name string `validate:"required,length(min=4,max=10)"`
}

func main() {
  user := &User{"bob"}
  definitions, err := stagparser.ParseStruct(user)
}

License

MIT

Author

Yusuke Inuzuka

Documentation

Overview

Package stagparser provides a generic parser for golang struct tag. stagparser can parse tags like the following:

• `validate:"required,length(min=1, max=10)"`
• `validate:"max=10,list=[apple,'star fruits']"`

tags are consists of 'definition'. 'definition' have 3 forms:

• name only: required
• name with a single attribute: max=10
• in this case, parse result is name="max", attributes={"max":10}
• name with multiple attributes: length(min=1, max=10)

name and attribute must be a golang identifier. An attribute value must be one of an int64, a float64, an identifier, a string quoted by "'" and an array.

• int64: 123
• float64: 111.12
• string: 'ab\tc'
• identifiers are interpreted as string in value context
• array: [1, 2, aaa]

You can parse objects just call ParseStruct:

import "github.com/yuin/stagparser"

type User struct {
  Name string `validate:"required,length(min=4,max=10)"`
}

func main() {
  user := &User{"bob"}
  definitions, err := stagparser.ParseStruct(user)
}

Index

• func ParseStruct(obj interface{}, tag string) (map[string]map[string]Definition, error)
• func ParseTag(value string, name string) (map[string]Definition, error)
• type Definition
• type ParseError

Functions

func ParseStruct

func ParseStruct(obj interface{}, tag string) (map[string]map[string]Definition, error)

ParseStruct parses struct tags of given object. map key is a field name.

func ParseTag

func ParseTag(value string, name string) (map[string]Definition, error)

ParseTag parses a given tag value.

Types

type Definition

type Definition struct {
	Name       string
	Attributes map[string]any
}

type ParseError

type ParseError interface {
	error
	// Source is a source name
	Source() string

	// Column is a column error occurred
	Column() int

	// Line is a line number error occurred
	Line() int
}

ParseError is an error indicating invalid tag value