form – github.com/go-playground/form Index | Files | Directories

package form

import "github.com/go-playground/form"

Package form Decodes url.Values into Go value(s) and Encodes Go value(s) into url.Values.

It has the following features:

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.

Supported Types

out of the box supported types

Usage

symbols

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

Functions

func ExtractType 

func ExtractType(current reflect.Value) (reflect.Value, reflect.Kind)

ExtractType gets the actual underlying type of field value. it is exposed for use within you Custom 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 

type DecodeCustomTypeFunc func([]string) (interface{}, error)

DecodeCustomTypeFunc allows for registering/overriding types to be parsed.

type DecodeErrors 

type DecodeErrors map[string]error

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 

func (d *Decoder) Decode(v interface{}, values url.Values) (err error)

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 

func (d *Decoder) SetMaxArraySize(size uint)

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) SetMode 

func (d *Decoder) SetMode(mode Mode)

SetMode sets the mode the decoder should run Default is ModeImplicit

func (*Decoder) SetTagName 

func (d *Decoder) SetTagName(tagName string)

SetTagName sets the given tag name to be used by the decoder. Default is "form"

type EncodeCustomTypeFunc 

type EncodeCustomTypeFunc func(x interface{}) ([]string, error)

EncodeCustomTypeFunc allows for registering/overriding types to be parsed.

type EncodeErrors 

type EncodeErrors map[string]error

EncodeErrors is a map of errors encountered during form encoding

func (EncodeErrors) Error 

func (e EncodeErrors) Error() string

type Encoder 

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

Encoder is the main encode instance

func NewEncoder 

func NewEncoder() *Encoder

NewEncoder creates a new encoder instance with sane defaults

func (*Encoder) Encode 

func (e *Encoder) Encode(v interface{}) (values url.Values, err error)

Encode encodes the given values and sets the corresponding struct values

func (*Encoder) RegisterCustomTypeFunc 

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) SetMode 

func (e *Encoder) SetMode(mode Mode)

SetMode sets the mode the encoder should run Default is ModeImplicit

func (*Encoder) SetTagName 

func (e *Encoder) SetTagName(tagName string)

SetTagName sets the given tag name to be used by the encoder. Default is "form"

type InvalidDecoderError 

type InvalidDecoderError struct {
	Type reflect.Type
}

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 

type InvalidEncodeError struct {
	Type reflect.Type
}

An InvalidEncodeError describes an invalid argument passed to Encode.

func (*InvalidEncodeError) Error 

func (e *InvalidEncodeError) Error() string

type Mode 

type Mode uint8

Mode specifies which mode the form decoder is to run 

const (

	// ModeImplicit tries to parse values for all
	// fields that do not have an ignore '-' tag
	ModeImplicit Mode = iota

	// ModeExplicit only parses values for field with a field tag
	// and that tag is not the ignore '-' tag
	ModeExplicit
)

type TagNameFunc 

type TagNameFunc func(field reflect.StructField) string

TagNameFunc allows for adding of a custom tag name parser

Source Files

cache.go decoder.go doc.go encoder.go form.go form_decoder.go form_encoder.go util.go

Directories

PathSynopsis
benchmarks
_examples
_examples/decoder
_examples/decoder-embedded
_examples/encoder
_examples/encoder-embedded
_examples/encoder-omitempty
Version
v3.0.0+incompatible
Published
Jul 31, 2017
Platform
js/wasm
Imports
11 packages
Last checked
now –

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