334 lines
12 KiB
Markdown
334 lines
12 KiB
Markdown
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Package form
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============
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<img align="right" src="https://raw.githubusercontent.com/go-playground/form/master/logo.jpg">
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[](https://github.com/go-playground/form/actions/workflows/workflow.yml)
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[](https://coveralls.io/github/go-playground/form?branch=master)
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[](https://goreportcard.com/report/github.com/go-playground/form)
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[](https://godoc.org/github.com/go-playground/form)
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[](https://gitter.im/go-playground/form?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
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Package form Decodes url.Values into Go value(s) and Encodes Go value(s) into url.Values.
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It has the following features:
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- Supports map of almost all types.
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- Supports both Numbered and Normal arrays eg. `"Array[0]"` and just `"Array"` with multiple values passed.
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- 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.
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- 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.
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- 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.
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- Allows for Custom Type registration.
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- Handles time.Time using RFC3339 time format by default, but can easily be changed by registering a Custom Type, see below.
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- Handles Encoding & Decoding of almost all Go types eg. can Decode into struct, array, map, int... and Encode a struct, array, map, int...
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Common Questions
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- Does it support encoding.TextUnmarshaler? No because TextUnmarshaler only accepts []byte but posted values can have multiple values, so is not suitable.
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- Mixing `array/slice` with `array[idx]/slice[idx]`, in which order are they parsed? `array/slice` then `array[idx]/slice[idx]`
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Supported Types ( out of the box )
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----------
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* `string`
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* `bool`
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* `int`, `int8`, `int16`, `int32`, `int64`
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* `uint`, `uint8`, `uint16`, `uint32`, `uint64`
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* `float32`, `float64`
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* `struct` and `anonymous struct`
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* `interface{}`
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* `time.Time` - by default using RFC3339
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* a `pointer` to one of the above types
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* `slice`, `array`
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* `map`
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* `custom types` can override any of the above types
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* many other types may be supported inherently
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**NOTE**: `map`, `struct` and `slice` nesting are ad infinitum.
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Installation
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------------
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Use go get.
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go get github.com/go-playground/form
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Then import the form package into your own code.
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import "github.com/go-playground/form/v4"
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Usage
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-----
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- Use symbol `.` for separating fields/structs. (eg. `structfield.field`)
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- Use `[index or key]` for access to index of a slice/array or key for map. (eg. `arrayfield[0]`, `mapfield[keyvalue]`)
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```html
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<form method="POST">
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<input type="text" name="Name" value="joeybloggs"/>
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<input type="text" name="Age" value="3"/>
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<input type="text" name="Gender" value="Male"/>
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<input type="text" name="Address[0].Name" value="26 Here Blvd."/>
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<input type="text" name="Address[0].Phone" value="9(999)999-9999"/>
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<input type="text" name="Address[1].Name" value="26 There Blvd."/>
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<input type="text" name="Address[1].Phone" value="1(111)111-1111"/>
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<input type="text" name="active" value="true"/>
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<input type="text" name="MapExample[key]" value="value"/>
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<input type="text" name="NestedMap[key][key]" value="value"/>
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<input type="text" name="NestedArray[0][0]" value="value"/>
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<input type="submit"/>
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</form>
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```
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Examples
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-------
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Decoding
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```go
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package main
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import (
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"fmt"
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"log"
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"net/url"
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"github.com/go-playground/form/v4"
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)
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// Address contains address information
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type Address struct {
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Name string
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Phone string
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}
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// User contains user information
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type User struct {
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Name string
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Age uint8
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Gender string
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Address []Address
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Active bool `form:"active"`
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MapExample map[string]string
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NestedMap map[string]map[string]string
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NestedArray [][]string
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}
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// use a single instance of Decoder, it caches struct info
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var decoder *form.Decoder
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func main() {
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decoder = form.NewDecoder()
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// this simulates the results of http.Request's ParseForm() function
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values := parseForm()
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var user User
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// must pass a pointer
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err := decoder.Decode(&user, values)
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if err != nil {
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log.Panic(err)
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}
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fmt.Printf("%#v\n", user)
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}
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// this simulates the results of http.Request's ParseForm() function
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func parseForm() url.Values {
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return url.Values{
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"Name": []string{"joeybloggs"},
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"Age": []string{"3"},
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"Gender": []string{"Male"},
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"Address[0].Name": []string{"26 Here Blvd."},
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"Address[0].Phone": []string{"9(999)999-9999"},
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"Address[1].Name": []string{"26 There Blvd."},
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"Address[1].Phone": []string{"1(111)111-1111"},
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"active": []string{"true"},
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"MapExample[key]": []string{"value"},
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"NestedMap[key][key]": []string{"value"},
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"NestedArray[0][0]": []string{"value"},
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}
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}
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```
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Encoding
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```go
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package main
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import (
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"fmt"
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"log"
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"github.com/go-playground/form/v4"
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)
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// Address contains address information
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type Address struct {
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Name string
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Phone string
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}
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// User contains user information
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type User struct {
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Name string
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Age uint8
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Gender string
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Address []Address
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Active bool `form:"active"`
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MapExample map[string]string
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NestedMap map[string]map[string]string
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NestedArray [][]string
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}
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// use a single instance of Encoder, it caches struct info
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var encoder *form.Encoder
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func main() {
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encoder = form.NewEncoder()
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user := User{
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Name: "joeybloggs",
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Age: 3,
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Gender: "Male",
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Address: []Address{
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{Name: "26 Here Blvd.", Phone: "9(999)999-9999"},
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{Name: "26 There Blvd.", Phone: "1(111)111-1111"},
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},
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Active: true,
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MapExample: map[string]string{"key": "value"},
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NestedMap: map[string]map[string]string{"key": {"key": "value"}},
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NestedArray: [][]string{{"value"}},
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}
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// must pass a pointer
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values, err := encoder.Encode(&user)
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if err != nil {
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log.Panic(err)
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}
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fmt.Printf("%#v\n", values)
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}
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```
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Registering Custom Types
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--------------
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Decoder
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```go
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decoder.RegisterCustomTypeFunc(func(vals []string) (interface{}, error) {
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return time.Parse("2006-01-02", vals[0])
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}, time.Time{})
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```
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ADDITIONAL: if a struct type is registered, the function will only be called if a url.Value exists for
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the struct and not just the struct fields eg. url.Values{"User":"Name%3Djoeybloggs"} will call the
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custom type function with 'User' as the type, however url.Values{"User.Name":"joeybloggs"} will not.
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Encoder
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```go
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encoder.RegisterCustomTypeFunc(func(x interface{}) ([]string, error) {
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return []string{x.(time.Time).Format("2006-01-02")}, nil
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}, time.Time{})
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```
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Ignoring Fields
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--------------
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you can tell form to ignore fields using `-` in the tag
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```go
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type MyStruct struct {
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Field string `form:"-"`
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}
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```
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Omitempty
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--------------
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you can tell form to omit empty fields using `,omitempty` or `FieldName,omitempty` in the tag
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```go
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type MyStruct struct {
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Field string `form:",omitempty"`
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Field2 string `form:"CustomFieldName,omitempty"`
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}
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```
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Notes
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------
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To maximize compatibility with other systems the Encoder attempts
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to avoid using array indexes in url.Values if at all possible.
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eg.
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```go
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// A struct field of
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Field []string{"1", "2", "3"}
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// will be output a url.Value as
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"Field": []string{"1", "2", "3"}
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and not
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"Field[0]": []string{"1"}
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"Field[1]": []string{"2"}
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"Field[2]": []string{"3"}
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// however there are times where it is unavoidable, like with pointers
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i := int(1)
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Field []*string{nil, nil, &i}
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// to avoid index 1 and 2 must use index
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"Field[2]": []string{"1"}
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```
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Benchmarks
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------
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###### Run on MacBook Pro (15-inch, 2017) using go version go1.10.1 darwin/amd64
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NOTE: the 1 allocation and B/op in the first 4 decodes is actually the struct allocating when passing it in, so primitives are actually zero allocation.
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```go
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go test -run=NONE -bench=. -benchmem=true
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goos: darwin
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goarch: amd64
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pkg: github.com/go-playground/form/benchmarks
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BenchmarkSimpleUserDecodeStruct-8 5000000 236 ns/op 64 B/op 1 allocs/op
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BenchmarkSimpleUserDecodeStructParallel-8 20000000 82.1 ns/op 64 B/op 1 allocs/op
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BenchmarkSimpleUserEncodeStruct-8 2000000 627 ns/op 485 B/op 10 allocs/op
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BenchmarkSimpleUserEncodeStructParallel-8 10000000 223 ns/op 485 B/op 10 allocs/op
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BenchmarkPrimitivesDecodeStructAllPrimitivesTypes-8 2000000 724 ns/op 96 B/op 1 allocs/op
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BenchmarkPrimitivesDecodeStructAllPrimitivesTypesParallel-8 10000000 246 ns/op 96 B/op 1 allocs/op
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BenchmarkPrimitivesEncodeStructAllPrimitivesTypes-8 500000 3187 ns/op 2977 B/op 36 allocs/op
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BenchmarkPrimitivesEncodeStructAllPrimitivesTypesParallel-8 1000000 1106 ns/op 2977 B/op 36 allocs/op
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BenchmarkComplexArrayDecodeStructAllTypes-8 100000 13748 ns/op 2248 B/op 121 allocs/op
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BenchmarkComplexArrayDecodeStructAllTypesParallel-8 500000 4313 ns/op 2249 B/op 121 allocs/op
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BenchmarkComplexArrayEncodeStructAllTypes-8 200000 10758 ns/op 7113 B/op 104 allocs/op
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BenchmarkComplexArrayEncodeStructAllTypesParallel-8 500000 3532 ns/op 7113 B/op 104 allocs/op
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BenchmarkComplexMapDecodeStructAllTypes-8 100000 17644 ns/op 5305 B/op 130 allocs/op
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BenchmarkComplexMapDecodeStructAllTypesParallel-8 300000 5470 ns/op 5308 B/op 130 allocs/op
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BenchmarkComplexMapEncodeStructAllTypes-8 200000 11155 ns/op 6971 B/op 129 allocs/op
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BenchmarkComplexMapEncodeStructAllTypesParallel-8 500000 3768 ns/op 6971 B/op 129 allocs/op
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BenchmarkDecodeNestedStruct-8 500000 2462 ns/op 384 B/op 14 allocs/op
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BenchmarkDecodeNestedStructParallel-8 2000000 814 ns/op 384 B/op 14 allocs/op
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BenchmarkEncodeNestedStruct-8 1000000 1483 ns/op 693 B/op 16 allocs/op
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BenchmarkEncodeNestedStructParallel-8 3000000 525 ns/op 693 B/op 16 allocs/op
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```
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Competitor benchmarks can be found [here](https://github.com/go-playground/form/blob/master/benchmarks/benchmarks.md)
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Complimentary Software
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----------------------
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Here is a list of software that compliments using this library post decoding.
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* [Validator](https://github.com/go-playground/validator) - Go Struct and Field validation, including Cross Field, Cross Struct, Map, Slice and Array diving.
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* [mold](https://github.com/go-playground/mold) - Is a general library to help modify or set data within data structures and other objects.
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Package Versioning
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----------
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I'm jumping on the vendoring bandwagon, you should vendor this package as I will not
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be creating different version with gopkg.in like allot of my other libraries.
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Why? because my time is spread pretty thin maintaining all of the libraries I have + LIFE,
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it is so freeing not to worry about it and will help me keep pouring out bigger and better
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things for you the community.
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License
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------
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Distributed under MIT License, please see license file in code for more details.
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