gotosocial/vendor/github.com/go-playground/form/v4/doc.go

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/*
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/v4"
)
// 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/v4"
)
// 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"}
*/
package form