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// Copyright 2014 Manu Martinez-Almeida. All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.
package binding
import "net/http"
// Content-Type MIME of the most common data formats.
const (
MIMEJSON = "application/json"
MIMEHTML = "text/html"
MIMEXML = "application/xml"
MIMEXML2 = "text/xml"
MIMEPlain = "text/plain"
MIMEPOSTForm = "application/x-www-form-urlencoded"
MIMEMultipartPOSTForm = "multipart/form-data"
MIMEPROTOBUF = "application/x-protobuf"
MIMEMSGPACK = "application/x-msgpack"
MIMEMSGPACK2 = "application/msgpack"
MIMEYAML = "application/x-yaml"
// Binding describes the interface which needs to be implemented for binding the
// data present in the request such as JSON request body, query parameters or
// the form POST.
type Binding interface {
Name() string
Bind(*http.Request, interface{}) error
// BindingBody adds BindBody method to Binding. BindBody is similar with Bind,
// but it reads the body from supplied bytes instead of req.Body.
type BindingBody interface {
BindBody([]byte, interface{}) error
// BindingUri adds BindUri method to Binding. BindUri is similar with Bind,
// but it read the Params.
type BindingUri interface {
Name() string
BindUri(map[string][]string, interface{}) error
// StructValidator is the minimal interface which needs to be implemented in
// order for it to be used as the validator engine for ensuring the correctness
// of the request. Gin provides a default implementation for this using
type StructValidator interface {
// ValidateStruct can receive any kind of type and it should never panic, even if the configuration is not right.
// If the received type is not a struct, any validation should be skipped and nil must be returned.
// If the received type is a struct or pointer to a struct, the validation should be performed.
// If the struct is not valid or the validation itself fails, a descriptive error should be returned.
// Otherwise nil must be returned.
ValidateStruct(interface{}) error
// Engine returns the underlying validator engine which powers the
// StructValidator implementation.
Engine() interface{}
// Validator is the default validator which implements the StructValidator
// interface. It uses
// under the hood.
var Validator StructValidator = &defaultValidator{}
// These implement the Binding interface and can be used to bind the data
// present in the request to struct instances.
var (
JSON = jsonBinding{}
XML = xmlBinding{}
Form = formBinding{}
Query = queryBinding{}
FormPost = formPostBinding{}
FormMultipart = formMultipartBinding{}
ProtoBuf = protobufBinding{}
MsgPack = msgpackBinding{}
YAML = yamlBinding{}
Uri = uriBinding{}
// Default returns the appropriate Binding instance based on the HTTP method
// and the content type.
func Default(method, contentType string) Binding {
if method == "GET" {
return Form
switch contentType {
return JSON
return XML
return ProtoBuf
return MsgPack
return YAML
default: //case MIMEPOSTForm, MIMEMultipartPOSTForm:
return Form
func validate(obj interface{}) error {
if Validator == nil {
return nil
return Validator.ValidateStruct(obj)