support bind uri param (#1612)

* support bind uri (1)

* uri binding successful run

* fix vet warning: github.com/gin-gonic/gin/internal.Param composite literal uses unkeyed fields

* fix code style

* update function name

* fix test function signature

* add test for CanSet

* update readme and add test case

* remove internal.Params

* add coverage

* fix warning

binding/binding.go

@@ -36,6 +36,13 @@ 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
@@ -70,6 +77,7 @@ var (
 	ProtoBuf      = protobufBinding{}
 	MsgPack       = msgpackBinding{}
 	YAML          = yamlBinding{}
+	Uri           = uriBinding{}
 )
 
 // Default returns the appropriate Binding instance based on the HTTP method

binding/binding_test.go

@@ -662,6 +662,27 @@ func TestExistsFails(t *testing.T) {
 	assert.Error(t, err)
 }
 
+func TestUriBinding(t *testing.T) {
+	b := Uri
+	assert.Equal(t, "uri", b.Name())
+
+	type Tag struct {
+		Name string `uri:"name"`
+	}
+	var tag Tag
+	m := make(map[string][]string)
+	m["name"] = []string{"thinkerou"}
+	assert.NoError(t, b.BindUri(m, &tag))
+	assert.Equal(t, "thinkerou", tag.Name)
+
+	type NotSupportStruct struct {
+		Name map[string]interface{} `uri:"name"`
+	}
+	var not NotSupportStruct
+	assert.Error(t, b.BindUri(m, &not))
+	assert.Equal(t, "", not.Name)
+}
+
 func testFormBinding(t *testing.T, method, path, badPath, body, badBody string) {
 	b := Form
 	assert.Equal(t, "form", b.Name())
@@ -1232,3 +1253,12 @@ func requestWithBody(method, path, body string) (req *http.Request) {
 	req, _ = http.NewRequest(method, path, bytes.NewBufferString(body))
 	return
 }
+
+func TestCanSet(t *testing.T) {
+	type CanSetStruct struct {
+		lowerStart string `form:"lower"`
+	}
+
+	var c CanSetStruct
+	assert.Nil(t, mapForm(&c, nil))
+}

binding/form_mapping.go

@@ -12,7 +12,15 @@ import (
 	"time"
 )
 
+func mapUri(ptr interface{}, m map[string][]string) error {
+	return mapFormByTag(ptr, m, "uri")
+}
+
 func mapForm(ptr interface{}, form map[string][]string) error {
+	return mapFormByTag(ptr, form, "form")
+}
+
+func mapFormByTag(ptr interface{}, form map[string][]string, tag string) error {
 	typ := reflect.TypeOf(ptr).Elem()
 	val := reflect.ValueOf(ptr).Elem()
 	for i := 0; i < typ.NumField(); i++ {
@@ -23,7 +31,7 @@ func mapForm(ptr interface{}, form map[string][]string) error {
 		}
 
 		structFieldKind := structField.Kind()
-		inputFieldName := typeField.Tag.Get("form")
+		inputFieldName := typeField.Tag.Get(tag)
 		inputFieldNameList := strings.Split(inputFieldName, ",")
 		inputFieldName = inputFieldNameList[0]
 		var defaultValue string

binding/uri.go

@@ -0,0 +1,18 @@
+// Copyright 2018 Gin Core Team.  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
+
+type uriBinding struct{}
+
+func (uriBinding) Name() string {
+	return "uri"
+}
+
+func (uriBinding) BindUri(m map[string][]string, obj interface{}) error {
+	if err := mapUri(obj, m); err != nil {
+		return err
+	}
+	return validate(obj)
+}