Thanks to vkd for suggestions, modifying code

binding/binding_test.go

@@ -667,6 +667,22 @@ func TestExistsFails(t *testing.T) {
 	assert.Error(t, err)
 }
 
+func TestHeaderBinding(t *testing.T) {
+	h := Header
+	assert.Equal(t, "header", h.Name())
+
+	type tHeader struct {
+		Limit int `header:"limit"`
+	}
+
+	var theader tHeader
+	req := requestWithBody("GET", "/", "")
+	req.Header.Add("limit", "1000")
+	assert.NoError(t, h.Bind(req, &theader))
+	assert.Equal(t, 1000, theader.Limit)
+
+}
+
 func TestUriBinding(t *testing.T) {
 	b := Uri
 	assert.Equal(t, "uri", b.Name())

binding/form_mapping.go

@@ -7,7 +7,6 @@ package binding
 import (
 	"errors"
 	"fmt"
-	"net/textproto"
 	"reflect"
 	"strconv"
 	"strings"
@@ -22,10 +21,6 @@ func mapUri(ptr interface{}, m map[string][]string) error {
 	return mapFormByTag(ptr, m, "uri")
 }
 
-func mapHeader(ptr interface{}, m map[string][]string) error {
-	return mapFormByTag(ptr, m, "header")
-}
-
 func mapForm(ptr interface{}, form map[string][]string) error {
 	return mapFormByTag(ptr, form, "form")
 }
@@ -107,7 +102,6 @@ func mapping(value reflect.Value, field reflect.StructField, setter setter, tag
 
 type setOptions struct {
 	isDefaultExists bool
-	isHeader        bool
 	defaultValue    string
 }
 
@@ -129,7 +123,6 @@ func tryToSetValue(value reflect.Value, field reflect.StructField, setter setter
 	}
 
 	var opt string
-	setOpt.isHeader = tag == "header"
 	for len(opts) > 0 {
 		opt, opts = head(opts, ",")
 
@@ -143,17 +136,7 @@ func tryToSetValue(value reflect.Value, field reflect.StructField, setter setter
 }
 
 func setByForm(value reflect.Value, field reflect.StructField, form map[string][]string, tagValue string, opt setOptions) (isSetted bool, err error) {
-	var (
+	vs, ok := form[tagValue]
-		vs []string
-		ok bool
-	)
-
-	if opt.isHeader {
-		vs, ok = form[textproto.CanonicalMIMEHeaderKey(tagValue)]
-	} else {
-		vs, ok = form[tagValue]
-	}
-
 	if !ok && !opt.isDefaultExists {
 		return false, nil
 	}

binding/header.go

@@ -1,6 +1,10 @@
 package binding
 
-import "net/http"
+import (
+	"net/http"
+	"net/textproto"
+	"reflect"
+)
 
 type headerBinding struct{}
 
@@ -16,3 +20,15 @@ func (headerBinding) Bind(req *http.Request, obj interface{}) error {
 
 	return validate(obj)
 }
+
+func mapHeader(ptr interface{}, h map[string][]string) error {
+	return mappingByPtr(ptr, headerSource(h), "header")
+}
+
+type headerSource map[string][]string
+
+//var _ setter = headerSource(nil)
+
+func (hs headerSource) TrySet(value reflect.Value, field reflect.StructField, tagValue string, opt setOptions) (isSetted bool, err error) {
+	return setByForm(value, field, hs, textproto.CanonicalMIMEHeaderKey(tagValue), opt)
+}