Adding a new config to DefaultBinder

Now the DefaultBinder could be configured to avoid binding struct fields
by name. This is particularly useful when the user don't want to bind
certain struct fields (with this config in true, only the tagged fields
will be binded)

Fixes labstack#1620, fixes labstack#1631, partially fixes labstack#1670

bind.go

@@ -19,7 +19,11 @@ type (
 	}
 
 	// DefaultBinder is the default implementation of the Binder interface.
-	DefaultBinder struct{}
+	DefaultBinder struct {
+		// AvoidBindByFieldName avoid binding struct fields by name automatically. If it's set to true, the binding is
+		// only performed when a valid tag is pressent
+		AvoidBindByFieldName bool
+	}
 
 	// BindUnmarshaler is the interface used to wrap the UnmarshalParam method.
 	// Types that don't implement this, but do implement encoding.TextUnmarshaler
@@ -113,13 +117,14 @@ func (b *DefaultBinder) bindData(ptr interface{}, data map[string][]string, tag
 		inputFieldName := typeField.Tag.Get(tag)
 
 		if inputFieldName == "" {
-			inputFieldName = typeField.Name
 			// If tag is nil, we inspect if the field is a struct.
 			if _, ok := structField.Addr().Interface().(BindUnmarshaler); !ok && structFieldKind == reflect.Struct {
 				if err := b.bindData(structField.Addr().Interface(), data, tag); err != nil {
 					return err
 				}
 				continue
+			} else if b.AvoidBindByFieldName == false {
+				inputFieldName = typeField.Name
 			}
 		}
 

bind_test.go

@@ -330,6 +330,23 @@ func TestBindbindData(t *testing.T) {
 	assertBindTestStruct(assert, ts)
 }
 
+func TestBindbindDataByTags(t *testing.T) {
+	assert := assert.New(t)
+	ts := new(bindTestStructWithTags)
+	b := new(DefaultBinder)
+	b.bindData(ts, values, "form")
+	assertBindTestStruct(assert, (*bindTestStruct)(ts))
+}
+
+func TestBindbindDataAvoidBindByFieldName(t *testing.T) {
+	assert := assert.New(t)
+	ts := new(bindTestStruct)
+	b := new(DefaultBinder)
+	b.AvoidBindByFieldName = true
+	b.bindData(ts, values, "form")
+	assertBindTestStructDefaultValues(assert, ts)
+}
+
 func TestBindParam(t *testing.T) {
 	e := New()
 	req := httptest.NewRequest(GET, "/", nil)
@@ -516,6 +533,24 @@ func assertBindTestStruct(a *assert.Assertions, ts *bindTestStruct) {
 	a.Equal("", ts.GetCantSet())
 }
 
+func assertBindTestStructDefaultValues(a *assert.Assertions, ts *bindTestStruct) {
+	a.Equal(0, ts.I)
+	a.Equal(int8(0), ts.I8)
+	a.Equal(int16(0), ts.I16)
+	a.Equal(int32(0), ts.I32)
+	a.Equal(int64(0), ts.I64)
+	a.Equal(uint(0), ts.UI)
+	a.Equal(uint8(0), ts.UI8)
+	a.Equal(uint16(0), ts.UI16)
+	a.Equal(uint32(0), ts.UI32)
+	a.Equal(uint64(0), ts.UI64)
+	a.Equal(false, ts.B)
+	a.Equal(float32(0), ts.F32)
+	a.Equal(float64(0), ts.F64)
+	a.Equal("", ts.S)
+	a.Equal("", ts.GetCantSet())
+}
+
 func testBindOkay(assert *assert.Assertions, r io.Reader, ctype string) {
 	e := New()
 	req := httptest.NewRequest(http.MethodPost, "/", r)