add basic nested binding support (not yet for slices)

bind.go

@@ -36,12 +36,13 @@ func (d *fieldCtxDecoder) Decode(ctx Ctx, reqValue reflect.Value) error {
 }
 
 type fieldTextDecoder struct {
-	index     int
-	fieldName string
-	tag       string // query,param,header,respHeader ...
-	reqField  string
-	dec       bind.TextDecoder
-	get       func(c Ctx, key string, defaultValue ...string) string
+	index       int
+	parentIndex []int
+	fieldName   string
+	tag         string // query,param,header,respHeader ...
+	reqField    string
+	dec         bind.TextDecoder
+	get         func(c Ctx, key string, defaultValue ...string) string
 }
 
 func (d *fieldTextDecoder) Decode(ctx Ctx, reqValue reflect.Value) error {
@@ -50,7 +51,18 @@ func (d *fieldTextDecoder) Decode(ctx Ctx, reqValue reflect.Value) error {
 		return nil
 	}
 
-	err := d.dec.UnmarshalString(text, reqValue.Field(d.index))
+	var err error
+	if len(d.parentIndex) > 0 {
+		for _, i := range d.parentIndex {
+			reqValue = reqValue.Field(i)
+		}
+
+		err = d.dec.UnmarshalString(text, reqValue.Field(d.index))
+
+	} else {
+		err = d.dec.UnmarshalString(text, reqValue.Field(d.index))
+	}
+
 	if err != nil {
 		return fmt.Errorf("unable to decode '%s' as %s: %w", text, d.reqField, err)
 	}

bind_test.go

@@ -38,6 +38,32 @@ func Test_Binder(t *testing.T) {
 	require.Equal(t, "john doe", body.Name)
 }
 
+func Test_Binder_Nested(t *testing.T) {
+	t.Parallel()
+	app := New()
+
+	c := app.NewCtx(&fasthttp.RequestCtx{}).(*DefaultCtx)
+	c.Request().SetBody([]byte(``))
+	c.Request().Header.SetContentType("")
+	c.Request().URI().SetQueryString("name=tom&nested.and.age=10&nested.and.test=john")
+
+	var req struct {
+		Name   string `query:"name"`
+		Nested struct {
+			And struct {
+				Age  int    `query:"age"`
+				Test string `query:"test"`
+			} `query:"and"`
+		} `query:"nested"`
+	}
+
+	err := c.Bind().Req(&req).Err()
+	require.NoError(t, err)
+	require.Equal(t, "tom", req.Name)
+	require.Equal(t, "john", req.Nested.And.Test)
+	require.Equal(t, 10, req.Nested.And.Age)
+}
+
 // go test -run Test_Bind_BasicType -v
 func Test_Bind_BasicType(t *testing.T) {
 	t.Parallel()

binder_compile.go

@@ -45,13 +45,13 @@ func compileReqParser(rt reflect.Type, opt bindCompileOption) (Decoder, error) {
 			continue
 		}
 
-		dec, err := compileFieldDecoder(el.Field(i), i, opt)
+		dec, err := compileFieldDecoder(el.Field(i), i, opt, parentStruct{})
 		if err != nil {
 			return nil, err
 		}
 
 		if dec != nil {
-			decoders = append(decoders, dec)
+			decoders = append(decoders, dec...)
 		}
 	}
 
@@ -67,9 +67,14 @@ func compileReqParser(rt reflect.Type, opt bindCompileOption) (Decoder, error) {
 	}, nil
 }
 
-func compileFieldDecoder(field reflect.StructField, index int, opt bindCompileOption) (decoder, error) {
+type parentStruct struct {
+	tag   string
+	index []int
+}
+
+func compileFieldDecoder(field reflect.StructField, index int, opt bindCompileOption, parent parentStruct) ([]decoder, error) {
 	if reflect.PtrTo(field.Type).Implements(bindUnmarshalerType) {
-		return &fieldCtxDecoder{index: index, fieldName: field.Name, fieldType: field.Type}, nil
+		return []decoder{&fieldCtxDecoder{index: index, fieldName: field.Name, fieldType: field.Type}}, nil
 	}
 
 	var tags = []string{bindTagRespHeader, bindTagQuery, bindTagParam, bindTagHeader, bindTagCookie}
@@ -91,6 +96,10 @@ func compileFieldDecoder(field reflect.StructField, index int, opt bindCompileOp
 
 	tagContent := field.Tag.Get(tagScope)
 
+	if parent.tag != "" {
+		tagContent = parent.tag + "." + tagContent
+	}
+
 	if reflect.PtrTo(field.Type).Implements(textUnmarshalerType) {
 		return compileTextBasedDecoder(field, index, tagScope, tagContent)
 	}
@@ -99,7 +108,38 @@ func compileFieldDecoder(field reflect.StructField, index int, opt bindCompileOp
 		return compileSliceFieldTextBasedDecoder(field, index, tagScope, tagContent)
 	}
 
-	return compileTextBasedDecoder(field, index, tagScope, tagContent)
+	// Nested binding support
+	if field.Type.Kind() == reflect.Struct {
+		var decoders []decoder
+		el := field.Type
+
+		for i := 0; i < el.NumField(); i++ {
+			if !el.Field(i).IsExported() {
+				// ignore unexported field
+				continue
+			}
+			var indexes []int
+			if len(parent.index) > 0 {
+				indexes = append(indexes, parent.index...)
+			}
+			indexes = append(indexes, index)
+			dec, err := compileFieldDecoder(el.Field(i), i, opt, parentStruct{
+				tag:   tagContent,
+				index: indexes,
+			})
+			if err != nil {
+				return nil, err
+			}
+
+			if dec != nil {
+				decoders = append(decoders, dec...)
+			}
+		}
+
+		return decoders, nil
+	}
+
+	return compileTextBasedDecoder(field, index, tagScope, tagContent, parent.index)
 }
 
 func formGetter(ctx Ctx, key string, defaultValue ...string) string {
@@ -120,7 +160,7 @@ func multipartGetter(ctx Ctx, key string, defaultValue ...string) string {
 	return v[0]
 }
 
-func compileTextBasedDecoder(field reflect.StructField, index int, tagScope, tagContent string) (decoder, error) {
+func compileTextBasedDecoder(field reflect.StructField, index int, tagScope, tagContent string, parentIndex ...[]int) ([]decoder, error) {
 	var get func(ctx Ctx, key string, defaultValue ...string) string
 	switch tagScope {
 	case bindTagQuery:
@@ -146,17 +186,23 @@ func compileTextBasedDecoder(field reflect.StructField, index int, tagScope, tag
 		return nil, err
 	}
 
-	return &fieldTextDecoder{
+	fieldDecoder := &fieldTextDecoder{
 		index:     index,
 		fieldName: field.Name,
 		tag:       tagScope,
 		reqField:  tagContent,
 		dec:       textDecoder,
 		get:       get,
-	}, nil
+	}
+
+	if len(parentIndex) > 0 {
+		fieldDecoder.parentIndex = parentIndex[0]
+	}
+
+	return []decoder{fieldDecoder}, nil
 }
 
-func compileSliceFieldTextBasedDecoder(field reflect.StructField, index int, tagScope string, tagContent string) (decoder, error) {
+func compileSliceFieldTextBasedDecoder(field reflect.StructField, index int, tagScope string, tagContent string) ([]decoder, error) {
 	if field.Type.Kind() != reflect.Slice {
 		panic("BUG: unexpected type, expecting slice " + field.Type.String())
 	}
@@ -190,7 +236,7 @@ func compileSliceFieldTextBasedDecoder(field reflect.StructField, index int, tag
 		return nil, errors.New("unexpected tag scope " + strconv.Quote(tagScope))
 	}
 
-	return &fieldSliceDecoder{
+	return []decoder{&fieldSliceDecoder{
 		fieldIndex:     index,
 		eqBytes:        eqBytes,
 		fieldName:      field.Name,
@@ -199,5 +245,5 @@ func compileSliceFieldTextBasedDecoder(field reflect.StructField, index int, tag
 		fieldType:      field.Type,
 		elementType:    et,
 		elementDecoder: elementUnmarshaler,
-	}, nil
+	}}, nil
 }