From 45f30c0be3420c17a3b002025e346ceb8ce8313d Mon Sep 17 00:00:00 2001
From: Vasiliy Tolstov <v.tolstov@unistack.org>
Date: Tue, 26 Oct 2021 14:12:37 +0300
Subject: [PATCH] util/reflect: ZeroFieldByPath and SetFieldByPath

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>
---
 util/reflect/struct.go      | 26 ++++++++++++++++++++++++--
 util/reflect/struct_test.go | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/util/reflect/struct.go b/util/reflect/struct.go
index 0f580be8..54b0d400 100644
--- a/util/reflect/struct.go
+++ b/util/reflect/struct.go
@@ -72,9 +72,10 @@ func StructFieldByTag(src interface{}, tkey string, tval string) (interface{}, e
 // ZeroFieldByPath clean struct field by its path
 func ZeroFieldByPath(src interface{}, path string) error {
 	var err error
-	var val reflect.Value
+	val := reflect.ValueOf(src)
+
 	for _, p := range strings.Split(path, ".") {
-		val, err = structValueByName(reflect.ValueOf(src), p)
+		val, err = structValueByName(reflect.ValueOf(val), p)
 		if err != nil {
 			return err
 		}
@@ -93,6 +94,27 @@ func ZeroFieldByPath(src interface{}, path string) error {
 	return nil
 }
 
+// SetFieldByPath set struct field by its path
+func SetFieldByPath(src interface{}, dst interface{}, path string) error {
+	var err error
+	val := reflect.ValueOf(src)
+
+	for _, p := range strings.Split(path, ".") {
+		val, err = structValueByName(val, p)
+		if err != nil {
+			return err
+		}
+	}
+
+	if !val.CanSet() {
+		return ErrInvalidStruct
+	}
+
+	val.Set(reflect.ValueOf(dst))
+
+	return nil
+}
+
 // structValueByName get struct field by its name
 func structValueByName(sv reflect.Value, tkey string) (reflect.Value, error) {
 	if sv.Kind() == reflect.Ptr {
diff --git a/util/reflect/struct_test.go b/util/reflect/struct_test.go
index 85f5019b..48476f88 100644
--- a/util/reflect/struct_test.go
+++ b/util/reflect/struct_test.go
@@ -8,6 +8,40 @@ import (
 	rutil "go.unistack.org/micro/v3/util/reflect"
 )
 
+func TestSetFieldByPath(t *testing.T) {
+	type NestedStr struct {
+		BBB string
+		CCC int
+	}
+	type Str1 struct {
+		Name   []string `json:"name" codec:"flatten"`
+		XXX    string   `json:"xxx"`
+		Nested NestedStr
+	}
+	type Str2 struct {
+		XXX    string `json:"xxx"`
+		Nested *NestedStr
+		Name   []string `json:"name" codec:"flatten"`
+	}
+	var err error
+	val1 := &Str1{Name: []string{"first", "second"}, XXX: "ttt", Nested: NestedStr{BBB: "ddd", CCC: 9}}
+	val2 := &Str2{Name: []string{"first", "second"}, XXX: "ttt", Nested: &NestedStr{BBB: "ddd", CCC: 9}}
+	err = rutil.SetFieldByPath(val1, "xxx", "Nested.BBB")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if val1.Nested.BBB != "xxx" {
+		t.Fatalf("SetFieldByPath not works: %#+v", val1)
+	}
+	err = rutil.SetFieldByPath(val2, "xxx", "Nested.BBB")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if val2.Nested.BBB != "xxx" {
+		t.Fatalf("SetFieldByPath not works: %#+v", val1)
+	}
+}
+
 func TestZeroFieldByPath(t *testing.T) {
 	type NestedStr struct {
 		BBB string