[StructUtil] add support that the Struct can nest any type to transform (#80)

* add support json tag attribute for StructToMap function

* add the structutil to provide more rich functions and fixed #77

* add support that the nested struct to map for structutil

* recover code

* add structutil unit test

* [StructUtil] add unit test

structutil/struct_test.go

@@ -2,11 +2,18 @@ package structutil
 
 import (
 	"github.com/duke-git/lancet/v2/internal"
+	"reflect"
 	"testing"
 )
 
-func TestToMap(t *testing.T) {
-	assert := internal.NewAssert(t, "TestStructToMap")
+func TestStruct_ToMap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStruct_ToMap")
+
+	t.Run("no struct", func(t *testing.T) {
+		m, _ := ToMap(1)
+		var expected map[string]any
+		assert.Equal(expected, m)
+	})
 
 	t.Run("StructToMap", func(_ *testing.T) {
 		type People struct {
@@ -55,3 +62,69 @@ func TestToMap(t *testing.T) {
 		assert.Equal(expect2, p2m)
 	})
 }
+
+func TestStruct_Fields(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStruct_Fields")
+
+	type Parent struct {
+		A string         `json:"a"`
+		B int            `json:"b"`
+		C []string       `json:"c"`
+		D map[string]any `json:"d"`
+	}
+
+	p1 := &Parent{
+		A: "1",
+		B: 11,
+		C: []string{"11", "22"},
+		D: map[string]any{"d1": 1, "d2": 2},
+	}
+
+	s := New(p1)
+	fields := s.Fields()
+	assert.Equal(4, len(fields))
+	assert.Equal(reflect.String, fields[0].Kind())
+	assert.Equal(reflect.Int, fields[1].Kind())
+	assert.Equal(reflect.Slice, fields[2].Kind())
+	assert.Equal(reflect.Map, fields[3].Kind())
+}
+
+func TestStruct_Field(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStruct_Field")
+
+	type Parent struct {
+		A string         `json:"a"`
+		B int            `json:"b"`
+		C []string       `json:"c"`
+		D map[string]any `json:"d"`
+	}
+
+	p1 := &Parent{
+		A: "1",
+		B: 11,
+		C: []string{"11", "22"},
+		D: map[string]any{"d1": 1, "d2": 2},
+	}
+
+	s := New(p1)
+	a, ok := s.Field("A")
+	assert.Equal(true, ok)
+	assert.Equal(reflect.String, a.Kind())
+	assert.Equal("1", a.Value())
+	assert.Equal("a", a.tag.Name)
+	assert.Equal(false, a.tag.HasOption("omitempty"))
+}
+
+func TestStruct_IsStruct(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStruct_Field")
+
+	type Test1 struct{}
+	t1 := &Test1{}
+	t2 := 1
+
+	s1 := New(t1)
+	s2 := New(t2)
+
+	assert.Equal(true, s1.IsStruct())
+	assert.Equal(false, s2.IsStruct())
+}