Fix empty map or struct convert to another map will return error. (#2863

)

util/gconv/gconv_map.go

@@ -29,22 +29,22 @@ const (
 // tags that will be detected, otherwise it detects the tags in order of:
 // gconv, json, field name.
 func Map(value interface{}, tags ...string) map[string]interface{} {
-	return doMapConvert(value, recursiveTypeAuto, tags...)
+	return doMapConvert(value, recursiveTypeAuto, false, tags...)
 }
 
 // MapDeep does Map function recursively, which means if the attribute of `value`
 // is also a struct/*struct, calls Map function on this attribute converting it to
 // a map[string]interface{} type variable.
 // Also see Map.
 func MapDeep(value interface{}, tags ...string) map[string]interface{} {
-	return doMapConvert(value, recursiveTypeTrue, tags...)
+	return doMapConvert(value, recursiveTypeTrue, false, tags...)
 }
 
 // doMapConvert implements the map converting.
 // It automatically checks and converts json string to map if `value` is string/[]byte.
 //
 // TODO completely implement the recursive converting for all types, especially the map.
-func doMapConvert(value interface{}, recursive recursiveType, tags ...string) map[string]interface{} {
+func doMapConvert(value interface{}, recursive recursiveType, mustMapReturn bool, tags ...string) map[string]interface{} {
 	if value == nil {
 		return nil
 	}
@@ -209,6 +209,7 @@ func doMapConvert(value interface{}, recursive recursiveType, tags ...string) ma
 					RecursiveType:   recursive,
 					RecursiveOption: recursive == recursiveTypeTrue,
 					Tags:            newTags,
+					MustMapReturn:   mustMapReturn,
 				},
 			)
 			if m, ok := convertedValue.(map[string]interface{}); ok {
@@ -228,6 +229,7 @@ type doMapConvertForMapOrStructValueInput struct {
 	RecursiveType   recursiveType // The type from top function entry.
 	RecursiveOption bool          // Whether convert recursively for `current` operation.
 	Tags            []string      // Map key mapping.
+	MustMapReturn   bool          // Must return map instead of Value when empty.
 }
 
 func doMapConvertForMapOrStructValue(in doMapConvertForMapOrStructValueInput) interface{} {
@@ -468,7 +470,7 @@ func doMapConvertForMapOrStructValue(in doMapConvertForMapOrStructValueInput) in
 				}
 			}
 		}
-		if len(dataMap) == 0 {
+		if !in.MustMapReturn && len(dataMap) == 0 {
 			return in.Value
 		}
 		return dataMap

util/gconv/gconv_struct.go

@@ -206,7 +206,7 @@ func doStruct(params interface{}, pointer interface{}, mapping map[string]string
 
 	// paramsMap is the map[string]interface{} type variable for params.
 	// DO NOT use MapDeep here.
-	paramsMap := Map(paramsInterface)
+	paramsMap := doMapConvert(paramsInterface, recursiveTypeAuto, true)
 	if paramsMap == nil {
 		return gerror.NewCodef(
 			gcode.CodeInvalidParameter,

util/gconv/gconv_z_unit_struct_test.go

@@ -1349,3 +1349,53 @@ func Test_Struct_WithCustomType(t *testing.T) {
 		t.Assert(*req2.PayMode, 1000)
 	})
 }
+
+func Test_Struct_EmptyStruct(t *testing.T) {
+	gtest.C(t, func(t *gtest.T) {
+		var err error
+
+		type StructA struct {
+		}
+
+		type StructB struct {
+		}
+
+		var s1 StructA
+		var s2 *StructB
+
+		err = gconv.Scan(s1, &s2)
+		t.AssertNil(err)
+
+		err = gconv.Scan(&s1, &s2)
+		t.AssertNil(err)
+
+		type StructC struct {
+			Val int `json:"val,omitempty"`
+		}
+
+		type StructD struct {
+			Val int
+		}
+
+		var s3 StructC
+		var s4 *StructD
+
+		err = gconv.Scan(s3, &s4)
+		t.AssertNil(err)
+		t.Assert(s4.Val, 0)
+
+		err = gconv.Scan(&s3, &s4)
+		t.AssertNil(err)
+		t.Assert(s4.Val, 0)
+
+		s3.Val = 123
+		err = gconv.Scan(s3, &s4)
+		t.AssertNil(err)
+		t.Assert(s4.Val, 123)
+
+		err = gconv.Scan(&s3, &s4)
+		t.AssertNil(err)
+		t.Assert(s4.Val, 123)
+
+	})
+}