Fix case sensitivity for nested fields

Author: nikhita

api_tests/config_test.go

@@ -2,9 +2,10 @@ package test
 
 import (
 	"encoding/json"
+	"testing"
+
 	"github.com/json-iterator/go"
 	"github.com/stretchr/testify/require"
-	"testing"
 )
 
 func Test_use_number_for_unmarshal(t *testing.T) {
@@ -45,3 +46,79 @@ func Test_read_large_number_as_interface(t *testing.T) {
 	should.Nil(err)
 	should.Equal(`123456789123456789123456789`, output)
 }
+
+type caseSensitiveStruct struct {
+	A string `json:"a"`
+	B string `json:"b,omitempty"`
+	C *C     `json:"C,omitempty"`
+}
+
+type C struct {
+	D int64 `json:"D,omitempty"`
+	E *E    `json:"e,omitempty"`
+}
+
+type E struct {
+	F string `json:"F,omitempty"`
+}
+
+func Test_CaseSensitive(t *testing.T) {
+	should := require.New(t)
+
+	testCases := []struct {
+		input          string
+		expectedOutput string
+		caseSensitive  bool
+	}{
+		{
+			input:          `{"A":"foo","B":"bar"}`,
+			expectedOutput: `{"a":"foo","b":"bar"}`,
+			caseSensitive:  false,
+		},
+		{
+			input:          `{"a":"foo","b":"bar"}`,
+			expectedOutput: `{"a":"foo","b":"bar"}`,
+			caseSensitive:  true,
+		},
+		{
+			input:          `{"a":"foo","b":"bar","C":{"D":10}}`,
+			expectedOutput: `{"a":"foo","b":"bar","C":{"D":10}}`,
+			caseSensitive:  true,
+		},
+		{
+			input:          `{"a":"foo","B":"bar","c":{"d":10}}`,
+			expectedOutput: `{"a":"foo"}`,
+			caseSensitive:  true,
+		},
+		{
+			input:          `{"a":"foo","C":{"d":10}}`,
+			expectedOutput: `{"a":"foo","C":{}}`,
+			caseSensitive:  true,
+		},
+		{
+			input:          `{"a":"foo","C":{"D":10,"e":{"f":"baz"}}}`,
+			expectedOutput: `{"a":"foo","C":{"D":10,"e":{}}}`,
+			caseSensitive:  true,
+		},
+		{
+			input:          `{"a":"foo","C":{"D":10,"e":{"F":"baz"}}}`,
+			expectedOutput: `{"a":"foo","C":{"D":10,"e":{"F":"baz"}}}`,
+			caseSensitive:  true,
+		},
+		{
+			input:          `{"A":"foo","c":{"d":10,"E":{"f":"baz"}}}`,
+			expectedOutput: `{"a":"foo","C":{"D":10,"e":{"F":"baz"}}}`,
+			caseSensitive:  false,
+		},
+	}
+
+	for _, tc := range testCases {
+		val := caseSensitiveStruct{}
+		err := jsoniter.Config{CaseSensitive: tc.caseSensitive}.Froze().UnmarshalFromString(tc.input, &val)
+		should.Nil(err)
+
+		output, err := jsoniter.MarshalToString(val)
+		should.Nil(err)
+		should.Equal(tc.expectedOutput, output)
+	}
+}

reflect_struct_decoder.go

@@ -32,11 +32,15 @@ func decoderOfStruct(ctx *ctx, typ reflect2.Type) ValDecoder {
 	for k, binding := range bindings {
 		fields[k] = binding.Decoder.(*structFieldDecoder)
 	}
-	for k, binding := range bindings {
-		if _, found := fields[strings.ToLower(k)]; !found {
-			fields[strings.ToLower(k)] = binding.Decoder.(*structFieldDecoder)
+
+	if !ctx.caseSensitive() {
+		for k, binding := range bindings {
+			if _, found := fields[strings.ToLower(k)]; !found {
+				fields[strings.ToLower(k)] = binding.Decoder.(*structFieldDecoder)
+			}
 		}
 	}
+
 	return createStructDecoder(ctx, typ, fields)
 }
 
@@ -47,6 +51,7 @@ func createStructDecoder(ctx *ctx, typ reflect2.Type, fields map[string]*structF
 	knownHash := map[int64]struct{}{
 		0: {},
 	}
+
 	switch len(fields) {
 	case 0:
 		return &skipObjectDecoder{typ}