[golang] Add support for text parsing with json struct tags (#7353)

* [golang] Add support for text parsing with json struct tags

Add struct tags to Go native structs generated when object API is used.

This allows to use the same JSON file as for C++ text
parsing(i.e. snake_case vs CamelCase) and thus enabling text parsing
for Go(when using object API).

* [golang] Add test for text parsing

Added small test to check and demonstrate text parsing in Go.
Also, ran clang-format on cpp file changes.

src/idl_gen_go.cpp

@@ -842,7 +842,8 @@ class GoGenerator : public BaseGenerator {
         continue;
       code += "\t" + namer_.Field(field) + " ";
       if (field.IsScalarOptional()) { code += "*"; }
-      code += NativeType(field.value.type) + "\n";
+      code += NativeType(field.value.type) + " `json:\"" + field.name + "\"`" +
+              "\n";
     }
     code += "}\n\n";
 

tests/MyGame/Example/Ability.go

@@ -7,8 +7,8 @@ import (
 )
 
 type AbilityT struct {
-	Id uint32
+	Id uint32 `json:"id"`
-	Distance uint32
+	Distance uint32 `json:"distance"`
 }
 
 func (t *AbilityT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/Monster.go

@@ -10,56 +10,56 @@ import (
 
 /// an example documentation comment: "monster object"
 type MonsterT struct {
-	Pos *Vec3T
+	Pos *Vec3T `json:"pos"`
-	Mana int16
+	Mana int16 `json:"mana"`
-	Hp int16
+	Hp int16 `json:"hp"`
-	Name string
+	Name string `json:"name"`
-	Inventory []byte
+	Inventory []byte `json:"inventory"`
-	Color Color
+	Color Color `json:"color"`
-	Test *AnyT
+	Test *AnyT `json:"test"`
-	Test4 []*TestT
+	Test4 []*TestT `json:"test4"`
-	Testarrayofstring []string
+	Testarrayofstring []string `json:"testarrayofstring"`
-	Testarrayoftables []*MonsterT
+	Testarrayoftables []*MonsterT `json:"testarrayoftables"`
-	Enemy *MonsterT
+	Enemy *MonsterT `json:"enemy"`
-	Testnestedflatbuffer []byte
+	Testnestedflatbuffer []byte `json:"testnestedflatbuffer"`
-	Testempty *StatT
+	Testempty *StatT `json:"testempty"`
-	Testbool bool
+	Testbool bool `json:"testbool"`
-	Testhashs32Fnv1 int32
+	Testhashs32Fnv1 int32 `json:"testhashs32_fnv1"`
-	Testhashu32Fnv1 uint32
+	Testhashu32Fnv1 uint32 `json:"testhashu32_fnv1"`
-	Testhashs64Fnv1 int64
+	Testhashs64Fnv1 int64 `json:"testhashs64_fnv1"`
-	Testhashu64Fnv1 uint64
+	Testhashu64Fnv1 uint64 `json:"testhashu64_fnv1"`
-	Testhashs32Fnv1a int32
+	Testhashs32Fnv1a int32 `json:"testhashs32_fnv1a"`
-	Testhashu32Fnv1a uint32
+	Testhashu32Fnv1a uint32 `json:"testhashu32_fnv1a"`
-	Testhashs64Fnv1a int64
+	Testhashs64Fnv1a int64 `json:"testhashs64_fnv1a"`
-	Testhashu64Fnv1a uint64
+	Testhashu64Fnv1a uint64 `json:"testhashu64_fnv1a"`
-	Testarrayofbools []bool
+	Testarrayofbools []bool `json:"testarrayofbools"`
-	Testf float32
+	Testf float32 `json:"testf"`
-	Testf2 float32
+	Testf2 float32 `json:"testf2"`
-	Testf3 float32
+	Testf3 float32 `json:"testf3"`
-	Testarrayofstring2 []string
+	Testarrayofstring2 []string `json:"testarrayofstring2"`
-	Testarrayofsortedstruct []*AbilityT
+	Testarrayofsortedstruct []*AbilityT `json:"testarrayofsortedstruct"`
-	Flex []byte
+	Flex []byte `json:"flex"`
-	Test5 []*TestT
+	Test5 []*TestT `json:"test5"`
-	VectorOfLongs []int64
+	VectorOfLongs []int64 `json:"vector_of_longs"`
-	VectorOfDoubles []float64
+	VectorOfDoubles []float64 `json:"vector_of_doubles"`
-	ParentNamespaceTest *MyGame.InParentNamespaceT
+	ParentNamespaceTest *MyGame.InParentNamespaceT `json:"parent_namespace_test"`
-	VectorOfReferrables []*ReferrableT
+	VectorOfReferrables []*ReferrableT `json:"vector_of_referrables"`
-	SingleWeakReference uint64
+	SingleWeakReference uint64 `json:"single_weak_reference"`
-	VectorOfWeakReferences []uint64
+	VectorOfWeakReferences []uint64 `json:"vector_of_weak_references"`
-	VectorOfStrongReferrables []*ReferrableT
+	VectorOfStrongReferrables []*ReferrableT `json:"vector_of_strong_referrables"`
-	CoOwningReference uint64
+	CoOwningReference uint64 `json:"co_owning_reference"`
-	VectorOfCoOwningReferences []uint64
+	VectorOfCoOwningReferences []uint64 `json:"vector_of_co_owning_references"`
-	NonOwningReference uint64
+	NonOwningReference uint64 `json:"non_owning_reference"`
-	VectorOfNonOwningReferences []uint64
+	VectorOfNonOwningReferences []uint64 `json:"vector_of_non_owning_references"`
-	AnyUnique *AnyUniqueAliasesT
+	AnyUnique *AnyUniqueAliasesT `json:"any_unique"`
-	AnyAmbiguous *AnyAmbiguousAliasesT
+	AnyAmbiguous *AnyAmbiguousAliasesT `json:"any_ambiguous"`
-	VectorOfEnums []Color
+	VectorOfEnums []Color `json:"vector_of_enums"`
-	SignedEnum Race
+	SignedEnum Race `json:"signed_enum"`
-	Testrequirednestedflatbuffer []byte
+	Testrequirednestedflatbuffer []byte `json:"testrequirednestedflatbuffer"`
-	ScalarKeySortedTables []*StatT
+	ScalarKeySortedTables []*StatT `json:"scalar_key_sorted_tables"`
-	NativeInline *TestT
+	NativeInline *TestT `json:"native_inline"`
-	LongEnumNonEnumDefault LongEnum
+	LongEnumNonEnumDefault LongEnum `json:"long_enum_non_enum_default"`
-	LongEnumNormalDefault LongEnum
+	LongEnumNormalDefault LongEnum `json:"long_enum_normal_default"`
 }
 
 func (t *MonsterT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/Referrable.go

@@ -7,7 +7,7 @@ import (
 )
 
 type ReferrableT struct {
-	Id uint64
+	Id uint64 `json:"id"`
 }
 
 func (t *ReferrableT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/Stat.go

@@ -7,9 +7,9 @@ import (
 )
 
 type StatT struct {
-	Id string
+	Id string `json:"id"`
-	Val int64
+	Val int64 `json:"val"`
-	Count uint16
+	Count uint16 `json:"count"`
 }
 
 func (t *StatT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/StructOfStructs.go

@@ -7,9 +7,9 @@ import (
 )
 
 type StructOfStructsT struct {
-	A *AbilityT
+	A *AbilityT `json:"a"`
-	B *TestT
+	B *TestT `json:"b"`
-	C *AbilityT
+	C *AbilityT `json:"c"`
 }
 
 func (t *StructOfStructsT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/StructOfStructsOfStructs.go

@@ -7,7 +7,7 @@ import (
 )
 
 type StructOfStructsOfStructsT struct {
-	A *StructOfStructsT
+	A *StructOfStructsT `json:"a"`
 }
 
 func (t *StructOfStructsOfStructsT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/Test.go

@@ -7,8 +7,8 @@ import (
 )
 
 type TestT struct {
-	A int16
+	A int16 `json:"a"`
-	B int8
+	B int8 `json:"b"`
 }
 
 func (t *TestT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/TestSimpleTableWithEnum.go

@@ -7,7 +7,7 @@ import (
 )
 
 type TestSimpleTableWithEnumT struct {
-	Color Color
+	Color Color `json:"color"`
 }
 
 func (t *TestSimpleTableWithEnumT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/TypeAliases.go

@@ -7,18 +7,18 @@ import (
 )
 
 type TypeAliasesT struct {
-	I8 int8
+	I8 int8 `json:"i8"`
-	U8 byte
+	U8 byte `json:"u8"`
-	I16 int16
+	I16 int16 `json:"i16"`
-	U16 uint16
+	U16 uint16 `json:"u16"`
-	I32 int32
+	I32 int32 `json:"i32"`
-	U32 uint32
+	U32 uint32 `json:"u32"`
-	I64 int64
+	I64 int64 `json:"i64"`
-	U64 uint64
+	U64 uint64 `json:"u64"`
-	F32 float32
+	F32 float32 `json:"f32"`
-	F64 float64
+	F64 float64 `json:"f64"`
-	V8 []int8
+	V8 []int8 `json:"v8"`
-	Vf64 []float64
+	Vf64 []float64 `json:"vf64"`
 }
 
 func (t *TypeAliasesT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/MyGame/Example/Vec3.go

@@ -7,12 +7,12 @@ import (
 )
 
 type Vec3T struct {
-	X float32
+	X float32 `json:"x"`
-	Y float32
+	Y float32 `json:"y"`
-	Z float32
+	Z float32 `json:"z"`
-	Test1 float64
+	Test1 float64 `json:"test1"`
-	Test2 Color
+	Test2 Color `json:"test2"`
-	Test3 *TestT
+	Test3 *TestT `json:"test3"`
 }
 
 func (t *Vec3T) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {

tests/go_test.go

@@ -17,8 +17,9 @@
 package main
 
 import (
-	mygame "MyGame"                     // refers to generated code
+	mygame "MyGame"          // refers to generated code
-	example "MyGame/Example"            // refers to generated code
+	example "MyGame/Example" // refers to generated code
+	"encoding/json"
 	optional_scalars "optional_scalars" // refers to generated code
 
 	"bytes"
@@ -68,6 +69,35 @@ func TestMain(m *testing.M) {
 	os.Exit(m.Run())
 }
 
+// TestTextParsing test if text parsing works with object API.
+func TestTextParsing(t *testing.T) {
+	expectedMonster := example.MonsterT{
+		Mana:                  42,
+		Name:                  "foo",
+		LongEnumNormalDefault: example.LongEnumLongTwo,
+	}
+
+	buf := new(bytes.Buffer)
+	if err := json.NewEncoder(buf).Encode(expectedMonster); err != nil {
+		t.Fatal(err)
+	}
+
+	var monster example.MonsterT
+	if err := json.NewDecoder(buf).Decode(&monster); err != nil {
+		t.Fatal(err)
+	}
+
+	if monster.Mana != expectedMonster.Mana {
+		t.Fatal("wrong mana:", monster.Mana)
+	}
+	if monster.Name != expectedMonster.Name {
+		t.Fatal("wrong name:", monster.Name)
+	}
+	if monster.LongEnumNormalDefault != expectedMonster.LongEnumNormalDefault {
+		t.Fatal("wrong enum:", monster.LongEnumNormalDefault)
+	}
+}
+
 // TestAll runs all checks, failing if any errors occur.
 func TestAll(t *testing.T) {
 	// Verify that the Go FlatBuffers runtime library generates the

tests/optional_scalars/ScalarStuff.go

@@ -7,42 +7,42 @@ import (
 )
 
 type ScalarStuffT struct {
-	JustI8 int8
+	JustI8 int8 `json:"just_i8"`
-	MaybeI8 *int8
+	MaybeI8 *int8 `json:"maybe_i8"`
-	DefaultI8 int8
+	DefaultI8 int8 `json:"default_i8"`
-	JustU8 byte
+	JustU8 byte `json:"just_u8"`
-	MaybeU8 *byte
+	MaybeU8 *byte `json:"maybe_u8"`
-	DefaultU8 byte
+	DefaultU8 byte `json:"default_u8"`
-	JustI16 int16
+	JustI16 int16 `json:"just_i16"`
-	MaybeI16 *int16
+	MaybeI16 *int16 `json:"maybe_i16"`
-	DefaultI16 int16
+	DefaultI16 int16 `json:"default_i16"`
-	JustU16 uint16
+	JustU16 uint16 `json:"just_u16"`
-	MaybeU16 *uint16
+	MaybeU16 *uint16 `json:"maybe_u16"`
-	DefaultU16 uint16
+	DefaultU16 uint16 `json:"default_u16"`
-	JustI32 int32
+	JustI32 int32 `json:"just_i32"`
-	MaybeI32 *int32
+	MaybeI32 *int32 `json:"maybe_i32"`
-	DefaultI32 int32
+	DefaultI32 int32 `json:"default_i32"`
-	JustU32 uint32
+	JustU32 uint32 `json:"just_u32"`
-	MaybeU32 *uint32
+	MaybeU32 *uint32 `json:"maybe_u32"`
-	DefaultU32 uint32
+	DefaultU32 uint32 `json:"default_u32"`
-	JustI64 int64
+	JustI64 int64 `json:"just_i64"`
-	MaybeI64 *int64
+	MaybeI64 *int64 `json:"maybe_i64"`
-	DefaultI64 int64
+	DefaultI64 int64 `json:"default_i64"`
-	JustU64 uint64
+	JustU64 uint64 `json:"just_u64"`
-	MaybeU64 *uint64
+	MaybeU64 *uint64 `json:"maybe_u64"`
-	DefaultU64 uint64
+	DefaultU64 uint64 `json:"default_u64"`
-	JustF32 float32
+	JustF32 float32 `json:"just_f32"`
-	MaybeF32 *float32
+	MaybeF32 *float32 `json:"maybe_f32"`
-	DefaultF32 float32
+	DefaultF32 float32 `json:"default_f32"`
-	JustF64 float64
+	JustF64 float64 `json:"just_f64"`
-	MaybeF64 *float64
+	MaybeF64 *float64 `json:"maybe_f64"`
-	DefaultF64 float64
+	DefaultF64 float64 `json:"default_f64"`
-	JustBool bool
+	JustBool bool `json:"just_bool"`
-	MaybeBool *bool
+	MaybeBool *bool `json:"maybe_bool"`
-	DefaultBool bool
+	DefaultBool bool `json:"default_bool"`
-	JustEnum OptionalByte
+	JustEnum OptionalByte `json:"just_enum"`
-	MaybeEnum *OptionalByte
+	MaybeEnum *OptionalByte `json:"maybe_enum"`
-	DefaultEnum OptionalByte
+	DefaultEnum OptionalByte `json:"default_enum"`
 }
 
 func (t *ScalarStuffT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {