feat: support exception fields in BinaryConv t2j (#21)

* support exception field

* delete unused fields

* delete unused file

* optimize

* return json string

* add comments

* fix comment

conv/api.go

@@ -48,18 +48,18 @@ var (
 )
 
 type Options struct {
-	
+
 	// EnableValueMapping indicates if value mapping (api.js_conv...) should be enabled
 	EnableValueMapping bool
 	// EnableHttpMapping indicates if http mapping (api.query|api.header...) should be enabled
 	EnableHttpMapping bool
-	// EnableThriftBase indicates if thrift/base should be recoginized and mapping to/from context
+	// EnableThriftBase indicates if thrift/base should be recognized and mapping to/from context
 	EnableThriftBase bool
-	
+
 	// Int64AsString indicates if string value cane be read as **Int8/Int16/Int32/Int64/Float64**,
 	// or in response a **Int64** value can be written as string
 	String2Int64 bool
-	// NoBase64Binary indicates if base64 string shoud be Encode/Decode as []byte
+	// NoBase64Binary indicates if base64 string should be Encode/Decode as []byte
 	NoBase64Binary bool
 	// ByteAsUint8 indicates if byte should be conv as uint8 (default is int8), this only works for t2j now
 	ByteAsUint8 bool
@@ -73,7 +73,7 @@ type Options struct {
 	WriteRequireField bool
 	// DisallowUnknownField indicates if unknown fields should be skipped
 	DisallowUnknownField bool
-	
+
 	// ReadHttpValueFallback indicates if http-annotated fields should fallback to http body after reading from non-body parts (header,cookie...) failed
 	ReadHttpValueFallback bool
 	// WriteHttpValueFallback indicates if http-annotated fields should fallback to http body after writing to non-body parts (header,cookie...) failed
@@ -82,15 +82,17 @@ type Options struct {
 	// or root-level fields should be seeking on http-values when reading failed from current layer of json.
 	// this option is only used in j2t now.
 	TracebackRequredOrRootFields bool
-	// OmitHttpMappingErrors indicates to omit http-mapping failing errors. 
+	// OmitHttpMappingErrors indicates to omit http-mapping failing errors.
 	// If there are more-than-one HTTP annotations on the field, dynamicgo will try to mapping next annotation source (from left to right) until succeed.
 	OmitHttpMappingErrors bool
-	
+
 	// NoCopyString indicates if string-kind http values should be copied or just referenced (if possible)
 	NoCopyString bool
-	// UseNativeSkip indicates if use thrift.SkipNative() or thrift.SkipGo()
+	// UseNativeSkip indicates if using thrift.SkipNative() or thrift.SkipGo()
 	UseNativeSkip bool
-	
+
+	// ConvertException indicates that it returns error for thrift exception fields when doing BinaryConv t2j
+	ConvertException bool
 }
 
 var bufPool = sync.Pool{

conv/t2j/conv_test.go

@@ -282,6 +282,28 @@ func TestAGWBodyDynamic(t *testing.T) {
 	require.Equal(t, (`{"Int64":1,"Xjson":"{\"b\":1}"}`), string(out))
 }
 
+func TestException(t *testing.T) {
+	cv := NewBinaryConv(conv.Options{
+		ConvertException: true,
+	})
+	desc := thrift.FnWholeResponse(thrift.GetFnDescFromFile("testdata/idl/example3.thrift", "ExampleMethod", thrift.Options{}))
+
+	exp := example3.NewExampleServiceExampleMethodResult()
+	success := example3.NewExampleResp()
+	success.Status = 202
+	exception := example3.NewException()
+	exception.Code = 400
+	exception.Msg = "this is an exception"
+	exp.Success = success
+	exp.Err = exception
+	ctx := context.Background()
+	in := make([]byte, exp.BLength())
+	_ = exp.FastWriteNocopy(in, nil)
+	_, err := cv.Do(ctx, desc, in)
+	require.Error(t, err)
+	require.Equal(t, err.Error(), `{"code":400,"msg":"this is an exception"}`)
+}
+
 func TestInt2String(t *testing.T) {
 	cv := NewBinaryConv(conv.Options{
 		EnableValueMapping: true,
@@ -323,9 +345,9 @@ func TestHttpMappingFallback(t *testing.T) {
 		_ = exp.FastWriteNocopy(in, nil)
 		expJSON := `{}`
 		cv.SetOptions(conv.Options{
-			EnableHttpMapping:  true,
+			EnableHttpMapping:      true,
 			WriteHttpValueFallback: false,
-			OmitHttpMappingErrors: true,
+			OmitHttpMappingErrors:  true,
 		})
 		ctx := context.Background()
 		resp := http.NewHTTPResponse()
@@ -346,9 +368,9 @@ func TestHttpMappingFallback(t *testing.T) {
 		_ = exp.FastWriteNocopy(in, nil)
 		expJSON := `{"Msg":"hello"}`
 		cv.SetOptions(conv.Options{
-			EnableHttpMapping:  true,
+			EnableHttpMapping:      true,
 			WriteHttpValueFallback: true,
-			OmitHttpMappingErrors: true,
+			OmitHttpMappingErrors:  true,
 		})
 		ctx := context.Background()
 		resp := http.NewHTTPResponse()
@@ -510,9 +532,9 @@ func TestJSONString(t *testing.T) {
 	_ = exp.FastWriteNocopy(in, nil)
 
 	cv := NewBinaryConv(conv.Options{
-		EnableHttpMapping: true,
+		EnableHttpMapping:      true,
 		WriteHttpValueFallback: true,
-		OmitHttpMappingErrors: true,
+		OmitHttpMappingErrors:  true,
 	})
 	ctx := context.Background()
 	resp := http.NewHTTPResponse()
@@ -635,7 +657,6 @@ func TestOptionalDefaultValue(t *testing.T) {
 	})
 }
 
-
 func TestSimpleArgs(t *testing.T) {
 	cv := NewBinaryConv(conv.Options{})
 
@@ -658,4 +679,4 @@ func TestSimpleArgs(t *testing.T) {
 		require.NoError(t, err)
 		require.Equal(t, strconv.Itoa(math.MaxInt64), string(out))
 	})
-}
+}

conv/t2j/impl.go

@@ -18,6 +18,7 @@ package t2j
 
 import (
 	"context"
+	"errors"
 	"fmt"
 
 	"github.com/cloudwego/dynamicgo/conv"
@@ -83,6 +84,8 @@ func (self *BinaryConv) do(ctx context.Context, src []byte, desc *thrift.TypeDes
 	desc.Struct().Requires().CopyTo(r)
 	comma := false
 
+	existExceptionField := false
+
 	for {
 		_, typeId, id, e := p.ReadFieldBegin()
 		if e != nil {
@@ -139,6 +142,13 @@ func (self *BinaryConv) do(ctx context.Context, src []byte, desc *thrift.TypeDes
 		*out = json.EncodeString(*out, field.Alias())
 		*out = json.EncodeObjectColon(*out)
 
+		// handle a thrift exception field. the id of a thrift exception field is non-zero
+		if self.opts.ConvertException && id != 0 {
+			existExceptionField = true
+			// reset out to get only exception field data
+			*out = (*out)[:0]
+		}
+
 		if self.opts.EnableValueMapping && field.ValueMapping() != nil {
 			err = field.ValueMapping().Read(ctx, &p, field, out)
 			if err != nil {
@@ -150,6 +160,10 @@ func (self *BinaryConv) do(ctx context.Context, src []byte, desc *thrift.TypeDes
 				return unwrapError(fmt.Sprintf("converting field %s of STRUCT %s failed", field.Name(), desc.Type()), err)
 			}
 		}
+
+		if existExceptionField {
+			break
+		}
 	}
 
 	if err = self.handleUnsets(r, desc.Struct(), out, comma, ctx, resp); err != nil {
@@ -157,7 +171,11 @@ func (self *BinaryConv) do(ctx context.Context, src []byte, desc *thrift.TypeDes
 	}
 
 	thrift.FreeRequiresBitmap(r)
-	*out = json.EncodeObjectEnd(*out)
+	if existExceptionField && err == nil {
+		err = errors.New(string(*out))
+	} else {
+		*out = json.EncodeObjectEnd(*out)
+	}
 	return err
 }
 

thrift/test_util.go

@@ -43,6 +43,12 @@ func FnResponse(fn *FunctionDescriptor) *TypeDescriptor {
 	return fn.Response().Struct().FieldById(0).Type()
 }
 
+// FnWholeResponse get the normal response type
+func FnWholeResponse(fn *FunctionDescriptor) *TypeDescriptor {
+	// let-it-fail: it panic when something is nil
+	return fn.Response()
+}
+
 // FnRequest
 // We assume the request only have one argument and the only argument it the type we want.
 func FnRequest(fn *FunctionDescriptor) *TypeDescriptor {