chore(*): expose several functions for external use (#409)

Co-authored-by: iawia002 <[email protected]>

errors/errors.go

@@ -111,6 +111,16 @@ func (e *err) Error() string {
 	return e.message.Message
 }
 
+// Reason returns the raw Reason string.
+func (e *err) Reason() string {
+	return string(e.message.Reason)
+}
+
+// Data returns the detailed error data.
+func (e *err) Data() map[string]string {
+	return e.message.Data
+}
+
 // factory is an error factory.
 type factory struct {
 	code   int

service/handler.go

@@ -166,7 +166,7 @@ func WriteError(ctx context.Context, producers []Producer, err interface{}) erro
 		return e
 	}
 	if len(producers) <= 0 {
-		return noProducerToWrite.Error(ats)
+		return NoProducerToWrite.Error(ats)
 	}
 	code := http.StatusInternalServerError
 	var msg interface{}
@@ -180,7 +180,7 @@ func WriteError(ctx context.Context, producers []Producer, err interface{}) erro
 		msg = err
 	}
 
-	producer := chooseProducer(ats, producers)
+	producer := ChooseProducer(ats, producers)
 	if producer == nil {
 		// Choose the first producer
 		producer = producers[0]
@@ -203,11 +203,11 @@ func WriteData(ctx context.Context, producers []Producer, code int, data interfa
 		return err
 	}
 	if len(producers) <= 0 {
-		return noProducerToWrite.Error(ats)
+		return NoProducerToWrite.Error(ats)
 	}
-	producer := chooseProducer(ats, producers)
+	producer := ChooseProducer(ats, producers)
 	if producer == nil {
-		return noProducerToWrite.Error(ats)
+		return NoProducerToWrite.Error(ats)
 	}
 	resp := httpCtx.ResponseWriter()
 	if resp.HeaderWritable() {
@@ -221,7 +221,8 @@ func WriteData(ctx context.Context, producers []Producer, code int, data interfa
 	return producer.Produce(resp, data)
 }
 
-func chooseProducer(acceptTypes []string, producers []Producer) Producer {
+// ChooseProducer chooses the right producer.
+func ChooseProducer(acceptTypes []string, producers []Producer) Producer {
 	if len(acceptTypes) <= 0 || len(producers) <= 0 {
 		return nil
 	}

service/utils.go

@@ -103,6 +103,8 @@ var (
 	NoContext = errors.InternalServerError.Build("Nirvana:Service:NoContext", "can't find http context, you should define `ctx context.Context` as the first parameter of your handler function")
 	// NoParameterGenerator represents no parameter generator error.
 	NoParameterGenerator = errors.InternalServerError.Build("Nirvana:Service:NoParameterGenerator", "no parameter generator for source ${source}")
+	// NoProducerToWrite represents no producer to write error.
+	NoProducerToWrite = errors.NotAcceptable.Build("Nirvana:Service:noProducerToWrite", "can't find producer for accept types ${types}")
 )
 
 var (
@@ -112,7 +114,6 @@ var (
 	invalidProducer        = errors.InternalServerError.Build("Nirvana:Service:invalidProducer", "${type} is invalid for producer")
 	noConnectionHijacker   = errors.InternalServerError.Build("Nirvana:Service:noConnectionHijacker", "underlying http.ResponseWriter does not implement http.Hijacker")
 	invalidMetaType        = errors.InternalServerError.Build("Nirvana:Service:invalidMetaType", "can't recognize meta for type ${type}")
-	noProducerToWrite      = errors.NotAcceptable.Build("Nirvana:Service:noProducerToWrite", "can't find producer for accept types ${types}")
 	invalidMethod          = errors.InternalServerError.Build("Nirvana:Service:invalidMethod", "http method ${method} is invalid")
 	invalidStatusCode      = errors.InternalServerError.Build("Nirvana:Service:invalidStatusCode", "http status code must be in [100,599]")
 	invalidBodyType        = errors.InternalServerError.Build("Nirvana:Service:invalidBodyType", "${type} is not a valid type for body")