initial commit

vendor/github.com/ant0ine/go-json-rest/rest/response.go

@@ -0,0 +1,127 @@
+package rest
+
+import (
+	"bufio"
+	"encoding/json"
+	"net"
+	"net/http"
+)
+
+// A ResponseWriter interface dedicated to JSON HTTP response.
+// Note, the responseWriter object instantiated by the framework also implements many other interfaces
+// accessible by type assertion: http.ResponseWriter, http.Flusher, http.CloseNotifier, http.Hijacker.
+type ResponseWriter interface {
+
+	// Identical to the http.ResponseWriter interface
+	Header() http.Header
+
+	// Use EncodeJson to generate the payload, write the headers with http.StatusOK if
+	// they are not already written, then write the payload.
+	// The Content-Type header is set to "application/json", unless already specified.
+	WriteJson(v interface{}) error
+
+	// Encode the data structure to JSON, mainly used to wrap ResponseWriter in
+	// middlewares.
+	EncodeJson(v interface{}) ([]byte, error)
+
+	// Similar to the http.ResponseWriter interface, with additional JSON related
+	// headers set.
+	WriteHeader(int)
+}
+
+// This allows to customize the field name used in the error response payload.
+// It defaults to "Error" for compatibility reason, but can be changed before starting the server.
+// eg: rest.ErrorFieldName = "errorMessage"
+var ErrorFieldName = "Error"
+
+// Error produces an error response in JSON with the following structure, '{"Error":"My error message"}'
+// The standard plain text net/http Error helper can still be called like this:
+// http.Error(w, "error message", code)
+func Error(w ResponseWriter, error string, code int) {
+	w.WriteHeader(code)
+	err := w.WriteJson(map[string]string{ErrorFieldName: error})
+	if err != nil {
+		panic(err)
+	}
+}
+
+// NotFound produces a 404 response with the following JSON, '{"Error":"Resource not found"}'
+// The standard plain text net/http NotFound helper can still be called like this:
+// http.NotFound(w, r.Request)
+func NotFound(w ResponseWriter, r *Request) {
+	Error(w, "Resource not found", http.StatusNotFound)
+}
+
+// Private responseWriter intantiated by the resource handler.
+// It implements the following interfaces:
+// ResponseWriter
+// http.ResponseWriter
+// http.Flusher
+// http.CloseNotifier
+// http.Hijacker
+type responseWriter struct {
+	http.ResponseWriter
+	wroteHeader bool
+}
+
+func (w *responseWriter) WriteHeader(code int) {
+	if w.Header().Get("Content-Type") == "" {
+		// Per spec, UTF-8 is the default, and the charset parameter should not
+		// be necessary. But some clients (eg: Chrome) think otherwise.
+		// Since json.Marshal produces UTF-8, setting the charset parameter is a
+		// safe option.
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	}
+	w.ResponseWriter.WriteHeader(code)
+	w.wroteHeader = true
+}
+
+func (w *responseWriter) EncodeJson(v interface{}) ([]byte, error) {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return nil, err
+	}
+	return b, nil
+}
+
+// Encode the object in JSON and call Write.
+func (w *responseWriter) WriteJson(v interface{}) error {
+	b, err := w.EncodeJson(v)
+	if err != nil {
+		return err
+	}
+	_, err = w.Write(b)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Provided in order to implement the http.ResponseWriter interface.
+func (w *responseWriter) Write(b []byte) (int, error) {
+	if !w.wroteHeader {
+		w.WriteHeader(http.StatusOK)
+	}
+	return w.ResponseWriter.Write(b)
+}
+
+// Provided in order to implement the http.Flusher interface.
+func (w *responseWriter) Flush() {
+	if !w.wroteHeader {
+		w.WriteHeader(http.StatusOK)
+	}
+	flusher := w.ResponseWriter.(http.Flusher)
+	flusher.Flush()
+}
+
+// Provided in order to implement the http.CloseNotifier interface.
+func (w *responseWriter) CloseNotify() <-chan bool {
+	notifier := w.ResponseWriter.(http.CloseNotifier)
+	return notifier.CloseNotify()
+}
+
+// Provided in order to implement the http.Hijacker interface.
+func (w *responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	hijacker := w.ResponseWriter.(http.Hijacker)
+	return hijacker.Hijack()
+}