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package rest
import (
"bufio"
"encoding/json"
"net"
"net/http"
)
// JsonIndentMiddleware provides JSON encoding with indentation.
// It could be convenient to use it during development.
// It works by "subclassing" the responseWriter provided by the wrapping middleware,
// replacing the writer.EncodeJson and writer.WriteJson implementations,
// and making the parent implementations ignored.
type JsonIndentMiddleware struct {
// prefix string, as in json.MarshalIndent
Prefix string
// indentation string, as in json.MarshalIndent
Indent string
}
// MiddlewareFunc makes JsonIndentMiddleware implement the Middleware interface.
func (mw *JsonIndentMiddleware) MiddlewareFunc(handler HandlerFunc) HandlerFunc {
if mw.Indent == "" {
mw.Indent = " "
}
return func(w ResponseWriter, r *Request) {
writer := &jsonIndentResponseWriter{w, false, mw.Prefix, mw.Indent}
// call the wrapped handler
handler(writer, r)
}
}
// Private responseWriter intantiated by the middleware.
// It implements the following interfaces:
// ResponseWriter
// http.ResponseWriter
// http.Flusher
// http.CloseNotifier
// http.Hijacker
type jsonIndentResponseWriter struct {
ResponseWriter
wroteHeader bool
prefix string
indent string
}
// Replace the parent EncodeJson to provide indentation.
func (w *jsonIndentResponseWriter) EncodeJson(v interface{}) ([]byte, error) {
b, err := json.MarshalIndent(v, w.prefix, w.indent)
if err != nil {
return nil, err
}
return b, nil
}
// Make sure the local EncodeJson and local Write are called.
// Does not call the parent WriteJson.
func (w *jsonIndentResponseWriter) 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
}
// Call the parent WriteHeader.
func (w *jsonIndentResponseWriter) WriteHeader(code int) {
w.ResponseWriter.WriteHeader(code)
w.wroteHeader = true
}
// Make sure the local WriteHeader is called, and call the parent Flush.
// Provided in order to implement the http.Flusher interface.
func (w *jsonIndentResponseWriter) Flush() {
if !w.wroteHeader {
w.WriteHeader(http.StatusOK)
}
flusher := w.ResponseWriter.(http.Flusher)
flusher.Flush()
}
// Call the parent CloseNotify.
// Provided in order to implement the http.CloseNotifier interface.
func (w *jsonIndentResponseWriter) CloseNotify() <-chan bool {
notifier := w.ResponseWriter.(http.CloseNotifier)
return notifier.CloseNotify()
}
// Provided in order to implement the http.Hijacker interface.
func (w *jsonIndentResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
hijacker := w.ResponseWriter.(http.Hijacker)
return hijacker.Hijack()
}
// Make sure the local WriteHeader is called, and call the parent Write.
// Provided in order to implement the http.ResponseWriter interface.
func (w *jsonIndentResponseWriter) Write(b []byte) (int, error) {
if !w.wroteHeader {
w.WriteHeader(http.StatusOK)
}
writer := w.ResponseWriter.(http.ResponseWriter)
return writer.Write(b)
}
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