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257 lines
10 KiB
257 lines
10 KiB
package restful
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// Copyright 2013 Ernest Micklei. All rights reserved.
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// Use of this source code is governed by a license
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// that can be found in the LICENSE file.
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import (
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"bufio"
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"errors"
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"net"
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"net/http"
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)
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// DefaultResponseMimeType is DEPRECATED, use DefaultResponseContentType(mime)
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var DefaultResponseMimeType string
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//PrettyPrintResponses controls the indentation feature of XML and JSON serialization
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var PrettyPrintResponses = true
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// Response is a wrapper on the actual http ResponseWriter
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// It provides several convenience methods to prepare and write response content.
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type Response struct {
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http.ResponseWriter
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requestAccept string // mime-type what the Http Request says it wants to receive
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routeProduces []string // mime-types what the Route says it can produce
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statusCode int // HTTP status code that has been written explicitly (if zero then net/http has written 200)
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contentLength int // number of bytes written for the response body
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prettyPrint bool // controls the indentation feature of XML and JSON serialization. It is initialized using var PrettyPrintResponses.
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err error // err property is kept when WriteError is called
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hijacker http.Hijacker // if underlying ResponseWriter supports it
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}
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// NewResponse creates a new response based on a http ResponseWriter.
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func NewResponse(httpWriter http.ResponseWriter) *Response {
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hijacker, _ := httpWriter.(http.Hijacker)
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return &Response{ResponseWriter: httpWriter, routeProduces: []string{}, statusCode: http.StatusOK, prettyPrint: PrettyPrintResponses, hijacker: hijacker}
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}
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// DefaultResponseContentType set a default.
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// If Accept header matching fails, fall back to this type.
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// Valid values are restful.MIME_JSON and restful.MIME_XML
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// Example:
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// restful.DefaultResponseContentType(restful.MIME_JSON)
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func DefaultResponseContentType(mime string) {
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DefaultResponseMimeType = mime
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}
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// InternalServerError writes the StatusInternalServerError header.
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// DEPRECATED, use WriteErrorString(http.StatusInternalServerError,reason)
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func (r Response) InternalServerError() Response {
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r.WriteHeader(http.StatusInternalServerError)
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return r
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}
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// Hijack implements the http.Hijacker interface. This expands
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// the Response to fulfill http.Hijacker if the underlying
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// http.ResponseWriter supports it.
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func (r *Response) Hijack() (net.Conn, *bufio.ReadWriter, error) {
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if r.hijacker == nil {
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return nil, nil, errors.New("http.Hijacker not implemented by underlying http.ResponseWriter")
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}
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return r.hijacker.Hijack()
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}
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// PrettyPrint changes whether this response must produce pretty (line-by-line, indented) JSON or XML output.
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func (r *Response) PrettyPrint(bePretty bool) {
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r.prettyPrint = bePretty
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}
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// AddHeader is a shortcut for .Header().Add(header,value)
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func (r Response) AddHeader(header string, value string) Response {
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r.Header().Add(header, value)
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return r
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}
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// SetRequestAccepts tells the response what Mime-type(s) the HTTP request said it wants to accept. Exposed for testing.
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func (r *Response) SetRequestAccepts(mime string) {
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r.requestAccept = mime
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}
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// EntityWriter returns the registered EntityWriter that the entity (requested resource)
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// can write according to what the request wants (Accept) and what the Route can produce or what the restful defaults say.
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// If called before WriteEntity and WriteHeader then a false return value can be used to write a 406: Not Acceptable.
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func (r *Response) EntityWriter() (EntityReaderWriter, bool) {
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sorted := sortedMimes(r.requestAccept)
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for _, eachAccept := range sorted {
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for _, eachProduce := range r.routeProduces {
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if eachProduce == eachAccept.media {
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if w, ok := entityAccessRegistry.accessorAt(eachAccept.media); ok {
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return w, true
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}
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}
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}
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if eachAccept.media == "*/*" {
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for _, each := range r.routeProduces {
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if w, ok := entityAccessRegistry.accessorAt(each); ok {
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return w, true
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}
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}
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}
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}
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// if requestAccept is empty
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writer, ok := entityAccessRegistry.accessorAt(r.requestAccept)
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if !ok {
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// if not registered then fallback to the defaults (if set)
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if DefaultResponseMimeType == MIME_JSON {
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return entityAccessRegistry.accessorAt(MIME_JSON)
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}
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if DefaultResponseMimeType == MIME_XML {
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return entityAccessRegistry.accessorAt(MIME_XML)
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}
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// Fallback to whatever the route says it can produce.
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// https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
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for _, each := range r.routeProduces {
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if w, ok := entityAccessRegistry.accessorAt(each); ok {
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return w, true
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}
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}
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if trace {
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traceLogger.Printf("no registered EntityReaderWriter found for %s", r.requestAccept)
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}
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}
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return writer, ok
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}
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// WriteEntity calls WriteHeaderAndEntity with Http Status OK (200)
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func (r *Response) WriteEntity(value interface{}) error {
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return r.WriteHeaderAndEntity(http.StatusOK, value)
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}
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// WriteHeaderAndEntity marshals the value using the representation denoted by the Accept Header and the registered EntityWriters.
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// If no Accept header is specified (or */*) then respond with the Content-Type as specified by the first in the Route.Produces.
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// If an Accept header is specified then respond with the Content-Type as specified by the first in the Route.Produces that is matched with the Accept header.
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// If the value is nil then no response is send except for the Http status. You may want to call WriteHeader(http.StatusNotFound) instead.
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// If there is no writer available that can represent the value in the requested MIME type then Http Status NotAcceptable is written.
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// Current implementation ignores any q-parameters in the Accept Header.
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// Returns an error if the value could not be written on the response.
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func (r *Response) WriteHeaderAndEntity(status int, value interface{}) error {
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writer, ok := r.EntityWriter()
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if !ok {
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r.WriteHeader(http.StatusNotAcceptable)
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return nil
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}
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return writer.Write(r, status, value)
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}
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// WriteAsXml is a convenience method for writing a value in xml (requires Xml tags on the value)
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// It uses the standard encoding/xml package for marshalling the value ; not using a registered EntityReaderWriter.
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func (r *Response) WriteAsXml(value interface{}) error {
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return writeXML(r, http.StatusOK, MIME_XML, value)
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}
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// WriteHeaderAndXml is a convenience method for writing a status and value in xml (requires Xml tags on the value)
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// It uses the standard encoding/xml package for marshalling the value ; not using a registered EntityReaderWriter.
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func (r *Response) WriteHeaderAndXml(status int, value interface{}) error {
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return writeXML(r, status, MIME_XML, value)
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}
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// WriteAsJson is a convenience method for writing a value in json.
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// It uses the standard encoding/json package for marshalling the value ; not using a registered EntityReaderWriter.
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func (r *Response) WriteAsJson(value interface{}) error {
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return writeJSON(r, http.StatusOK, MIME_JSON, value)
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}
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// WriteJson is a convenience method for writing a value in Json with a given Content-Type.
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// It uses the standard encoding/json package for marshalling the value ; not using a registered EntityReaderWriter.
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func (r *Response) WriteJson(value interface{}, contentType string) error {
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return writeJSON(r, http.StatusOK, contentType, value)
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}
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// WriteHeaderAndJson is a convenience method for writing the status and a value in Json with a given Content-Type.
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// It uses the standard encoding/json package for marshalling the value ; not using a registered EntityReaderWriter.
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func (r *Response) WriteHeaderAndJson(status int, value interface{}, contentType string) error {
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return writeJSON(r, status, contentType, value)
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}
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// WriteError writes the http status and the error string on the response. err can be nil.
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// Return an error if writing was not successful.
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func (r *Response) WriteError(httpStatus int, err error) (writeErr error) {
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r.err = err
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if err == nil {
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writeErr = r.WriteErrorString(httpStatus, "")
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} else {
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writeErr = r.WriteErrorString(httpStatus, err.Error())
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}
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return writeErr
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}
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// WriteServiceError is a convenience method for a responding with a status and a ServiceError
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func (r *Response) WriteServiceError(httpStatus int, err ServiceError) error {
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r.err = err
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return r.WriteHeaderAndEntity(httpStatus, err)
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}
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// WriteErrorString is a convenience method for an error status with the actual error
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func (r *Response) WriteErrorString(httpStatus int, errorReason string) error {
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if r.err == nil {
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// if not called from WriteError
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r.err = errors.New(errorReason)
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}
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r.WriteHeader(httpStatus)
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if _, err := r.Write([]byte(errorReason)); err != nil {
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return err
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}
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return nil
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}
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// Flush implements http.Flusher interface, which sends any buffered data to the client.
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func (r *Response) Flush() {
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if f, ok := r.ResponseWriter.(http.Flusher); ok {
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f.Flush()
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} else if trace {
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traceLogger.Printf("ResponseWriter %v doesn't support Flush", r)
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}
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}
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// WriteHeader is overridden to remember the Status Code that has been written.
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// Changes to the Header of the response have no effect after this.
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func (r *Response) WriteHeader(httpStatus int) {
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r.statusCode = httpStatus
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r.ResponseWriter.WriteHeader(httpStatus)
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}
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// StatusCode returns the code that has been written using WriteHeader.
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func (r Response) StatusCode() int {
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if 0 == r.statusCode {
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// no status code has been written yet; assume OK
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return http.StatusOK
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}
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return r.statusCode
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}
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// Write writes the data to the connection as part of an HTTP reply.
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// Write is part of http.ResponseWriter interface.
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func (r *Response) Write(bytes []byte) (int, error) {
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written, err := r.ResponseWriter.Write(bytes)
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r.contentLength += written
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return written, err
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}
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// ContentLength returns the number of bytes written for the response content.
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// Note that this value is only correct if all data is written through the Response using its Write* methods.
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// Data written directly using the underlying http.ResponseWriter is not accounted for.
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func (r Response) ContentLength() int {
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return r.contentLength
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}
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// CloseNotify is part of http.CloseNotifier interface
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func (r Response) CloseNotify() <-chan bool {
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return r.ResponseWriter.(http.CloseNotifier).CloseNotify()
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}
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// Error returns the err created by WriteError
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func (r Response) Error() error {
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return r.err
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}
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