278 lines
7.8 KiB
Go
278 lines
7.8 KiB
Go
// Copyright 2014 Manu Martinez-Almeida. All rights reserved.
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// Use of this source code is governed by a MIT style
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// license that can be found in the LICENSE file.
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package gin
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import (
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"bytes"
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"errors"
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"fmt"
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"github.com/gin-gonic/gin/binding"
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"github.com/gin-gonic/gin/render"
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"github.com/julienschmidt/httprouter"
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"log"
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"net/http"
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)
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const (
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ErrorTypeInternal = 1 << iota
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ErrorTypeExternal = 1 << iota
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ErrorTypeAll = 0xffffffff
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)
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// Used internally to collect errors that occurred during an http request.
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type errorMsg struct {
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Err string `json:"error"`
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Type uint32 `json:"-"`
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Meta interface{} `json:"meta"`
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}
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type errorMsgs []errorMsg
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func (a errorMsgs) ByType(typ uint32) errorMsgs {
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if len(a) == 0 {
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return a
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}
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result := make(errorMsgs, 0, len(a))
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for _, msg := range a {
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if msg.Type&typ > 0 {
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result = append(result, msg)
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}
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}
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return result
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}
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func (a errorMsgs) String() string {
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if len(a) == 0 {
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return ""
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}
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var buffer bytes.Buffer
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for i, msg := range a {
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text := fmt.Sprintf("Error #%02d: %s \n Meta: %v\n", (i + 1), msg.Err, msg.Meta)
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buffer.WriteString(text)
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}
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return buffer.String()
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}
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// Context is the most important part of gin. It allows us to pass variables between middleware,
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// manage the flow, validate the JSON of a request and render a JSON response for example.
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type Context struct {
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writermem responseWriter
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Request *http.Request
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Writer ResponseWriter
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Keys map[string]interface{}
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Errors errorMsgs
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Params httprouter.Params
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Engine *Engine
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handlers []HandlerFunc
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index int8
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}
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/************************************/
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/********** ROUTES GROUPING *********/
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/************************************/
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func (engine *Engine) createContext(w http.ResponseWriter, req *http.Request, params httprouter.Params, handlers []HandlerFunc) *Context {
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c := engine.cache.Get().(*Context)
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c.writermem.reset(w)
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c.Request = req
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c.Params = params
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c.handlers = handlers
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c.Keys = nil
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c.index = -1
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c.Errors = c.Errors[0:0]
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return c
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}
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/************************************/
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/****** FLOW AND ERROR MANAGEMENT****/
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/************************************/
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func (c *Context) Copy() *Context {
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var cp Context = *c
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cp.index = AbortIndex
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cp.handlers = nil
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return &cp
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}
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// Next should be used only in the middlewares.
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// It executes the pending handlers in the chain inside the calling handler.
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// See example in github.
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func (c *Context) Next() {
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c.index++
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s := int8(len(c.handlers))
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for ; c.index < s; c.index++ {
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c.handlers[c.index](c)
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}
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}
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// Forces the system to do not continue calling the pending handlers.
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// For example, the first handler checks if the request is authorized. If it's not, context.Abort(401) should be called.
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// The rest of pending handlers would never be called for that request.
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func (c *Context) Abort(code int) {
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if code >= 0 {
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c.Writer.WriteHeader(code)
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}
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c.index = AbortIndex
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}
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// Fail is the same as Abort plus an error message.
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// Calling `context.Fail(500, err)` is equivalent to:
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// ```
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// context.Error("Operation aborted", err)
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// context.Abort(500)
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// ```
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func (c *Context) Fail(code int, err error) {
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c.Error(err, "Operation aborted")
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c.Abort(code)
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}
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func (c *Context) ErrorTyped(err error, typ uint32, meta interface{}) {
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c.Errors = append(c.Errors, errorMsg{
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Err: err.Error(),
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Type: typ,
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Meta: meta,
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})
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}
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// Attaches an error to the current context. The error is pushed to a list of errors.
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// It's a good idea to call Error for each error that occurred during the resolution of a request.
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// A middleware can be used to collect all the errors and push them to a database together, print a log, or append it in the HTTP response.
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func (c *Context) Error(err error, meta interface{}) {
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c.ErrorTyped(err, ErrorTypeExternal, meta)
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}
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func (c *Context) LastError() error {
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s := len(c.Errors)
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if s > 0 {
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return errors.New(c.Errors[s-1].Err)
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} else {
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return nil
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}
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}
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/************************************/
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/******** METADATA MANAGEMENT********/
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/************************************/
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// Sets a new pair key/value just for the specified context.
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// It also lazy initializes the hashmap.
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func (c *Context) Set(key string, item interface{}) {
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if c.Keys == nil {
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c.Keys = make(map[string]interface{})
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}
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c.Keys[key] = item
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}
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// Get returns the value for the given key or an error if the key does not exist.
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func (c *Context) Get(key string) (interface{}, error) {
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if c.Keys != nil {
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item, ok := c.Keys[key]
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if ok {
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return item, nil
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}
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}
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return nil, errors.New("Key does not exist.")
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}
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// MustGet returns the value for the given key or panics if the value doesn't exist.
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func (c *Context) MustGet(key string) interface{} {
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value, err := c.Get(key)
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if err != nil || value == nil {
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log.Panicf("Key %s doesn't exist", key)
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}
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return value
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}
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/************************************/
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/******** ENCODING MANAGEMENT********/
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/************************************/
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// This function checks the Content-Type to select a binding engine automatically,
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// Depending the "Content-Type" header different bindings are used:
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// "application/json" --> JSON binding
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// "application/xml" --> XML binding
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// else --> returns an error
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// if Parses the request's body as JSON if Content-Type == "application/json" using JSON or XML as a JSON input. It decodes the json payload into the struct specified as a pointer.Like ParseBody() but this method also writes a 400 error if the json is not valid.
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func (c *Context) Bind(obj interface{}) bool {
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var b binding.Binding
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ctype := filterFlags(c.Request.Header.Get("Content-Type"))
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switch {
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case c.Request.Method == "GET" || ctype == MIMEPOSTForm:
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b = binding.Form
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case ctype == MIMEJSON:
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b = binding.JSON
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case ctype == MIMEXML || ctype == MIMEXML2:
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b = binding.XML
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default:
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c.Fail(400, errors.New("unknown content-type: "+ctype))
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return false
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}
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return c.BindWith(obj, b)
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}
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func (c *Context) BindWith(obj interface{}, b binding.Binding) bool {
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if err := b.Bind(c.Request, obj); err != nil {
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c.Fail(400, err)
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return false
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}
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return true
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}
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func (c *Context) Render(code int, render render.Render, obj ...interface{}) {
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if err := render.Render(c.Writer, code, obj...); err != nil {
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c.ErrorTyped(err, ErrorTypeInternal, obj)
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c.Abort(500)
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}
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}
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// Serializes the given struct as JSON into the response body in a fast and efficient way.
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// It also sets the Content-Type as "application/json".
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func (c *Context) JSON(code int, obj interface{}) {
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c.Render(code, render.JSON, obj)
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}
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// Serializes the given struct as XML into the response body in a fast and efficient way.
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// It also sets the Content-Type as "application/xml".
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func (c *Context) XML(code int, obj interface{}) {
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c.Render(code, render.XML, obj)
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}
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// Renders the HTTP template specified by its file name.
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// It also updates the HTTP code and sets the Content-Type as "text/html".
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// See http://golang.org/doc/articles/wiki/
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func (c *Context) HTML(code int, name string, obj interface{}) {
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c.Render(code, c.Engine.HTMLRender, name, obj)
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}
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// Writes the given string into the response body and sets the Content-Type to "text/plain".
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func (c *Context) String(code int, format string, values ...interface{}) {
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c.Render(code, render.Plain, format, values)
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}
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// Returns a HTTP redirect to the specific location.
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func (c *Context) Redirect(code int, location string) {
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if code >= 300 && code <= 308 {
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c.Render(code, render.Redirect, location)
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} else {
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panic(fmt.Sprintf("Cannot send a redirect with status code %d", code))
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}
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}
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// Writes some data into the body stream and updates the HTTP code.
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func (c *Context) Data(code int, contentType string, data []byte) {
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if len(contentType) > 0 {
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c.Writer.Header().Set("Content-Type", contentType)
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}
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if code >= 0 {
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c.Writer.WriteHeader(code)
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}
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c.Writer.Write(data)
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}
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// Writes the specified file into the body stream
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func (c *Context) File(filepath string) {
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http.ServeFile(c.Writer, c.Request, filepath)
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}
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