vendor/github.com/gin-gonic/gin/context.go
// Copyright 2014 Manu Martinez-Almeida. All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.
package gin
import (
"errors"
"io"
"math"
"net"
"net/http"
"net/url"
"strings"
"time"
"github.com/gin-gonic/gin/binding"
"github.com/gin-gonic/gin/render"
"github.com/manucorporat/sse"
"golang.org/x/net/context"
)
// Content-Type MIME of the most common data formats
const (
MIMEJSON = binding.MIMEJSON
MIMEHTML = binding.MIMEHTML
MIMEXML = binding.MIMEXML
MIMEXML2 = binding.MIMEXML2
MIMEPlain = binding.MIMEPlain
MIMEPOSTForm = binding.MIMEPOSTForm
MIMEMultipartPOSTForm = binding.MIMEMultipartPOSTForm
)
const abortIndex int8 = math.MaxInt8 / 2
// Context is the most important part of gin. It allows us to pass variables between middleware,
// manage the flow, validate the JSON of a request and render a JSON response for example.
type Context struct {
writermem responseWriter
Request *http.Request
Writer ResponseWriter
Params Params
handlers HandlersChain
index int8
engine *Engine
Keys map[string]interface{}
Errors errorMsgs
Accepted []string
}
var _ context.Context = &Context{}
/************************************/
/********** CONTEXT CREATION ********/
/************************************/
func (c *Context) reset() {
c.Writer = &c.writermem
c.Params = c.Params[0:0]
c.handlers = nil
c.index = -1
c.Keys = nil
c.Errors = c.Errors[0:0]
c.Accepted = nil
}
// Copy returns a copy of the current context that can be safely used outside the request's scope.
// This have to be used then the context has to be passed to a goroutine.
func (c *Context) Copy() *Context {
var cp = *c
cp.writermem.ResponseWriter = nil
cp.Writer = &cp.writermem
cp.index = abortIndex
cp.handlers = nil
return &cp
}
// HandlerName returns the main handler's name. For example if the handler is "handleGetUsers()", this
// function will return "main.handleGetUsers"
func (c *Context) HandlerName() string {
return nameOfFunction(c.handlers.Last())
}
/************************************/
/*********** FLOW CONTROL ***********/
/************************************/
// Next should be used only inside middleware.
// It executes the pending handlers in the chain inside the calling handler.
// See example in github.
func (c *Context) Next() {
c.index++
s := int8(len(c.handlers))
for ; c.index < s; c.index++ {
c.handlers[c.index](c)
}
}
// IsAborted returns true if the current context was aborted.
func (c *Context) IsAborted() bool {
return c.index >= abortIndex
}
// Abort prevents pending handlers from being called. Note that this will not stop the current handler.
// Let's say you have an authorization middleware that validates that the current request is authorized. If the
// authorization fails (ex: the password does not match), call Abort to ensure the remaining handlers
// for this request are not called.
func (c *Context) Abort() {
c.index = abortIndex
}
// AbortWithStatus calls `Abort()` and writes the headers with the specified status code.
// For example, a failed attempt to authentificate a request could use: context.AbortWithStatus(401).
func (c *Context) AbortWithStatus(code int) {
c.Status(code)
c.Writer.WriteHeaderNow()
c.Abort()
}
// AbortWithError calls `AbortWithStatus()` and `Error()` internally. This method stops the chain, writes the status code and
// pushes the specified error to `c.Errors`.
// See Context.Error() for more details.
func (c *Context) AbortWithError(code int, err error) *Error {
c.AbortWithStatus(code)
return c.Error(err)
}
/************************************/
/********* ERROR MANAGEMENT *********/
/************************************/
// Attaches an error to the current context. The error is pushed to a list of errors.
// It's a good idea to call Error for each error that occurred during the resolution of a request.
// 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.
func (c *Context) Error(err error) *Error {
var parsedError *Error
switch err.(type) {
case *Error:
parsedError = err.(*Error)
default:
parsedError = &Error{
Err: err,
Type: ErrorTypePrivate,
}
}
c.Errors = append(c.Errors, parsedError)
return parsedError
}
/************************************/
/******** METADATA MANAGEMENT********/
/************************************/
// Set is used to store a new key/value pair exclusivelly for this context.
// It also lazy initializes c.Keys if it was not used previously.
func (c *Context) Set(key string, value interface{}) {
if c.Keys == nil {
c.Keys = make(map[string]interface{})
}
c.Keys[key] = value
}
// Get returns the value for the given key, ie: (value, true).
// If the value does not exists it returns (nil, false)
func (c *Context) Get(key string) (value interface{}, exists bool) {
if c.Keys != nil {
value, exists = c.Keys[key]
}
return
}
// MustGet returns the value for the given key if it exists, otherwise it panics.
func (c *Context) MustGet(key string) interface{} {
if value, exists := c.Get(key); exists {
return value
}
panic("Key \"" + key + "\" does not exist")
}
/************************************/
/************ INPUT DATA ************/
/************************************/
// Param returns the value of the URL param.
// It is a shortcut for c.Params.ByName(key)
// router.GET("/user/:id", func(c *gin.Context) {
// // a GET request to /user/john
// id := c.Param("id") // id == "john"
// })
func (c *Context) Param(key string) string {
return c.Params.ByName(key)
}
// Query returns the keyed url query value if it exists,
// othewise it returns an empty string `("")`.
// It is shortcut for `c.Request.URL.Query().Get(key)`
// GET /path?id=1234&name=Manu&value=
// c.Query("id") == "1234"
// c.Query("name") == "Manu"
// c.Query("value") == ""
// c.Query("wtf") == ""
func (c *Context) Query(key string) string {
value, _ := c.GetQuery(key)
return value
}
// DefaultQuery returns the keyed url query value if it exists,
// othewise it returns the specified defaultValue string.
// See: Query() and GetQuery() for further information.
// GET /?name=Manu&lastname=
// c.DefaultQuery("name", "unknown") == "Manu"
// c.DefaultQuery("id", "none") == "none"
// c.DefaultQuery("lastname", "none") == ""
func (c *Context) DefaultQuery(key, defaultValue string) string {
if value, ok := c.GetQuery(key); ok {
return value
}
return defaultValue
}
// GetQuery is like Query(), it returns the keyed url query value
// if it exists `(value, true)` (even when the value is an empty string),
// othewise it returns `("", false)`.
// It is shortcut for `c.Request.URL.Query().Get(key)`
// GET /?name=Manu&lastname=
// ("Manu", true) == c.GetQuery("name")
// ("", false) == c.GetQuery("id")
// ("", true) == c.GetQuery("lastname")
func (c *Context) GetQuery(key string) (string, bool) {
req := c.Request
if values, ok := req.URL.Query()[key]; ok && len(values) > 0 {
return values[0], true
}
return "", false
}
// PostForm returns the specified key from a POST urlencoded form or multipart form
// when it exists, otherwise it returns an empty string `("")`.
func (c *Context) PostForm(key string) string {
value, _ := c.GetPostForm(key)
return value
}
// DefaultPostForm returns the specified key from a POST urlencoded form or multipart form
// when it exists, otherwise it returns the specified defaultValue string.
// See: PostForm() and GetPostForm() for further information.
func (c *Context) DefaultPostForm(key, defaultValue string) string {
if value, ok := c.GetPostForm(key); ok {
return value
}
return defaultValue
}
// GetPostForm is like PostForm(key). It returns the specified key from a POST urlencoded
// form or multipart form when it exists `(value, true)` (even when the value is an empty string),
// otherwise it returns ("", false).
// For example, during a PATCH request to update the user's email:
// email=mail@example.com --> ("mail@example.com", true) := GetPostForm("email") // set email to "mail@example.com"
// email= --> ("", true) := GetPostForm("email") // set email to ""
// --> ("", false) := GetPostForm("email") // do nothing with email
func (c *Context) GetPostForm(key string) (string, bool) {
req := c.Request
req.ParseMultipartForm(32 << 20) // 32 MB
if values := req.PostForm[key]; len(values) > 0 {
return values[0], true
}
if req.MultipartForm != nil && req.MultipartForm.File != nil {
if values := req.MultipartForm.Value[key]; len(values) > 0 {
return values[0], true
}
}
return "", false
}
// Bind checks the Content-Type to select a binding engine automatically,
// Depending the "Content-Type" header different bindings are used:
// "application/json" --> JSON binding
// "application/xml" --> XML binding
// otherwise --> returns an error
// It 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.
func (c *Context) Bind(obj interface{}) error {
b := binding.Default(c.Request.Method, c.ContentType())
return c.BindWith(obj, b)
}
// BindJSON is a shortcut for c.BindWith(obj, binding.JSON)
func (c *Context) BindJSON(obj interface{}) error {
return c.BindWith(obj, binding.JSON)
}
// BindWith binds the passed struct pointer using the specified binding engine.
// See the binding package.
func (c *Context) BindWith(obj interface{}, b binding.Binding) error {
if err := b.Bind(c.Request, obj); err != nil {
c.AbortWithError(400, err).SetType(ErrorTypeBind)
return err
}
return nil
}
// ClientIP implements a best effort algorithm to return the real client IP, it parses
// X-Real-IP and X-Forwarded-For in order to work properly with reverse-proxies such us: nginx or haproxy.
func (c *Context) ClientIP() string {
if c.engine.ForwardedByClientIP {
clientIP := strings.TrimSpace(c.requestHeader("X-Real-Ip"))
if len(clientIP) > 0 {
return clientIP
}
clientIP = c.requestHeader("X-Forwarded-For")
if index := strings.IndexByte(clientIP, ','); index >= 0 {
clientIP = clientIP[0:index]
}
clientIP = strings.TrimSpace(clientIP)
if len(clientIP) > 0 {
return clientIP
}
}
if ip, _, err := net.SplitHostPort(strings.TrimSpace(c.Request.RemoteAddr)); err == nil {
return ip
}
return ""
}
// ContentType returns the Content-Type header of the request.
func (c *Context) ContentType() string {
return filterFlags(c.requestHeader("Content-Type"))
}
func (c *Context) requestHeader(key string) string {
if values, _ := c.Request.Header[key]; len(values) > 0 {
return values[0]
}
return ""
}
/************************************/
/******** RESPONSE RENDERING ********/
/************************************/
func (c *Context) Status(code int) {
c.writermem.WriteHeader(code)
}
// Header is a intelligent shortcut for c.Writer.Header().Set(key, value)
// It writes a header in the response.
// If value == "", this method removes the header `c.Writer.Header().Del(key)`
func (c *Context) Header(key, value string) {
if len(value) == 0 {
c.Writer.Header().Del(key)
} else {
c.Writer.Header().Set(key, value)
}
}
func (c *Context) SetCookie(
name string,
value string,
maxAge int,
path string,
domain string,
secure bool,
httpOnly bool,
) {
if path == "" {
path = "/"
}
http.SetCookie(c.Writer, &http.Cookie{
Name: name,
Value: url.QueryEscape(value),
MaxAge: maxAge,
Path: path,
Domain: domain,
Secure: secure,
HttpOnly: httpOnly,
})
}
func (c *Context) Cookie(name string) (string, error) {
cookie, err := c.Request.Cookie(name)
if err != nil {
return "", err
}
val, _ := url.QueryUnescape(cookie.Value)
return val, nil
}
func (c *Context) Render(code int, r render.Render) {
c.Status(code)
if err := r.Render(c.Writer); err != nil {
panic(err)
}
}
// HTML renders the HTTP template specified by its file name.
// It also updates the HTTP code and sets the Content-Type as "text/html".
// See http://golang.org/doc/articles/wiki/
func (c *Context) HTML(code int, name string, obj interface{}) {
instance := c.engine.HTMLRender.Instance(name, obj)
c.Render(code, instance)
}
// IndentedJSON serializes the given struct as pretty JSON (indented + endlines) into the response body.
// It also sets the Content-Type as "application/json".
// WARNING: we recommend to use this only for development propuses since printing pretty JSON is
// more CPU and bandwidth consuming. Use Context.JSON() instead.
func (c *Context) IndentedJSON(code int, obj interface{}) {
c.Render(code, render.IndentedJSON{Data: obj})
}
// JSON serializes the given struct as JSON into the response body.
// It also sets the Content-Type as "application/json".
func (c *Context) JSON(code int, obj interface{}) {
c.Status(code)
if err := render.WriteJSON(c.Writer, obj); err != nil {
panic(err)
}
}
// XML serializes the given struct as XML into the response body.
// It also sets the Content-Type as "application/xml".
func (c *Context) XML(code int, obj interface{}) {
c.Render(code, render.XML{Data: obj})
}
// YAML serializes the given struct as YAML into the response body.
func (c *Context) YAML(code int, obj interface{}) {
c.Render(code, render.YAML{Data: obj})
}
// String writes the given string into the response body.
func (c *Context) String(code int, format string, values ...interface{}) {
c.Status(code)
render.WriteString(c.Writer, format, values)
}
// Redirect returns a HTTP redirect to the specific location.
func (c *Context) Redirect(code int, location string) {
c.Render(-1, render.Redirect{
Code: code,
Location: location,
Request: c.Request,
})
}
// Data writes some data into the body stream and updates the HTTP code.
func (c *Context) Data(code int, contentType string, data []byte) {
c.Render(code, render.Data{
ContentType: contentType,
Data: data,
})
}
// File writes the specified file into the body stream in a efficient way.
func (c *Context) File(filepath string) {
http.ServeFile(c.Writer, c.Request, filepath)
}
// SSEvent writes a Server-Sent Event into the body stream.
func (c *Context) SSEvent(name string, message interface{}) {
c.Render(-1, sse.Event{
Event: name,
Data: message,
})
}
func (c *Context) Stream(step func(w io.Writer) bool) {
w := c.Writer
clientGone := w.CloseNotify()
for {
select {
case <-clientGone:
return
default:
keepOpen := step(w)
w.Flush()
if !keepOpen {
return
}
}
}
}
/************************************/
/******** CONTENT NEGOTIATION *******/
/************************************/
type Negotiate struct {
Offered []string
HTMLName string
HTMLData interface{}
JSONData interface{}
XMLData interface{}
Data interface{}
}
func (c *Context) Negotiate(code int, config Negotiate) {
switch c.NegotiateFormat(config.Offered...) {
case binding.MIMEJSON:
data := chooseData(config.JSONData, config.Data)
c.JSON(code, data)
case binding.MIMEHTML:
data := chooseData(config.HTMLData, config.Data)
c.HTML(code, config.HTMLName, data)
case binding.MIMEXML:
data := chooseData(config.XMLData, config.Data)
c.XML(code, data)
default:
c.AbortWithError(http.StatusNotAcceptable, errors.New("the accepted formats are not offered by the server"))
}
}
func (c *Context) NegotiateFormat(offered ...string) string {
assert1(len(offered) > 0, "you must provide at least one offer")
if c.Accepted == nil {
c.Accepted = parseAccept(c.requestHeader("Accept"))
}
if len(c.Accepted) == 0 {
return offered[0]
}
for _, accepted := range c.Accepted {
for _, offert := range offered {
if accepted == offert {
return offert
}
}
}
return ""
}
func (c *Context) SetAccepted(formats ...string) {
c.Accepted = formats
}
/************************************/
/***** GOLANG.ORG/X/NET/CONTEXT *****/
/************************************/
func (c *Context) Deadline() (deadline time.Time, ok bool) {
return
}
func (c *Context) Done() <-chan struct{} {
return nil
}
func (c *Context) Err() error {
return nil
}
func (c *Context) Value(key interface{}) interface{} {
if key == 0 {
return c.Request
}
if keyAsString, ok := key.(string); ok {
val, _ := c.Get(keyAsString)
return val
}
return nil
}