【Go】gin.context
gin 1.7.2版本
// 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"
"fmt"
"io"
"io/ioutil"
"log"
"math"
"mime/multipart"
"net"
"net/http"
"net/url"
"os"
"strings"
"sync"
"time"
"github.com/gin-contrib/sse"
"github.com/gin-gonic/gin/binding"
"github.com/gin-gonic/gin/render"
)
// 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
MIMEYAML = binding.MIMEYAML
)
// BodyBytesKey indicates a default body bytes key.
const BodyBytesKey = "_gin-gonic/gin/bodybyteskey"
// abortIndex represents a typical value used in abort functions.
const abortIndex int8 = math.MaxInt8 >> 1
// 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
fullPath string
engine *Engine
params *Params
// This mutex protect Keys map
mu sync.RWMutex
// Keys is a key/value pair exclusively for the context of each request.
Keys map[string]interface{}
// Errors is a list of errors attached to all the handlers/middlewares who used this context.
Errors errorMsgs
// Accepted defines a list of manually accepted formats for content negotiation.
Accepted []string
// queryCache use url.ParseQuery cached the param query result from c.Request.URL.Query()
queryCache url.Values
// formCache use url.ParseQuery cached PostForm contains the parsed form data from POST, PATCH,
// or PUT body parameters.
formCache url.Values
// SameSite allows a server to define a cookie attribute making it impossible for
// the browser to send this cookie along with cross-site requests.
sameSite http.SameSite
// for customer
CustomContext CustomContext
}
type CustomContext struct {
Handle func(*Context) error
Desc string
Type string
Error error
StartTime time.Time
EndTime time.Time
}
func (c *CustomContext) HandlerName() string {
return nameOfFunction(c.Handle)
}
/************************************/
/********** CONTEXT CREATION ********/
/************************************/
func (c *Context) reset() {
c.Writer = &c.writermem
c.Params = c.Params[:0]
c.handlers = nil
c.index = -1
c.fullPath = ""
c.Keys = nil
c.Errors = c.Errors[:0]
c.Accepted = nil
c.queryCache = nil
c.formCache = nil
*c.params = (*c.params)[:0]
}
// Copy returns a copy of the current context that can be safely used outside the request's scope.
// This has to be used when the context has to be passed to a goroutine.
func (c *Context) Copy() *Context {
cp := Context{
writermem: c.writermem,
Request: c.Request,
Params: c.Params,
engine: c.engine,
}
cp.writermem.ResponseWriter = nil
cp.Writer = &cp.writermem
cp.index = abortIndex
cp.handlers = nil
cp.Keys = map[string]interface{}{}
for k, v := range c.Keys {
cp.Keys[k] = v
}
paramCopy := make([]Param, len(cp.Params))
copy(paramCopy, cp.Params)
cp.Params = paramCopy
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())
}
// HandlerNames returns a list of all registered handlers for this context in descending order,
// following the semantics of HandlerName()
func (c *Context) HandlerNames() []string {
hn := make([]string, 0, len(c.handlers))
for _, val := range c.handlers {
hn = append(hn, nameOfFunction(val))
}
return hn
}
// Handler returns the main handler.
func (c *Context) Handler() HandlerFunc {
return c.handlers.Last()
}
// FullPath returns a matched route full path. For not found routes
// returns an empty string.
// router.GET("/user/:id", func(c *gin.Context) {
// c.FullPath() == "/user/:id" // true
// })
func (c *Context) FullPath() string {
return c.fullPath
}
/************************************/
/*********** 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++
for c.index < int8(len(c.handlers)) {
c.handlers[c.index](c)
c.index++
}
}
// 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 authenticate a request could use: context.AbortWithStatus(401).
func (c *Context) AbortWithStatus(code int) {
c.Status(code)
c.Writer.WriteHeaderNow()
c.Abort()
}
// AbortWithStatusJSON calls `Abort()` and then `JSON` internally.
// This method stops the chain, writes the status code and return a JSON body.
// It also sets the Content-Type as "application/json".
func (c *Context) AbortWithStatusJSON(code int, jsonObj interface{}) {
c.Abort()
c.JSON(code, jsonObj)
}
// 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 *********/
/************************************/
// Error 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.
// Error will panic if err is nil.
func (c *Context) Error(err error) *Error {
if err == nil {
panic("err is nil")
}
parsedError, ok := err.(*Error)
if !ok {
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 exclusively for this context.
// It also lazy initializes c.Keys if it was not used previously.
func (c *Context) Set(key string, value interface{}) {
c.mu.Lock()
if c.Keys == nil {
c.Keys = make(map[string]interface{})
}
c.Keys[key] = value
c.mu.Unlock()
}
// 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) {
c.mu.RLock()
value, exists = c.Keys[key]
c.mu.RUnlock()
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
}
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