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Copy pathgin.go
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459 lines (403 loc) · 13.1 KB
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package gin
import (
"bytes"
"encoding/json"
"encoding/xml"
"errors"
"fmt"
"github.com/julienschmidt/httprouter"
"html/template"
"log"
"math"
"net/http"
"path"
)
const (
AbortIndex = math.MaxInt8 / 2
)
type (
HandlerFunc func(*Context)
H map[string]interface{}
// Used internally to collect errors that occurred during an http request.
ErrorMsg struct {
Err string `json:"error"`
Meta interface{} `json:"meta"`
}
ErrorMsgs []ErrorMsg
Config struct {
CacheSize int
Preallocated int
}
// 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.
Context struct {
Req *http.Request
Writer ResponseWriter
Keys map[string]interface{}
Errors ErrorMsgs
Params httprouter.Params
Engine *Engine
handlers []HandlerFunc
index int8
}
// Used internally to configure router, a RouterGroup is associated with a prefix
// and an array of handlers (middlewares)
RouterGroup struct {
Handlers []HandlerFunc
prefix string
parent *RouterGroup
engine *Engine
}
//
10BC8
Represents the web framework, it wraps the blazing fast httprouter multiplexer and a list of global middlewares.
Engine struct {
*RouterGroup
HTMLTemplates *template.Template
cache chan *Context
handlers404 []HandlerFunc
router *httprouter.Router
}
)
var (
DefaultConfig = Config{
CacheSize: 1024,
Preallocated: 512,
}
)
func (a ErrorMsgs) String() string {
var buffer bytes.Buffer
for i, msg := range a {
text := fmt.Sprintf("Error #%02d: %s \n Meta: %v\n", (i + 1), msg.Err, msg.Meta)
buffer.WriteString(text)
}
buffer.WriteString("\n")
return buffer.String()
}
func NewWithConfig(config Config) *Engine {
if config.CacheSize < 2 {
panic("CacheSize must be at least 2")
}
if config.Preallocated > config.CacheSize {
panic("Preallocated must be less or equal to CacheSize")
}
engine := &Engine{}
engine.RouterGroup = &RouterGroup{nil, "/", nil, engine}
engine.router = httprouter.New()
engine.router.NotFound = engine.handle404
engine.cache = make(chan *Context, config.CacheSize)
// Fill it with empty contexts
for i := 0; i < config.Preallocated; i++ {
engine.cache <- &Context{Engine: engine, Writer: &responseWriter{}}
}
return engine
}
// Returns a new blank Engine instance without any middleware attached.
// The most basic configuration
func New() *Engine {
return NewWithConfig(DefaultConfig)
}
// Returns a Engine instance with the Logger and Recovery already attached.
func Default() *Engine {
engine := New()
engine.Use(Recovery(), Logger())
return engine
}
func (engine *Engine) LoadHTMLTemplates(pattern string) {
engine.HTMLTemplates = template.Must(template.ParseGlob(pattern))
}
// Adds handlers for NotFound. It return a 404 code by default.
func (engine *Engine) NotFound404(handlers ...HandlerFunc) {
engine.handlers404 = handlers
}
func (engine *Engine) CacheStress() float32 {
return 1.0 - float32(len(engine.cache))/float32(cap(engine.cache))
}
func (engine *Engine) handle404(w http.ResponseWriter, req *http.Request) {
handlers := engine.combineHandlers(engine.handlers404)
c := engine.createContext(w, req, nil, handlers)
c.Writer.setStatus(404)
c.Next()
if !c.Writer.Written() {
c.String(404, "404 page not found")
}
engine.reuseContext(c)
}
// ServeFiles serves files from the given file system root.
// The path must end with "/*filepath", files are then served from the local
// path /defined/root/dir/*filepath.
// For example if root is "/etc" and *filepath is "passwd", the local file
// "/etc/passwd" would be served.
// Internally a http.FileServer is used, therefore http.NotFound is used instead
// of the Router's NotFound handler.
// To use the operating system's file system implementation,
// use http.Dir:
// router.ServeFiles("/src/*filepath", http.Dir("/var/www"))
func (engine *Engine) ServeFiles(path string, root http.FileSystem) {
engine.router.ServeFiles(path, root)
}
// ServeHTTP makes the router implement the http.Handler interface.
func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
engine.router.ServeHTTP(w, req)
}
func (engine *Engine) Run(addr string) {
if err := http.ListenAndServe(addr, engine); err != nil {
panic(err)
}
}
/************************************/
/********** ROUTES GROUPING *********/
/************************************/
func (engine *Engine) createContext(w http.ResponseWriter, req *http.Request, params httprouter.Params, handlers []HandlerFunc) *Context {
select {
case c := <-engine.cache:
c.Writer.reset(w)
c.Req = req
c.Params = params
c.handlers = handlers
c.Keys = nil
c.index = -1
return c
default:
return &Context{
Writer: &responseWriter{w, -1, false},
Req: req,
Params: params,
handlers: handlers,
index: -1,
Engine: engine,
}
}
}
func (engine *Engine) reuseContext(c *Context) {
select {
case engine.cache <- c:
default:
}
}
// Adds middlewares to the group, see example code in github.
func (group *RouterGroup) Use(middlewares ...HandlerFunc) {
group.Handlers = append(group.Handlers, middlewares...)
}
// Creates a new router group. You should add all the routes that have common middlwares or the same path prefix.
// For example, all the routes that use a common middlware for authorization could be grouped.
func (group *RouterGroup) Group(component string, handlers ...HandlerFunc) *RouterGroup {
prefix := path.Join(group.prefix, component)
return &RouterGroup{
Handlers: group.combineHandlers(handlers),
parent: group,
prefix: prefix,
engine: group.engine,
}
}
// Handle registers a new request handle and middlewares with the given path and method.
// The last handler should be the real handler, the other ones should be middlewares that can and should be shared among different routes.
// See the example code in github.
//
// For GET, POST, PUT, PATCH and DELETE requests the respective shortcut
// functions can be used.
//
// This function is intended for bulk loading and to allow the usage of less
// frequently used, non-standardized or custom methods (e.g. for internal
// communication with a proxy).
func (group *RouterGroup) Handle(method, p string, handlers []HandlerFunc) {
p = path.Join(group.prefix, p)
handlers = group.combineHandlers(handlers)
group.engine.router.Handle(method, p, func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {
c := group.engine.createContext(w, req, params, handlers)
c.Next()
group.engine.reuseContext(c)
})
}
// POST is a shortcut for router.Handle("POST", path, handle)
func (group *RouterGroup) POST(path string, handlers ...HandlerFunc) {
group.Handle("POST", path, handlers)
}
// GET is a shortcut for router.Handle("GET", path, handle)
func (group *RouterGroup) GET(path string, handlers ...HandlerFunc) {
group.Handle("GET", path, handlers)
}
// DELETE is a shortcut for router.Handle("DELETE", path, handle)
func (group *RouterGroup) DELETE(path string, handlers ...HandlerFunc) {
group.Handle("DELETE", path, handlers)
}
// PATCH is a shortcut for router.Handle("PATCH", path, handle)
func (group *RouterGroup) PATCH(path string, handlers ...HandlerFunc) {
group.Handle("PATCH", path, handlers)
}
// PUT is a shortcut for router.Handle("PUT", path, handle)
func (group *RouterGroup) PUT(path string, handlers ...HandlerFunc) {
group.Handle("PUT", path, handlers)
}
// OPTIONS is a shortcut for router.Handle("OPTIONS", path, handle)
func (group *RouterGroup) OPTIONS(path string, handlers ...HandlerFunc) {
group.Handle("OPTIONS", path, handlers)
}
// HEAD is a shortcut for router.Handle("HEAD", path, handle)
func (group *RouterGroup) HEAD(path string, handlers ...HandlerFunc) {
group.Handle("HEAD", path, handlers)
}
func (group *RouterGroup) combineHandlers(handlers []HandlerFunc) []HandlerFunc {
s := len(group.Handlers) + len(handlers)
h := make([]HandlerFunc, 0, s)
h = append(h, group.Handlers...)
h = append(h, handlers...)
return h
}
/************************************/
/****** FLOW AND ERROR MANAGEMENT****/
/************************************/
func (c *Context) Copy() *Context {
var cp Context = *c
cp.index = AbortIndex
cp.handlers = nil
return &cp
}
// Next should be used only in the middlewares.
// 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)
}
}
// Forces the system to do not continue calling the pending handlers.
// For example, the first handler checks if the request is authorized. If it's not, context.Abort(401) should be called.
// The rest of pending handlers would never be called for that request.
func (c *Context) Abort(code int) {
if code >= 0 {
c.Writer.WriteHeader(code)
}
c.index = AbortIndex
}
// Fail is the same as Abort plus an error message.
// Calling `context.Fail(500, err)` is equivalent to:
// ```
// context.Error("Operation aborted", err)
// context.Abort(500)
// ```
func (c *Context) Fail(code int, err error) {
c.Error(err, "Operation aborted")
c.Abort(code)
}
// 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, meta interface{}) {
c.Errors = append(c.Errors, ErrorMsg{
Err: err.Error(),
Meta: meta,
})
}
func (c *Context) LastError() error {
s := len(c.Errors)
if s > 0 {
return errors.New(c.Errors[s-1].Err)
} else {
return nil
}
}
/************************************/
/******** METADATA MANAGEMENT********/
/************************************/
// Sets a new pair key/value just for the specified context.
// It also lazy initializes the hashmap.
func (c *Context) Set(key string, item interface{}) {
if c.Keys == nil {
c.Keys = make(map[string]interface{})
}
c.Keys[key] = item
}
// Get returns the value for the given key or an error if the key does not exist.
func (c *Context) Get(key string) (interface{}, error) {
if c.Keys != nil {
item, ok := c.Keys[key]
if ok {
return item, nil
}
}
return nil, errors.New("Key does not exist.")
}
// MustGet returns the value for the given key or panics if the value doesn't exist.
func (c *Context) MustGet(key string) interface{} {
value, err := c.Get(key)
if err != nil || value == nil {
log.Panicf("Key %s doesn't exist", key)
}
return value
}
/************************************/
/******** ENCOGING MANAGEMENT********/
/************************************/
// Like ParseBody() but this method also writes a 400 error if the json is not valid.
func (c *Context) EnsureBody(item interface{}) bool {
if err := c.ParseBody(item); err != nil {
c.Fail(400, err)
return false
}
return true
}
// Parses the body content as a JSON input. It decodes the json payload into the struct specified as a pointer.
func (c *Context) ParseBody(item interface{}) error {
decoder := json.NewDecoder(c.Req.Body)
if err := decoder.Decode(&item); err == nil {
return Validate(c, item)
} else {
return err
}
}
// Serializes the given struct as JSON into the response body in a fast and efficient way.
// It also sets the Content-Type as "application/json".
func (c *Context) JSON(code int, obj interface{}) {
c.Writer.Header().Set("Content-Type", "application/json")
if code >= 0 {
c.Writer.WriteHeader(code)
}
encoder := json.NewEncoder(c.Writer)
if err := encoder.Encode(obj); err != nil {
c.Error(err, obj)
http.Error(c.Writer, err.Error(), 500)
}
}
// Serializes the given struct as XML into the response body in a fast and efficient way.
// It also sets the Content-Type as "application/xml".
func (c *Context) XML(code int, obj interface{}) {
c.Writer.Header().Set("Content-Type", "application/xml")
if code >= 0 {
c.Writer.WriteHeader(code)
}
encoder := xml.NewEncoder(c.Writer)
if err := encoder.Encode(obj); err != nil {
c.Error(err, obj)
http.Error(c.Writer, err.Error(), 500)
}
}
// 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, data interface{}) {
c.Writer.Header().Set("Content-Type", "text/html")
if code >= 0 {
c.Writer.WriteHeader(code)
}
if err := c.Engine.HTMLTemplates.ExecuteTemplate(c.Writer, name, data); err != nil {
c.Error(err, map[string]interface{}{
"name": name,
"data": data,
})
http.Error(c.Writer, err.Error(), 500)
}
}
// Writes the given string into the response body and sets the Content-Type to "text/plain".
func (c *Context) String(code int, msg string) {
if code >= 0 {
c.Writer.WriteHeader(code)
}
c.Writer.Header().Set("Content-Type", "text/plain")
c.Writer.Write([]byte(msg))
}
// Writes some data into the body stream and updates the HTTP code.
func (c *Context) Data(code int, data []byte) {
c.Writer.WriteHeader(code)
c.Writer.Write(data)
}