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package gin
import (
"bytes"
"encoding/json"
"encoding/xml"
"errors"
"fmt"
"github.com/gin-gonic/gin/binding"
"html/template"
"log"
"math"
"net/http"
"path"
"sync"
)
const (
AbortIndex = math.MaxInt8 / 2
MIMEJSON = "application/json"
MIMEHTML = "text/html"
MIMEXML = "application/xml"
MIMEXML2 = "text/xml"
MIMEPlain = "text/plain"
)
// Param is a single URL parameter, consisting of a key and a value.
type Param struct {
Key string
Value string
}
// Params is a Param-slice, as returned by the router.
// The slice is ordered, the first URL parameter is also the first slice value.
// It is therefore save to read values by the index.
type Params []Param
// ByName returns the value of the first Param which key matches the given name.
// If no matching Param is found, an empty string is returned.
func (ps Params) ByName(name string) string {
for i := range ps {
if ps[i].Key == name {
return ps[i].Value
}
}
return ""
}
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
// 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 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
}
// Represents the web framework, it wraps the blazing fast httprouter multiplexer and a list of global middlewares.
Engine struct {
*RouterGroup
HTMLTemplates *template.Template
cache sync.Pool
handlers404 []HandlerFunc
// Enables automatic redirection if the current route can't be matched but a
// handler for the path with (without) the trailing slash exists.
// For example if /foo/ is requested but a route only exists for /foo, the
// client is redirected to /foo with http status code 301 for GET requests
// and 307 for all other request methods.
RedirectTrailingSlash bool
// If enabled, the router tries to fix the current request path, if no
// handle is registered for it.
// First superfluous path elements like ../ or // are removed.
// Afterwards the router does a case-insensitive lookup of the cleaned path.
// If a handle can be found for this route, the router makes a redirection
// to the corrected path with status code 301 for GET requests and 307 for
// all other request methods.
// For example /FOO and /..//Foo could be redirected to /foo.
// RedirectTrailingSlash is independent of this option.
RedirectFixedPath bool
// router
trees map[string]*node
}
)
// Allows type H to be used with xml.Marshal
func (h H) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
start.Name = xml.Name{"", "map"}
if err := e.EncodeToken(start); err != nil {
return err
}
for key, value := range h {
elem := xml.StartElement{
xml.Name{"", key},
[]xml.Attr{},
}
if err := e.EncodeElement(value, elem); err != nil {
return err
}
}
if err := e.EncodeToken(xml.EndElement{start.Name}); err != nil {
return err
}
return nil
}
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()
}
// Returns a new blank Engine instance without any middleware attached.
// The most basic configuration
func New() *Engine {
engine := &Engine{}
engine.RouterGroup = &RouterGroup{nil, "/", nil, engine}
engine.cache.New = func() interface{} {
return &Context{Engine: engine, Writer: &responseWriter{}}
}
return engine
}
// 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) 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.Data(404, MIMEPlain, []byte("404 page not found"))
}
engine.cache.Put(c)
}
// ServeHTTP makes the router implement the http.Handler interface.
func (r *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if root := r.trees[req.Method]; root != nil {
path := req.URL.Path
if handlers, ps, tsr := root.getValue(path); handlers != nil {
c := r.createContext(w, req, ps, handlers)
c.Next()
r.cache.Put(c)
return
} else if req.Method != "CONNECT" && path != "/" {
code := 301 // Permanent redirect, request with GET method
if req.Method != "GET" {
// Temporary redirect, request with same method
// As of Go 1.3, Go does not support status code 308.
code = 307
}
if tsr && r.RedirectTrailingSlash {
if path[len(path)-1] == '/' {
req.URL.Path = path[:len(path)-1]
} else {
req.URL.Path = path + "/"
}
http.Redirect(w, req, req.URL.String(), code)
return
}
// Try to fix the request path
if r.RedirectFixedPath {
fixedPath, found := root.findCaseInsensitivePath(
CleanPath(path),
r.RedirectTrailingSlash,
)
if found {
req.URL.Path = string(fixedPath)
http.Redirect(w, req, req.URL.String(), code)
return
}
}
}
}
// Handle 404
r.handle404(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 Params, handlers []HandlerFunc) *Context {
c := engine.cache.Get().(*Context)
c.Writer.reset(w)
c.Req = req
c.Params = params
c.handlers = handlers
c.Keys = nil
c.index = -1
return c
}
// 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)
if p[0] != '/' {
panic("path must begin with '/'")
}
if group.engine.trees == nil {
group.engine.trees = make(map[string]*node)
}
root := group.engine.trees[method]
if root == nil {
root = new(node)
group.engine.trees[method] = root
}
root.addRoute(p, handlers)
}
// 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********/
/************************************/
func filterFlags(content string) string {
for i, a := range content {
if a == ' ' || a == ';' {
return content[:i]
}
}
return content
}
// This function 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
// else --> returns an error
// 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.
func (c *Context) Bind(obj interface{}) bool {
var b binding.Binding
ctype := filterFlags(c.Req.Header.Get("Content-Type"))
switch {
case c.Req.Method == "GET":
b = binding.Form
case ctype == MIMEJSON:
b = binding.JSON
case ctype == MIMEXML || ctype == MIMEXML2:
b = binding.XML
default:
c.Fail(400, errors.New("unknown content-type: "+ctype))
return false
}
return c.BindWith(obj, b)
}
func (c *Context) BindWith(obj interface{}, b binding.Binding) bool {
if err := b.Bind(c.Req, obj); err != nil {
c.Fail(400, err)
return false
}
return true
}
// 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", MIMEJSON)
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", MIMEXML)
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", MIMEHTML)
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, format string, values ...interface{}) {
c.Writer.Header().Set("Content-Type", MIMEPlain)
if code >= 0 {
c.Writer.WriteHeader(code)
}
c.Writer.Write([]byte(fmt.Sprintf(format, values...)))
}
// Writes some data into the body stream and updates the HTTP code.
func (c *Context) Data(code int, contentType string, data []byte) {
if len(contentType) > 0 {
c.Writer.Header().Set("Content-Type", contentType)
}
if code >= 0 {
c.Writer.WriteHeader(code)
}
c.Writer.Write(data)
}