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 a error ocurred during a 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 http.ResponseWriter Keys map[string]interface{} Errors ErrorMsgs Params httprouter.Params handlers []HandlerFunc engine *Engine 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 wrappers the blazing fast httprouter multiplexer and a list of global middlewares. Engine struct { *RouterGroup handlers404 []HandlerFunc router *httprouter.Router HTMLTemplates *template.Template } ) func (a ErrorMsgs) String() string { var buffer bytes.Buffer for i, msg := range a { text := fmt.Sprintf("Error #%02d: %s \n Meta: %v\n\n", (i + 1), msg.Err, msg.Meta) buffer.WriteString(text) } 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.router = httprouter.New() engine.router.NotFound = engine.handle404 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) if engine.handlers404 == nil { http.NotFound(c.Writer, c.Req) } else { c.Writer.WriteHeader(404) } c.Next() } // 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) { http.ListenAndServe(addr, engine) } /************************************/ /********** ROUTES GROUPING *********/ /************************************/ func (group *RouterGroup) createContext(w http.ResponseWriter, req *http.Request, params httprouter.Params, handlers []HandlerFunc) *Context { return &Context{ Writer: w, Req: req, index: -1, engine: group.engine, Params: params, handlers: handlers, } } // Adds middlewares to the group, see example code in github. func (group *RouterGroup) Use(middlewares ...HandlerFunc) { group.Handlers = append(group.Handlers, middlewares...) } // Greates a new router group. You should create add all the routes that share that have common middlwares or 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) { group.createContext(w, req, params, handlers).Next() }) } // 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) } 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****/ /************************************/ // 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) { c.Writer.WriteHeader(code) c.index = AbortIndex } // Fail is the same than 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) } // Attachs an error to the current context. The error is pushed to a list of errors. // It's a gooc idea to call Error for each error ocurred 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 specefied 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 } // Returns the value for the given key. // It panics if the value doesn't exist. func (c *Context) Get(key string) interface{} { var ok bool var item interface{} if c.Keys != nil { item, ok = c.Keys[key] } else { item, ok = nil, false } if !ok || item == nil { log.Panicf("Key %s doesn't exist", key) } return item } /************************************/ /******** 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 a 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 a 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 his file name. // It also update 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) }