Splitting source code in different files

context.go

@@ -0,0 +1,257 @@
+package gin
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"github.com/gin-gonic/gin/binding"
+	"github.com/gin-gonic/gin/render"
+	"github.com/julienschmidt/httprouter"
+	"log"
+	"net/http"
+)
+
+const (
+	ErrorTypeInternal = 1 << iota
+	ErrorTypeExternal = 1 << iota
+	ErrorTypeAll      = 0xffffffff
+)
+
+// Used internally to collect errors that occurred during an http request.
+type errorMsg struct {
+	Err  string      `json:"error"`
+	Type uint32      `json:"-"`
+	Meta interface{} `json:"meta"`
+}
+
+type errorMsgs []errorMsg
+
+func (a errorMsgs) ByType(typ uint32) errorMsgs {
+	if len(a) == 0 {
+		return a
+	}
+	result := make(errorMsgs, 0, len(a))
+	for _, msg := range a {
+		if msg.Type&typ > 0 {
+			result = append(result, msg)
+		}
+	}
+	return result
+}
+
+func (a errorMsgs) String() string {
+	if len(a) == 0 {
+		return ""
+	}
+	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)
+	}
+	return buffer.String()
+}
+
+// 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 {
+	Request  *http.Request
+	Writer   ResponseWriter
+	Keys     map[string]interface{}
+	Errors   errorMsgs
+	Params   httprouter.Params
+	Engine   *Engine
+	handlers []HandlerFunc
+	index    int8
+}
+
+/************************************/
+/********** ROUTES GROUPING *********/
+/************************************/
+
+func (engine *Engine) createContext(w http.ResponseWriter, req *http.Request, params httprouter.Params, handlers []HandlerFunc) *Context {
+	c := engine.cache.Get().(*Context)
+	c.Writer.reset(w)
+	c.Request = req
+	c.Params = params
+	c.handlers = handlers
+	c.Keys = nil
+	c.index = -1
+	return c
+}
+
+/************************************/
+/****** 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)
+}
+
+func (c *Context) ErrorTyped(err error, typ uint32, meta interface{}) {
+	c.Errors = append(c.Errors, errorMsg{
+		Err:  err.Error(),
+		Type: typ,
+		Meta: meta,
+	})
+}
+
+// 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.ErrorTyped(err, ErrorTypeExternal, 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********/
+/************************************/
+
+// 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.Request.Header.Get("Content-Type"))
+	switch {
+	case c.Request.Method == "GET" || ctype == MIMEPOSTForm:
+		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.Request, obj); err != nil {
+		c.Fail(400, err)
+		return false
+	}
+	return true
+}
+
+func (c *Context) Render(code int, render render.Render, obj ...interface{}) {
+	if err := render.Render(c.Writer, code, obj...); err != nil {
+		c.ErrorTyped(err, ErrorTypeInternal, obj)
+		c.Abort(500)
+	}
+}
+
+// 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.Render(code, render.JSON, obj)
+}
+
+// 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.Render(code, render.XML, obj)
+}
+
+// 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{}) {
+	c.Render(code, c.Engine.HTMLRender, name, obj)
+}
+
+// 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.Render(code, render.Plain, 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)
+}