Merge branch 'negotiation' into develop

CHANGELOG.md

@@ -1,5 +1,10 @@
 #Changelog
 
+###Gin 0.5 (Aug 21, 2014)
+
+- [NEW] Content Negotiation
+
+
 ###Gin 0.4 (Aug 21, 2014)
 
 - [NEW] Development mode

context.go

@@ -67,6 +67,7 @@ type Context struct {
 	Engine    *Engine
 	handlers  []HandlerFunc
 	index     int8
+	accepted  []string
 }
 
 /************************************/
@@ -81,6 +82,7 @@ func (engine *Engine) createContext(w http.ResponseWriter, req *http.Request, pa
 	c.handlers = handlers
 	c.Keys = nil
 	c.index = -1
+	c.accepted = nil
 	c.Errors = c.Errors[0:0]
 	return c
 }
@@ -275,3 +277,64 @@ func (c *Context) Data(code int, contentType string, data []byte) {
 func (c *Context) File(filepath string) {
 	http.ServeFile(c.Writer, c.Request, filepath)
 }
+
+/************************************/
+/******** CONTENT NEGOTIATION *******/
+/************************************/
+
+type Negotiate struct {
+	Offered  []string
+	HTMLPath string
+	HTMLData interface{}
+	JSONData interface{}
+	XMLData  interface{}
+	Data     interface{}
+}
+
+func (c *Context) Negotiate(code int, config Negotiate) {
+	switch c.NegotiateFormat(config.Offered...) {
+	case MIMEJSON:
+		data := chooseData(config.JSONData, config.Data)
+		c.JSON(code, data)
+
+	case MIMEHTML:
+		data := chooseData(config.HTMLData, config.Data)
+		if len(config.HTMLPath) == 0 {
+			panic("negotiate config is wrong. html path is needed")
+		}
+		c.HTML(code, config.HTMLPath, data)
+
+	case MIMEXML:
+		data := chooseData(config.XMLData, config.Data)
+		c.XML(code, data)
+
+	default:
+		c.Fail(http.StatusNotAcceptable, errors.New("the accepted formats are not offered by the server"))
+	}
+}
+
+func (c *Context) NegotiateFormat(offered ...string) string {
+	if len(offered) == 0 {
+		panic("you must provide at least one offer")
+	}
+	if c.accepted == nil {
+		c.accepted = parseAccept(c.Request.Header.Get("Accept"))
+	}
+	if len(c.accepted) == 0 {
+		return offered[0]
+
+	} else {
+		for _, accepted := range c.accepted {
+			for _, offert := range offered {
+				if accepted == offert {
+					return offert
+				}
+			}
+		}
+		return ""
+	}
+}
+
+func (c *Context) SetAccepted(formats ...string) {
+	c.accepted = formats
+}

utils.go

@@ -8,6 +8,7 @@ import (
 	"encoding/xml"
 	"reflect"
 	"runtime"
+	"strings"
 )
 
 type H map[string]interface{}
@@ -45,6 +46,29 @@ func filterFlags(content string) string {
 	return content
 }
 
+func chooseData(custom, wildcard interface{}) interface{} {
+	if custom == nil {
+		if wildcard == nil {
+			panic("negotiation config is invalid")
+		}
+		return wildcard
+	}
+	return custom
+}
+
+func parseAccept(accept string) []string {
+	parts := strings.Split(accept, ",")
+	for i, part := range parts {
+		index := strings.IndexByte(part, ';')
+		if index >= 0 {
+			part = part[0:index]
+		}
+		part = strings.TrimSpace(part)
+		parts[i] = part
+	}
+	return parts
+}
+
 func funcName(f interface{}) string {
 	return runtime.FuncForPC(reflect.ValueOf(f).Pointer()).Name()
 }