Support upload single or multiple files.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

context.go

@@ -8,6 +8,7 @@ import (
 	"errors"
 	"io"
 	"math"
+	"mime/multipart"
 	"net"
 	"net/http"
 	"net/url"
@@ -30,7 +31,10 @@ const (
 	MIMEMultipartPOSTForm = binding.MIMEMultipartPOSTForm
 )
 
-const abortIndex int8 = math.MaxInt8 / 2
+const (
+	defaultMemory      = 32 << 20 // 32 MB
+	abortIndex    int8 = math.MaxInt8 / 2
+)
 
 // 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.
@@ -291,7 +295,7 @@ func (c *Context) PostFormArray(key string) []string {
 func (c *Context) GetPostFormArray(key string) ([]string, bool) {
 	req := c.Request
 	req.ParseForm()
-	req.ParseMultipartForm(32 << 20) // 32 MB
+	req.ParseMultipartForm(defaultMemory)
 	if values := req.PostForm[key]; len(values) > 0 {
 		return values, true
 	}
@@ -303,6 +307,18 @@ func (c *Context) GetPostFormArray(key string) ([]string, bool) {
 	return []string{}, false
 }
 
+// FormFile returns the first file for the provided form key.
+func (c *Context) FormFile(name string) (*multipart.FileHeader, error) {
+	_, fh, err := c.Request.FormFile(name)
+	return fh, err
+}
+
+// MultipartForm is the parsed multipart form, including file uploads.
+func (c *Context) MultipartForm() (*multipart.Form, error) {
+	err := c.Request.ParseMultipartForm(defaultMemory)
+	return c.Request.MultipartForm, err
+}
+
 // Bind checks the Content-Type to select a binding engine automatically,
 // Depending the "Content-Type" header different bindings are used:
 // 		"application/json" --> JSON binding