Golang mime/multipart.CreateFormFile(), CreateFormField() and FormDataContentType() functions example

package mime/multipart

Golang mime/multipart.CreateFormFile(), CreateFormField() and FormDataContentType() functions usage example

 var url string
 var file string

 // Prepare a form that you will submit to that URL.
 var buff bytes.Buffer
 w := multipart.NewWriter(&buff)

 // Add your image file
 f, err := os.Open(file)
 if err != nil {
 return
 }
 fw, err := w.CreateFormFile("image", file)
 if err != nil {
 return
 }
 if _, err = io.Copy(fw, f); err != nil {
 return
 }
 // Add the other fields
 if fw, err = w.CreateFormField("key"); err != nil {
 return
 }
 if _, err = fw.Write([]byte("KEY")); err != nil {
 return
 }
 // Don't forget to close the multipart writer.
 // If you don't close it, your request will be missing the terminating boundary.
 w.Close()

 // Now that you have a form, you can submit it to your handler.
 req, err := http.NewRequest("POST", url, &buff)
 if err != nil {
 return
 }

 // Don't forget to set the content type, this will contain the boundary.
 req.Header.Set("Content-Type", w.FormDataContentType())

 // Submit the request
 client := &http.Client{}
 res, err := client.Do(req)
 if err != nil {
 return
 }

 // Check the response
 if res.StatusCode != http.StatusOK {
 err = fmt.Errorf("bad status: %s", res.Status)
 }
 return

References :

http://golang.org/pkg/mime/multipart/#Writer.CreateFormField

http://golang.org/pkg/mime/multipart/#Writer.FormDataContentType

http://stackoverflow.com/questions/20205796/golang-post-data-using-the-content-type-multipart-form-data