How to send multipart/form-data with Retrofit?

Question

I want to send an Article from and Android client to a REST server. Here is the Python model from the server:

class Article(models         


        

Answer 1

According to your curl request you are trying to create smth like this:

POST http://localhost:8000/api/v1/articles/ HTTP/1.1
User-Agent: curl/7.30.0
Host: localhost
Connection: Keep-Alive
Accept: application/json
Content-Length: 183431
Expect: 100-continue
Content-Type: multipart/form-data; boundary=----------------------------23473c7acabb

------------------------------23473c7acabb
Content-Disposition: form-data; name="author"

cURL
------------------------------23473c7acabb
Content-Disposition: form-data; name="photo"; filename="article-photo.png"
Content-Type: application/octet-stream

‰PNG



M\UUÕ+4qUUU¯°WUUU¿×ß¿þ Naa…k¿    IEND®B`‚
------------------------------23473c7acabb--

With retrofit adapter this request can be created in a next way:

@Multipart
@POST("/api/v1/articles/")
Observable uploadFile(@Part("author") TypedString authorString,
                                @Part("photo") TypedFile photoFile);

Usage:

TypedString author = new TypedString("cURL");
File photoFile = new File("/home/user/Desktop/article-photo.png");
TypedFile photoTypedFile = new TypedFile("image/*", photoFile);
retrofitAdapter.uploadFile(author, photoTypedFile)
               .subscribe(<...>);

Which creates similar output:

POST http://localhost:8000/api/v1/articles/ HTTP/1.1
Content-Type: multipart/form-data; boundary=32230279-83af-4480-abfc-88a880b21b19
Content-Length: 709
Host: localhost
Connection: Keep-Alive
Accept-Encoding: gzip
User-Agent: okhttp/2.3.0

--32230279-83af-4480-abfc-88a880b21b19
Content-Disposition: form-data; name="author"
Content-Type: text/plain; charset=UTF-8
Content-Length: 4
Content-Transfer-Encoding: binary

cUrl
--32230279-83af-4480-abfc-88a880b21b19
Content-Disposition: form-data; name="photo"; filename="article-photo.png"
Content-Type: image/*
Content-Length: 254
Content-Transfer-Encoding: binary



--32230279-83af-4480-abfc-88a880b21b19--

The key difference here is that you used POJO Article article as multipart param, which by default is converted by Converter into json. And your server expects plain string instead. With curl you are sending cURL, not {"author":"cURL"}.