Need help in POST multiple image file using retrofit?

Question

How to add multiple images/files on a same parameter along with other textual data using retrofit?

Single image is uploading perfectly using following interf         


        

Answer 1

Retrofit 2.0 + OkHttp 3

Interface declaration:

@POST("postpath")
Call upload(@Body MultipartBody filePart);

Creating MultiPartBody:

MultipartBody.Builder requestBodyBuilder = new MultipartBody.Builder()
                    .setType(MultipartBody.FORM);

then for each file(you can also add custom fields)

requestBodyBuilder.addFormDataPart("extraImage[]", "photo.jpg",
                            RequestBody.create(MediaType.parse("image/jpeg"), byteArrayOrFile));

and finally

api.upload(requestBodyBuilder.build());

P.S. you can add custom form fields (for example client.name) to the same form with

requestBodyBuilder.addFormDataPart("client[name]", null, RequestBody.create(MediaType.parse("text/plain"), name))

or

requestBodyBuilder.addFormDataPart("client[name]", name)) 

Retrofit 1.9:

You can use MultipartTypedOutput to post variable number of multi-part parameters.

In addition to François' answer, to post multiple images with the same / repeating field name(as an array) in retrofit you can use MultipartTypedOutput

Method signature:

@POST("/postpath")
SomeResponse upload(@Body MultipartTypedOutput output);

Usage:

MultipartTypedOutput multipartTypedOutput = new MultipartTypedOutput();
multipartTypedOutput.addPart("mainImage", new TypedFile("image/jpeg", mainImage));
multipartTypedOutput.addPart("extraImage[]", new TypedFile("image/jpeg", file1));
multipartTypedOutput.addPart("extraImage[]", new TypedFile("image/jpeg", file2));
upload(multipartTypedOutput);

Square brackets

Please note that some server side frameworks(Rails) typically require square brackets(i.e. extraImage[] instead of extraImage), others don't (Spring MVC).