Multi-part form data

When sending larger amount of data to the server it’s common to use the multipart form data technique. Rest Assured provide methods called multiPart that allows you to specify a file, byte-array, input stream or text to upload. In its simplest form you can upload a file like this:

given().
        multiPart(new File("/path/to/file")).
when().
        post("/upload");

It will assume a control name called “file”. In HTML the control name is the attribute name of the input tag. To clarify let’s look at the following HTML form:

<form id="uploadForm" action="/upload" method="post" enctype="multipart/form-data">
        <input type="file" name="file" size="40">
        <input type=submit value="Upload!">
</form>

The control name in this case is the name of the input tag with name “file”. If you have a different control name then you need to specify it:

given().
        multiPart("controlName", new File("/path/to/file")).
when().
        post("/upload");

It’s also possible to supply multiple “multi-parts” entities in the same request:

byte[] someData = ..
given().
        multiPart("controlName1", new File("/path/to/file")).
        multiPart("controlName2", "my_file_name.txt", someData).
        multiPart("controlName3", someJavaObject, "application/json").
when().
        post("/upload");

For more advanced use cases you can make use of the MultiPartSpecBuilder. For example:

Greeting greeting = new Greeting();
greeting.setFirstName("John");
greeting.setLastName("Doe");

given().
        multiPart(new MultiPartSpecBuilder(greeting, ObjectMapperType.JACKSON_2)
                .fileName("greeting.json")
                .controlName("text")
                .mimeType("application/vnd.custom+json").build()).
when().
        post("/multipart/json").
then().
        statusCode(200);

You can specify, among other things, the default control name and filename using the MultiPartConfig. For example:

given().config(config().multiPartConfig(multiPartConfig().defaultControlName("something-else"))). ..

This will configure the default control name to be “something-else” instead of “file”.

For additional info refer to this blog post.