How to inject formdata (or files in general)

[tombrouwer]

Hi, thanks for the hard work!

I try to test Fastify (with fastify multipart plugin). When I build the application and do a request (with insomnia/postman) it works fine. But I want to test the application with the inject method. But I can not figure it out how that will work. Can anyone help me with this?

Server:

const server = Fastify({ logger: { level: "debug" } });
server.register(multipart, { attachFieldsToBody: true });
server.post("/", { schema: {} }, async (request: FastifyRequest, reply: FastifyReply) => {
      const data = await request.file();
      console.log("data", data);
});

I tried a lot for the test so this is one of my attempts:
Test:

const fileData = fs.readFileSync(resolve(__dirname, `data/test.webp`));
const formData = new FormData();
formData.append("username", "nouser");
const blobblub = new Blob([fileData], { type: "image/webp" });
formData.append("filefield", blobblub);

const response = await server.inject({
    url: "/",
    method: "post",
    payload: formData,
    headers: { "Content-Type": 'multipart/form-data;boundary="boundary"' },
  });

If I not add ;boundary="boundary" to the header, it will give an error (Multipart: Boundary not found). But when I send it whith Insomnia it will accept the content-type header with the value multipart/form-data;.

Maybe someone with experience in testing with inject and files?

thanks in advance!

[leandroandrade]

Hi, form-auto-content can help you with it. Try something like this:

const formAutoContent = require('form-auto-content');

const form = formAutoContent({
      firstname: 'Foo',
      lastname: 'Bar',
      file: fs.createReadStream(path.join(__dirname, 'assets', 'fastify.pdf'))
  });

  const res = await fastify.inject({
      method: 'POST',
      url: '/upload-single',
      ...form
  });

[metcoder95]

The behavior is correct and intended, as by the spec RFC2046, the boundary property is mandatory. It is an arbitrary value added upon dispatch of a given request and should be attached at the end of the MIME of the multipart/form-data content type header.

It indicates the boundary or end of a Request's body. For instance, it is required to allow the server to understand where the stream's body ends.

Now, why it works in insomnia? It is because insomnia does this calculation and handling for you; meanwhile, light-my-request (the engine behind Fastify#inject) does not do this calculation nor handling of the boundary delimiter.

As @leandroandrade suggested, the usage of the given library handles all the logic required as insomnia does under-the-hood