fix: parse multipart/form-data requests correctly

[c0per]

In current version, multipart form request will throw a parsing error.

This is because createMiddleware() treat req.body as the raw body and pass it to new Request().
But req.body is generated by express.json(), which only parse requests with content-type application/json and leave req.body undefined for other requests (like multipart form).

In the PR, req.body is prepared by express.raw({ type: '*/*' }). It will get a Buffer as the raw body for all the requests and pass it directly to new Request(). json, form, even other binary content types will be untouched by express and handled by user with Request API.

[c0per]

This will unfortunately be a breaking change. The must-need express.json() will be replaced by a express.raw({ type: '*/*' }).

I didn't think of a way to avoid a middleware. Express.js doesn't provide any way to access the raw request body but using express.raw()

[LeBenLeBen]

Just spent 2 hours trying to debug why calling req.formData() like in the docs was returning Unexpected end of multipart data 😅 Thank you for contributing.

Let me know if I can be of any help to get this merged and released.

[c0per]

I think a larger default size limit is a good idea.
I also changed the createServer() function to accept bodyParser options (optionally).

So for createServer() users, it's not a breaking change.
for createMiddleware(), it is breaking. They need to add app.use(express.raw()) manually.

@LeBenLeBen Please review these changes, wish we can merge this one. Thanks :)

[kettanaito]

What do you think if we bake in express.raw() into createMiddleware() itself?

Applying it to the entire server is too much anyway since people can attach handlers-based routes to an existing Express server.

In other words, having the raw body parser is a prerequisite of the middleware. So it must be defined there, next to the middleware.

[ernestostifano]

Hello guys, I got this error today: TypeError: Failed to parse body as FormData..

Is there anything I can do to help?