Feature request: streaming file uploads

[ddevault]

gqlgen's file upload support presently depends on http.Request.FormFile, which reads out the entire file into a temporary location, either RAM or on disk. This is more convenient to work with, but for large files, this can introduce a substantial overhead. Users sensitive to these constraints may prefer to use a streaming approach via http.Request.MultipartReader, which should be facilitated by gqlgen.

[freb]

I just ran into this. Before attempting to switch to GraphQL file uploads, I took great care to make sure all of my file uploads were stream processed to avoid using memory or disk space. This is most useful when you are not storing files on the same system as the application (e.g. forwarding them on to S3).

One issue is that the Upload object exposes an io.ReadSeeker (which is not supported by multipart.Part).

The larger issue is that multipart.Reader does not support seeking which would make it impossible to expose multiple files as Upload objects at the same time.

But I think for functions that support a single file upload, which would be obvious from the Map, it should be possible to expose the multipart.Part to the caller. You could add it as a reader to Upload.Part or something similar.

I'm not sure what it takes to actually get the changes approved, but it would be nice.