Rebuild image/file widget with Uppy

[vnourdin]

Is your feature request related to a problem? Please describe.
File uploads management should be handled by a dedicated tool, to bring good features and more resiliency.
Uppy seems appropriate as it is made to be integrated and is well maintained.

Describe the solution you'd like
As described in #2243, using a dedicated library to manage uploads would solve a bunch of main issues about file or images upload.
I think Uppy is a better candidate than Filepond, as its code is already divided in modules, so we could easily use @uppy/core with Netlify CMS UI.

Additional context
You can find screenshots and documentation on the Uppy website.

[vnourdin]

@owenhoskins already gave a chance to Uppy in #1032, but this was discontinued, any idea why?

[erezrokah]

Hi @vnourdin it looks like it hit a wall because some limitations we had with uploading and deleting multiple files in a single commit.
I believe those limitations don't exist anymore as our backend implementations now support that.

It would be great to pick up that work and open a PR for it.

[mklueh]

Running into this "issue" as well. The feature would really be nice to have, as it is really time consuming to upload a bunch of images. Same goes for the selection for example, of the list widget. You need to add each image one by one

[patagoniapy]

Allowing the ability to add multiple images at once would really help supercharge the ability to build shippable products on Netlify CMS, as currently I am more reluctant to provide a client with a product that only allows them to add images one by one.

[erezrokah]

Hi @patagoniapy, agreed. It would be great to have this functionality if someone is willing to submit a PR for it.

[erezrokah]

Hi all 👋 I've made an attempt to add an external media library based on Uppy.

You can see the branch here and the deploy preview.
Please note I tested that branch only with a local backend.

Unfortunately it doesn't look like Uppy is a good candidate yet. It's an amazing file uploader, but lacking features required to be a complete media library.
For example, loading existing files is not officially supported. I was able to do it based on this issue, but it adds existing files as already uploaded ones instead of being an integral part of a media library.
Also, it seems nested directories are not supported.

See also transloadit/uppy#450.

I'm closing the issue, and will try to look at #2243 as well.

If you have suggestions on making Uppy suitable for the CMS, please comment on the issue and we can re-open it.