Return new documents on add, handle offline add

[mattiaseyram]

Thanks for the awesome library @nandorojo!

Related github issue : #56

Changes

• return added docs on successful useCollection add call
• Synchronously set docs in useCollection add if offline

I noticed the add function provided by useCollection has Promise<void> as its return type. This could be improved by returning the added documents (including their new IDs) so that add can be used

I realize this could be an anti-pattern since we're unaware as to what actually happens on the server if we use a batch add. This could be improved by only returning the doc ids.

[nandorojo]

What if we made this behavior optional, with some sort of argument that lets you opt out of it? Something like silenceErrors? (Not sure about the name)

[cheunjm]

Any updates on your discussion here? Just want to point out that it might be useful to also add an "add" document function under 'hooks/static-mutations' (after this pr is merged)

[nandorojo]

Hey, there hasn't been much movement here. I commented here too.

For explanation on why there isn't currently a static add mutation, you can see my thoughts at #38 (comment). I've gone back and forth about it, the reason being that we can't update the SWR cache. So all we'd be doing is remaking the firestore add function. Maybe that's fine, not sure.

[nandorojo]

I thought more about this, and I think it's the right idea. I'll try to implement and test it when I have time in the next week.