[GraphQL] Custom mutations on collections / return type

[lukasluecke]

Similar to collection_query there should be collection_mutation for mutations that operate on multiple Resources, e.g. deleting multiple items in a single request by passing an array of IDs.

[lukasluecke]

Another possible solution might be to allow specifying the return type, similar to the way args works with custom types (#2824).

[alanpoulain]

I don't think the second solution is OK for this specific need (but it could be another enhancement) because the used resolver is only for queries, not mutations.
I'm not sure about this feature though. In GraphQL you can do it by using multiple mutations in one request.

[lukasluecke]

because the used resolver is only for queries, not mutations.

Could you explain what you mean?

And yes, you can send multiple mutations - but that would require you to dynamically build the mutations in the client side (which might involve a lot of work or be impossible depending on the libraries or client you use) - while having one mutation with an array argument will allow you to use the same mutation with different variables.

Also there will probably be other use cases for a custom return type (e.g. mutations that should just return a single value, like a number or boolean) - just as the args option is an "alternative" to Input Classes, the result option could be an "alternative" to Output Classes?

[brettins]

So the situation we are wanting to use this for is "claimBooks", where a user claims any books that have been associated with their phone number at a checkout, but they signed up as a user afterwards and gave their phone number.

In this case, we are updating multiple books to have their owner be the user, and would like to return that collection from the mutation. At the moment, this does not seem to be possible.