clarify GraphQL::Batch.batch documentation

[stevecrozz]

I want to use GraphQL::Batch to load arguments for running mutations and it's not clear to me from reading the documentation if it is safe for me to use GraphQL::Batch.batch wherever I feel the need in my application. The note in the documentation refers only to using this in unit tests.

Can you provide clarification on whether GraphQL::Batch.batch can be safely used outside the test environment?

[dylanahsmith]

The documentation is lacking in the project, it mostly just has overview documentation in the form of a README, but could use reference documentation.

Outside of a GraphQL context, GraphQL::Batch.batch is needed to set GraphQL::Batch::Executor.current which is used to group loads and to re-use existing load results. Inside of a GraphQL context, like in a mutation, this GraphQL::Batch::Executor.current has already been set, so GraphQL::Batch.batch isn't needed for this purpose and will simply not change GraphQL::Batch::Executor.current.

The other thing GraphQL::Batch.batch does is that it calls ::Promise.sync on the result of the block to force the promise to be loaded and return its result. If this is all you need GraphQL::Batch.batch for, then you could just use Promise.sync directly or even call sync directly on the result if it is always a promise.

[cheerfulstoic]

One thing that took me a little while to figure out: If you're calling for().load() multiple times in a block (or even setting GraphQL::Batch::Executor.current manually) in order to test that case, you should create all of your promises first and then start calling sync on them. When I call sync immediately on each to get the result it doesn't batch the perform calls