overhaul resolver validation

[helfer]

• don't enforce resolver presence at startup time, just print warnings or errors at runtime if a field without a custom resolve function is accessed and returns null.

[rdrey]

It would be great if resolvers and mocks can be mixed.

I've written a pretty large schema, and tested it with mocks. It would be great if I could now start to add resolvers and any broken fields keep returning mocked values. (With warnings / errors in the console or graphQL output.)

[helfer]

Can you elaborate a bit? What do you mean by broken fields returning mocked values? Are those fields with a resolver that returns undefined, or fields without a resolver at all? I think the latter would be useful, but the former sounds like a recipe for trouble.

[rdrey]

The latter. I actually just saw this commit e83226a and I'm wondering if I just need to update my graphql-tools.

[helfer]

That PR was actually just fixing another issue, which is to apply the resolvers before the mocks, to make sure the mocking of union types works (union types need the __resolveType function, which is not a resolver, but still has to be provided in the resolvers argument to apolloServer)

[helfer]

I think the easiest way to get this to work is for apolloServer to pass preserveResolvers = true to addMockFunctionsToSchema inside apolloServer.js

I'd be open to a PR in that direction, if you'd like to see that feature implemented.

[rdrey]

This works great for me, thanks. Would you like this to be a config option? Naming suggestions?

[rdrey]

I think mixing mocks and resolvers kind of implies that this is what I want to do, so I'm inclined to just leave this turned on by default.

[helfer]

I think rather than making it an option (and adding more arguments to the server), I would just turn it on by default like you suggested.

I just moved all the apolloServer code to apollo-server, so can you make your PR against the apollo-server repo? It would be a one-line change here, I think. Make sure to also add a test: https://github.com/apollostack/apollo-server/blob/2a4a41982d66d4a8502f2cff6a07018a9df8f1c4/src/apolloServer.js#L87

[helfer]

Closing this because we moved the server and the issue no longer exists here.