ajk / specialist-server Goto Github PK

http://facebook.github.io/graphql/October2016/#sec-Type-Name-Introspection

Hi ajk,
thanks for your wonderful work on specialist-server, I love it :)
Defining the schema with spec really helps to eliminate otherwise redundant code.
Also I enjoyed reading the code of your implementation 👍

While defining a bit more complex schema, I stumbled over an bug in the introspection. Depending on the order in which I defined the resolvers in the executor creation, some types had been missing.
I stripped it down to this minimal example.

The bug is caused by returning coll when (contains? coll (:name v-type)) in the case that (:name v-type) is nil for multiple types, because v-type was recursively calculated from (:ofType v-t).

A trivial fix would be checking that we are not in a recursive v-type before returning coll without taking care of the depending types in the :else case.

- (contains? coll (:name v-type)) coll
+ (and (contains? coll (:name v-type)) (= v-type (type v))) coll

This however would cause an infinite loop when types circular depend on each other as in the specialist-server.batch-loader-test example.

Therefore I suggest another fix:
When we assoc the original v to the v-type, we would be able to know the already processed vs and than don't need the (contains? coll (:name v-type)) case any longer, but can use the default case with the modification that we filter already processed vs from the set.

http://facebook.github.io/graphql/October2016/#sec-Input-Objects

http://facebook.github.io/graphql/October2016/#sec-Language.Variables

http://facebook.github.io/graphql/October2016/#sec-Enums

In order to solve N+1 queries problem, some form of batch loading and caching is needed.

Inspiration:
https://code.facebook.com/posts/302060973291128/open-sourcing-haxl-a-library-for-haskell/
https://github.com/facebook/dataloader

http://facebook.github.io/graphql/October2016/#sec-Unions
http://facebook.github.io/graphql/October2016/#sec-Interfaces

http://facebook.github.io/graphql/October2016/#sec-Type-System.Directives