Document how to configure custom `ExecutionStrategy`

[gli-chwy]

org.springframework.graphql.execution.ExceptionResolversExceptionHandler is package private, and it's not exposed as a Bean. Clearly it's designed that way.

I'm trying to extend graphql.execution.AsyncExecutionStrategy and override

@Override
protected CompletableFuture<ExecutionResult> completeValueForEnum(ExecutionContext executionContext, ExecutionStrategyParameters parameters, GraphQLEnumType enumType, Object result) 
{
}

to ignore unknown enum values in a class called IgnoreUnknownEnumValueExecutionStrategy. But the difficulty, without duplicating ExceptionResolversExceptionHandler, is I could not inject the ExceptionResolversExceptionHandler instance (which is hidden within the framework) into my IgnoreUnknownEnumValueExecutionStrategy bean.

Please advise if my use case and question is legitimate. Thanks.

[rstoyanchev]

I think this is the same case as #552. There we provided the static factory method DataFetcherExceptionResolver#createExceptionHandler to create the ExceptionResolversExceptionHandler instance.

We could try to take this a step further by facilitating the registration of execution strategies with the the DataFetcherExceptionHandler that we create. Something like this on GraphQlSource.Builder:

Builder configureExecutionStrategies(BiConsumer<GraphQL.Builder, DataFetcherExceptionHandler> configurer);

Or perhaps even a dedicated ExecutionStrategyFactory to create an ExecutionStrategy given a DataFetcherExceptionHandler. Although something like that could belong in GraphQL Java too.

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[gli-chwy]

Thank you @rstoyanchev for your response. I'll update our version to take advantage of DataFetcherExceptionResolver#createExceptionHandler since it is currently at 1.0.3.
You can decide on the further refinement you mentioned.

[rstoyanchev]

I'll update the title to reflect the actual goal to make it easier to configure a custom ExecutionStrategy. We need to consider whether to make a change here, or to request an enhancement in GraphQL Java's GraphQL.Builder. I'll leave this open for the time being.