HotChocolate 13 - Unable to infer or resolve a schema type from the type reference `@CostDirective`

Yesterday I talked about measuring and monitoring the operational complexity of your GraphQL operations. I talked specifically about the custom HotChocolate cost directive as a way to assign a complexity to a field.

	type Query {
	books(take: Int = 10): [Book] @cost(complexity: 10)
	}
	type Book {
	title
	author: Author
	}
	type Author {
	name
	}
	query {
	books {
	title
	}
	}

view raw example.graphql hosted with ❤ by GitHub

However after upgrading an ASP.NET Core GraphQL api to HotChocolate 13, the GraphQL schema could no longer be loaded. Instead I got the following error message back:

HotChocolate.SchemaException: For more details look at the `Errors` property.
Unable to infer or resolve a schema type from the type reference `@CostDirective`. (IRD3.API.GraphQL.LandbouwerType) at HotChocolate.Configuration.TypeInitializer.DiscoverTypes()
at HotChocolate.Configuration.TypeInitializer.Initialize()
at HotChocolate.SchemaBuilder.Setup.InitializeTypes(SchemaBuilder builder, IDescriptorContext context, IReadOnlyList`1 types)
at HotChocolate.SchemaBuilder.Setup.Create(SchemaBuilder builder, LazySchema lazySchema, IDescriptorContext context)
at HotChocolate.SchemaBuilder.Create(IDescriptorContext context)
at HotChocolate.SchemaBuilder.HotChocolate.ISchemaBuilder.Create(IDescriptorContext context)
at HotChocolate.Execution.RequestExecutorResolver.CreateSchemaAsync(ConfigurationContext context, RequestExecutorSetup setup, RequestExecutorOptions executorOptions, IServiceProvider schemaServices, TypeModuleChangeMonitor typeModuleChangeMonitor, CancellationToken cancellationToken)
at HotChocolate.Execution.RequestExecutorResolver.CreateSchemaServicesAsync(ConfigurationContext context, RequestExecutorSetup setup, CancellationToken cancellationToken)
at HotChocolate.Execution.RequestExecutorResolver.GetRequestExecutorNoLockAsync(String schemaName, CancellationToken cancellationToken)
at HotChocolate.Execution.RequestExecutorResolver.GetRequestExecutorAsync(String schemaName, CancellationToken cancellationToken)
at HotChocolate.Execution.RequestExecutorProxy.GetRequestExecutorAsync(CancellationToken cancellationToken)
at HotChocolate.AspNetCore.HttpPostMiddlewareBase.HandleRequestAsync(HttpContext context)
at HotChocolate.AspNetCore.HttpPostMiddlewareBase.InvokeAsync(HttpContext context)

Based on the documentation, everything should work and the code that was working for HotChocolate 12 should also work for 13.

It cost me a lot of time to figure out a solution, but in the end (as always) it was quite simple. I updated the bootstrapping code to explicitly register the cost directive:

	services.AddGraphQLServer()
	.AddType<RegionType>()
	.AddType<CountryType>()
	//Explicitly add the @cost directive
	.AddDirectiveType<CostDirectiveType>();

view raw Program.cs hosted with ❤ by GitHub

Remark: I encountered the problem in HotChocolate 13.9.6. Maybe the issue is already fixed in a newer version when you read this post.(Fingers crossed)