Dependency Injection of services for GraphQL

Question

I'm using NET5 webapi with HotChocolate package and am trying to inject a service. I've followed both standard and method based approach documented here however it doesn't work at all. All i get is the following message:

{
  "errors": [
    {
      "message": "Unexpected Execution Error",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "tests"
      ]
    }
  ],
  "data": {
    "tests": null
  }
}

My query:

query{
  tests {
    id
  }
}

My code currently reflects the method approach as documented.

In startup:

services
            .AddSingleton<ITestService, TestService>()
            .AddGraphQLServer()
            .AddDefaultTransactionScopeHandler()
            .AddQueryType<Queries>()
            .AddMutationType<Mutations>()
            .AddFiltering()
            .AddSorting()
            .AddProjections()
            .AddType<Test>();

The query setup:

        [UseProjection]
        [UseFiltering]
        [UseSorting]
        public IQueryable<Test> GetTests([Service] ITestService testService) => testService.GetTests();

My TestService:

private readonly IDbContextFactory<TestDbContext> contextFactory;

public TestService(IDbContextFactory<TestDbContext> contextFactory)
{
    this.contextFactory = contextFactory;
}

public IQueryable<Test> GetTests()
{
    using var context = contextFactory.CreateDbContext();

    return context.Test;
}

I'm sure I'm missing something simple to make this work.

Could you check in your debug output for the correct error? The "Unexpected execution error" is just a generic error for clients. In development, you should see a more concrete error in your debug output. — Tobias Tengler, Aug 04 '21 at 05:18
@TobiasTengler that is first thing i did, nothing in my Net debugger or on client side, its why i am struggling to figure out where the fault lies. — Aeseir, Aug 04 '21 at 05:26
Mhmm, that's really weird... Try including .ModifyOptions(o => o.IncludeExceptionDetails = true) after your services.AddGraphQLServer(). This should add the exception to the response. I typed this from memory on mobile, so maybe the option is called differently, jzst a heads up ^^ — Tobias Tengler, Aug 04 '21 at 06:10

score 0 · Accepted Answer · answered Aug 05 '21 at 09:32

0

Your DB Context is disposed. The using in GetTests is scoped for this method. On the end of this method the db context gets disposed and a Queryable is returned. Once the execution engine executes the Queryable, the exception is thrown

Checkout the EF Core integration of HotChocolate: https://chillicream.com/docs/hotchocolate/integrations/entity-framework

answered Aug 05 '21 at 09:32

Pascal Senn

1,712
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Yup, that was the simple dumb thing i missed. – Aeseir Aug 05 '21 at 11:14

Dependency Injection of services for GraphQL

1 Answers1