Null object when paging nested objects

[aviiliix]

Product

Hot Chocolate

Version

15.0.3

Link to minimal reproduction

https://gist.github.com/aviiliix/12fa5c64de0bf119b5744eb28dc1c33a

Steps to reproduce

SDK & Packages:

• HotChocolate: 15.0.3
• .NET: 9
• Entity Framework: 9.0.2
• Automapper:

I use a combination of Implementation First to handle certain directives (database context, includes, and projection) and CodeFirst to handle descriptors (paging, filtering, projection directives).

The entities arrangement like this:

TestRuns has an ICollection of Executions; which are projected into TestRunReponse with deep handling of each of its objects nested to objects of type ...Response.

TestRunResponse:

public class TestRunResponse : BaseResponse
{
..
    public ICollection<ExecutionResponse?>? Executions { get; init; }
    public ICollection<LabelResponse?>? Labels { get; init; }
    public ICollection<RunParamResponse?>? RunParams { get; init; }
...
}

Startup:

services.AddGraphQLServer()
		        .RegisterDbContextFactory<ReadDatabaseContext>()	
		        .AddQueryType<GraphQueryType>()					
		        .AddType<TestRunResponseType>()				
		        .AddFiltering()									
		        .AddSorting()								
		        .AddProjections()									
		        .AddAuthorization();

GraphQueryHandler (The resultant objects for the query are mapped to TestRunResponse:

	public IQueryable<TestRunResponse> TestRuns([Service] ReadDatabaseContext databaseContext)
	{
		// Include necessary relationships to prevent lazy loading and optimize performance.
		return databaseContext.TestRuns
		                      .Include(t => t.TestRunExecutions)
		                      .Include(t => t.TestRunLabels)
		                      .Include(t => t.TestRunParams)
		                      .Include(t => t.Platform)
		                      .AsNoTracking()
		                      .ProjectTo<TestRunResponse>(Mapper.ConfigurationProvider);
	}

GraphQueryType:ObjectType (Support for paging the nested object ):

protected override void Configure(IObjectTypeDescriptor<GraphQueryHandler> descriptor)
{
		// Defines a field for fetching test runs, returning a TestRunResponseType.
		descriptor.Field(f => f.TestRuns(default!))
		          .Type<TestRunResponseType>()
		          .UseOffsetPaging(options: new PagingOptions
		                                    {
			                                    IncludeTotalCount = true,
			                                    MaxPageSize = 50,
			                                    AllowBackwardPagination = true
		                                    })
		          .UseProjection()
		          .UseFiltering()
		          .UseSorting();
}

TestRunResponseType : ObjectType:

{
	/// <summary>
	/// Configures the GraphQL TestRunResponse type, enabling filtering on the "Executions" field.
	/// </summary>
	/// <param name="descriptor">Descriptor used to define fields and configurations for the type.</param>
	protected override void Configure(IObjectTypeDescriptor<TestRunResponse> descriptor)
	{
		// Enables filtering on the "Executions" field using HotChocolate.
		descriptor.Field(t => t.Executions)
		          .UsePaging(options: new PagingOptions
		                              {
			                              IncludeTotalCount = true,
			                              MaxPageSize = 50,
			                              AllowBackwardPagination = true
		                              })
		          .UseFiltering()
		          .UseSorting();
	}
}

What is expected?

The nested objects returned over the query needs to be NotNull and Populated

What is actually happening?

Once I add support for paging nested objects in a query, the response object is always null, meanwhile In a normal query (without paging nested objects) the resultant objects are populated (right behaviour)

Relevant log output

Additional context

Query:

query { testRuns(take: 10, skip: 0) { items { id version originType platform { name } executions( first: 5 ) { edges { node { id } cursor } pageInfo { endCursor hasNextPage } } runParams { key value } } pageInfo { hasNextPage hasPreviousPage } totalCount } }

Response:

{ "data": { "testRuns": { "items": [ { "id": "13c451f3-680d-42dd-ab8b-2339f0c1fecc", "version": "584v10-584010", "originType": "CLOUD", "platform": { "name": "CV-ADR" }, "executions": null, // <---- Here lies the error "runParams": [ { "key": "ipCharles", "value": "-ipsp 0.0.0.0" }, { "key": "portAppium", "value": "-sp 4728" }, ....

[aviiliix]

Solved with the implementation of custom Resolver:

public IQueryable<ExecutionResponse> Executions(
	[Parent] TestRunResponse testRun,
	[Service] ReadDatabaseContext databaseContext)
{
	return databaseContext.TestRunExecutions
	                      .AsNoTracking()
	                      .Where(e => e.TestRunId.Equals(testRun.Id))
	                      .ProjectTo<ExecutionResponse>(Mapper.ConfigurationProvider);
}

// Configures the "Executions" field of the TestRunResponse type.
// Enables resolution using the specific resolver to obtain the executions.
descriptor.Field(t => t.Executions)
          .ResolveWith<TestRunResolver>(r => r.Executions(default!, default!))