How to perform projections on types other than IQueryable<T>?

[arjundnair-fingent]

Hi,

I read from the HotChocolate documentation that projections work on IQueryable<T> by default. I would like to know whether it is possible to perform projections on types other than IQueryable<T> like Enumerable<T> or List<T>. If it is possible, please do explain how to do it with an example. I've searched a lot on the internet for a solution, but not able to find anything related to this.

[PascalSenn]

In V13 we provide a IProjectionContext that you can use to project yourself. Otherwise there is [UseFirstOrDefault] or [UseSingleOrDefault].

[denis-trtnr]

Hi @arjundnair-fingent ,

I had the same problem because I needed the response as a List<>. This is how it worked for me while using the Entity Framework:

Here is my query:
[UseProjection] [UseFiltering] [UseSorting] public async Task<IEnumerable<TechData>> GetTechDataV2([Service] TechDataRepository techDataRepository, IResolverContext rcontext, string matNr, CancellationToken cancellationToken) => await techDataRepository.GetAllTechDataByMatNr(rcontext, matNr, cancellationToken);

And here my service
public async Task<IEnumerable<TechData>> GetAllTechDataByMatNr(IResolverContext resolverContext, string matNr, CancellationToken cancellationToken = default) { return _context.TechData.AsQueryable().Project(resolverContext).Where(t => t.MaterialId == matNr).ToList(); }