Anonymous Type - Return method

[boukenka]

Hello,

Recently, I wanted to improve the field selection in Entity Framework Core when selecting data.
I wrote the following code:

public async Task<(long)> GetProviderIdAsync(long id)
{
  return await _zzContext.Test
               .Where(x => x.Id == id)
               .Select(x => new { x.ProviderId })
               .FirstOrDefaultAsync();
}

Of course, it doesn't work. 😄
I receive the following error message :

CS0029	Cannot implicitly convert type '<anonymous type: long ProviderId>' to '(long,?)'

Is it planned to implement in a future version of C#, an inference interpretation/logic to solve this issue ?
And not to manipulate it with a Dynamic type, an Object, another Anonymous type or Reflection?

For now, my solution is the following with a local variable:

public async Task<long> GetProviderIdAsync(long id)
{
    var result = await _zzContext.Test
                       .Where(x => x.Id == id)
                       .Select(x => new { x.ProviderId})
                       .FirstOrDefaultAsync();
    return result.ProviderId;
}

Thanks for any answer. 😄

[boukenka]

Why is it moved to discussion ?

[boukenka]

I wanted to ask that in the future, an anonymous object could be returned via a method in C# 10. So it needs an evolution of the C# langage.

[spydacarnage]

Needs is a strong word. You can return object already...

[boukenka]

Sorry. I am not a native speaker in English. I do not want to be rude or impolite. 😄 Yes object can be used. But from my point, this is not an elegant solution.

[spydacarnage]

How else would you want to specify an anonymous object as a return type? The point of an anonymous type/object is that it has no definition (apart from when it is explicitly created) so you can't return a "typed" anonymous type.

object is the only solution.

[boukenka]

Ok. Thanks for the answer.

[spydacarnage]

What are you actually trying to return in the Task? A long or a (long) ?
Regardless of that answer, neither is going to be able to be converted to from an anonymous object - why not just .Select(x => x.ProviderId) and return the long on its own?

[boukenka]

Thank you for the discussion. 😄

[Joe4evr]

I get a CS8143 error for the Select.

This is because ValueTuples are not supported in expression lambdas. See also: #2545.

[boukenka]

Thank you @Joe4evr. Seems there is no real progress in #2545.

[yaakov-h]

The expressions library is feature-locked. It is unlikely that expressions will ever represent new language constructs.

[boukenka]

Thank for the information @yaakov-h 😄