Runtime: Suggestion: IAsyncQueryable

[lillo42]

I'm studying C# 8 and new we have a new interface call IAsyncEnumerable and I was think maybe it's a good ideia create a new interface call IAsyncQueryable to be possible using await foreach async with ORM like EF or NHibernarte:

IAsyncQueryable query = database.Where(...);

await foreach(var a in query) {
...
}

I was thinking IAsyncQueryable could be:

public interface IAsyncQueryable : IAsyncEnumerable
{
   Type ElementType { get; }
    Expression Expression { get; }
    IQueryProvider Provider { get; }
}


public interface IAsyncQueryable<T> : IAsyncQueryable, IAsyncEnumerable<T>
{

}

or

public interface IAsyncQueryable : IQueryable, IAsyncEnumerable
{

}


public interface IAsyncQueryable<T> : IQueryable<T>, IAsyncQueryable,  IAsyncEnumerable<T>
{

}

[Suchiman]

Since IQueryable is about composing a query rather than constructing an execution pipeline, it would probably make more sense to follow the current Approach (used by EF) of adding an extension like this

public static IAsyncEnumerable<TSource> AsAsyncEnumerable<TSource>(this IQueryable<TSource> source)

[quinmars]

The async enumerable implementation is developed in the dotnet/reactive repo. And there actually is already an IAsyncQueryable interface:

https://github.com/dotnet/reactive/blob/IxAsyncCSharp8/Ix.NET/Source/System.Linq.Async.Queryable/System/Linq/IAsyncQueryable.cs

[tarekgh]

cc @stephentoub

[stephentoub]

Without language support for awaits in expression trees, I don't think there's much that can or should be done here.
cc: @cston, @jaredpar

[jaredpar]

I agree. There is currently no plans to invest in our expression tree support at this time.

[tarekgh]

@jaredpar should we move this issue to your repo you may track it for the future if anything change?

[jaredpar]

Either way. This is one of those features that crosses our repositories so I'm fine with it being here or there.

[tarekgh]

Thanks @jaredpar I'll move it because corefx can support it if the it is decided from your side to support it.

[tarekgh]

Issue moved to dotnet/roslyn dotnet/runtime#27516 via ZenHub

[NimaFx]

Since IQueryable is about composing a query rather than constructing an execution pipeline, it would probably make more sense to follow the current Approach (used by EF) of adding an extension like this

public static IAsyncEnumerable<TSource> AsAsyncEnumerable<TSource>(this IQueryable<TSource> source)

IQueryable/LINQ supposes to abstract queries but at the same time, we have to add a reference to the entity framework? Where is the separation of concern part here? An application layer should be unaware of any underlying infrastructure! You promoting unportable code.

[Clockwork-Muse]

@NimaFx - No, I believe what they meant was "EF adds a method to turn IQueryable into IEnumerable, so we should probably add one to turn it into IAsyncEnumerable".