Consider supporting more query operators inside EF.CompileQuery

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Stale
Tech stack
csharp
Domain
databases

Research direction

Start with the EF.CompileQuery and EF.CompileAsyncQuery entry points and compare the overloads that return IQueryable with those returning Task. Review how ToList, ToArray, and single-result operators are represented in the examples. Done means the supported operator scope and resulting compiled-query behavior are defined, with coverage for the intended overloads.

Written by the indexing model from the issue text.

Description

area-query blocked

For instance, ToList, or ToArray. I am not sure how the EF.CompileQuery/EF.CompileAsyncQuery is going to evolve with the adoption of the new IAsyncEnumerable<T>, but if it stays similar to what we have today, we could add logic to support what @cwoodruff described in https://twitter.com/cwoodruff/status/1090236542696779778:

private static readonly Func<ChinookContext, Task<List<Album>>> _queryGetAllAlbums =
    EF.CompileAsyncQuery((ChinookContext db) => db.Album.ToList());

This is matching an overload of CompileAsyncQuery that returns Task. These overloads are designed to work for methods that return a single element, e.g. a query that ends in First(). We didn't expect customers to use them to get a List.

AFAIK, if you want to get a list asynchronously from a compiled query, you have to create the compiled query calling an overload of CompileAsyncQuery that takes a lambda that returns an IQueryable, and then call ToListAsync() each time on the result of invoking the compiled query delegate, e.g.:

private static readonly Func<ChinookContext, Task<List<Album>>> _queryGetAllAlbums =
    EF.CompileAsyncQuery((ChinookContext db) => db.Album);
...
var results = await _queryGetAllAlbums(db).ToListAsync();
Dominant language
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