c# - EF Core 3 x.Contains() in expression where x is ICollection

Question

I've got the following data layer setup:

public class Repository : IRepository {

    private readonly MyDbContext _dbContext;

        public List<Meter> Search(Expression<Func<Meter,bool>> criteria)
            IQueryable<Meter> results = _dbContext.Meters;
            return results.Where(criteria).ToList();
        }
    }
}

... from a client class:

IRepository _repository;

public void ClientMethod () {

    ICollection<int> ids = new List<int>() {1, 2, 3);
    var results = _repository.Search(c=> ids.Contains(c.Id)); // This throws exception

}

This results in the exception:

expression Where(source: DbSet, predicate: (m) => (Unhandled parameter: __ids_0).Contains(m.Id))' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync()

But if I change the collection reference to IEnumerable or List, it works:

public void ClientMethod () {

    // This works
    List<int> ids = new List<int>() {1, 2, 3);
    var results = _repository.Search(c=> ids.Contains(c.Id)); 

    // This works
    IEnumerable<int> ids = new List<int>() {1, 2, 3);
    var results = _repository.Search(c=> ids.Contains(c.Id)); 
}

Why is it not working for ICollection, but it does for IEnumerable and List? Many of my client methods take an ICollection as a parameter.

I'm using EF Core 3.0 but I believe I had the same problem in 2.1, it just didn't throw as it evaluated it on the client instead.

Answer 1

This is a known bug fixed in 3.1. 3.0 is almost unusable due to all regressions after the query pipeline rewrite.

I recommend following the issue tracker on github for ef core.