Unable to Apply Linq Where Clause to Linked Entity in Entity Framework Core

Question

I have a EventEntity which has IEnumerable<Poc> PocEntity .

public class EventEntity
{
    public Guid Id { get; set; }
    public IEnumerable<PocEntity> Poc { get; set; }
}

I'm trying to filter EventEntity based on PocEntity . So I'm trying like this,

IQueryable<EventEntity> query = _context.Events.Where(x => x.Poc.Where(p => p.PocId.Equals(pocId)));

But I'm getting error and I'm not able to achieve this. Please assist on how to do this. I'm using EF Core.

I'm getting two errors, Error 1:

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'bool'

Error 2:

Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type

Answer 1

The error is because the argument to your first Where() clause is the wrong type. x => x.Poc.Where(p => p.PocId.Equals(pocId)) needs to evaluate to a bool. To do this, you can use Any() instead of Where():

IQueryable<EventEntity> query = _context.Events.Where(x => x.Poc.Any(p => p.PocId.Equals(pocId)));

Answer 2

The problem is with the first where condition:

.Where(x => x.Poc.Where(p => p.PocId.Equals(pocId)));

The where clause expects a bool expression while the only thing it gets is a collection: p.PocId.Equals(pocId)

Solution : Just add Any() to the end of the collection as the following:

.Where(x => x.Poc.Where(p => p.PocId.Equals(pocId)).Any())