A cycle was detected in a LINQ expression exception

Question

I get the error :

A cycle was detected in a LINQ expression.

in ToList() while trying to do the following:

Answer 1

Of course there is a cycle. You are using entityIds in the Where Linq Extension method and it is the query being constructed itself. Instead of modifying the inputted IEnumerable, return a new query as follows:

private IEnumerable FilterIdsByClient(IEnumerable entityIds)
{
    var query =
        MyObjectContext.CreateObjectSet()
            .Where(x => x.ClientId == _clientId)
            .Where(x => entityIds.Contains(x.Id))
            .Select(x => x.Id);

    return query.ToList();
}