Question

I have this simple method that returns a user:

User usr = ReliableExecution.RetryWithExpression<User, User>(u => u.FirstOrDefault(x => x.UserEmail == userEmail));

Now I need to create a similar method, but I need to return a list

List<Asset> lst = ReliableExecution.RetryWithExpression<Asset, List<Asset>>(u => u.SelectMany(x => x.EventId == eventId));

My problem is with the [SelectMany(x => x.EventId == eventId)] part that doesn’t compile and I can’t understand exactly how to use LINQ to get multiple results.
I have specified “SelectMany” just for an example, it can be whatever you find correct.

This is the signature of RetryWithExpression for reference:

   public static TValue RetryWithExpression<T, TValue>(Func<ObjectSet<T>, TValue> func, Int32 retryInfiniteLoopGuard = 0)
         where T : class

Answer 1

I think your expression should be rewritten as follows:

List<Asset> lst = ReliableExecution
    .RetryWithExpression<Asset, List<Asset>>(
        u => u.Where(x => x.EventId == eventId).ToList()
    );

In simple terms, SelectMany flattens a “list of lists of items A” into a “list of items B” using a functor that extracts a list of items B from each single item A; this is not what you want to do.