Entity Framework calling MAX on null on Records

Question

When calling Max() on an IQueryable and there are zero records I get the following exception.

The cast to value type \'Int32\' failed because the materialize

Answer 1

You could write a simple extension method like this, it returns the default value of type T if no records exist and is then apply Max to that or the query if records exist.

public static T MaxOrEmpty(this IQueryable query)
{
    return query.DefaultIfEmpty().Max();
}

and you could use it like this

maxId = context.Competition.Select(x=>x.CompetitionId).MaxOrEmpty();