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 can use try/catch and write extenstion:

public static class QueryableExtensions
{
    public static TResult? MaxOrDefault(this IQueryable query, Expression> selector) where TResult : struct
    {
        try
        {
            return query.Max(selector);
        }
        catch
        {
            return null;
        }
    }
}

And use it as the following:

var version = ctx.Entries
            .Where(e => e.Competition.CompetitionId == storeCompetition.CompetitionId)
            .MaxOrDefault(e => e.Version);