Expression Lambda to order fields with null value

wish help you to fix your issue Here's the model I have. , The following will work.

 var notificationCount = db.Notifications
      .GroupBy(x => new { x.CommentID, x.ProjectID, x.BookID, x.NotificationTypeID })
      .Count();

wish helps you You rock! Thank you very much for your great help. Actually I have encountered "LINQ to Entities does not recognize the method 'System.String Format(System.String, System.Object, System.Object)' method, and this method cannot be translated into a store expression." error message after first applying your method, but by adding ".ToList()" to the third line I have succeeded. So, for informing those who might need this great functionality here is the last state of the method in my Controller:

private void PopulateMeetingsDropDownList(object selectedMeetings = null)
{
    var meetingsQuery = repository.Meetings.ToList()
        .Join(repository.Cities, m => m.MeetingCityId, c => c.CityID,
                (m, c) => new
                {
                    CityID = c.CityID,
                    DisplayValue = string.Format("{0} ({1:dd MMMM yyyy})", c.CityName, m.MeetingStartDate) 
                })
       .OrderBy(x => x.CityID).ToList();
    ViewData["MeetingId"] = new SelectList(meetingsQuery, "CityID", "DisplayValue", selectedMeetings); 
}

I hope this helps . You can extend your lambda expression or using c# 6 features:

// use c# 6.0 ?. operator
listData = db.db_table
             .OrderBy(x => x.db_table1?.column_name)
             .ToList();

// check value manually
listData = db.db_table
             .OrderBy(x => x.db_table1 != null ? x.db_table1.column_name : string.Empty)
             .ToList();

// filter null values before sorting
listData = db.db_table
             .Where(x => x.db_table1 != null)
             .OrderBy(x => x.db_table1.column_name)
             .ToList();

hope this fix your issue You need an all function which is only true if every element of an iterable is True. Otherwise every input to your filter was returning True.

list(filter(lambda d: all(d[field] == reference_row[field] for field in compare_fields), my_list))

[d for d in my_list if 
 all(d[field] == reference_row[field] for field in compare_fields)]