Can't select properties after group by in linq query

Question

I have two tables, Organization and ApplicationUser. The relationship between them is One to Many. That means one Organization can have multiple Users. Now I need to write a query to show some organization properties along with the total users for each organization. I am trying to write the query. But after GroupBy function whenever I try to fetch the Property nothing comes. Here is the query:

var lists = await (from org in _dbContext.Organizations.AsNoTracking()
                   join dept in _dbContext.Departments.AsNoTracking() on org.Id equals dept.OrganizationId into orgDeptTemp
                   from orgDept in orgDeptTemp.DefaultIfEmpty()
                   join user in _dbContext.ApplicationUsers.AsNoTracking() on org.Id equals user.OrganizationId into orgUserTemp
                   from orgUser in orgUserTemp.DefaultIfEmpty()
                   group org by org.Id into orgGroupTemp
                   select new OrganizationDto
                   {
                       OrganizationId = orgGroupTemp.Key,
                       OrganizationName = orgGroupTemp.Key.......,
                       TotalUsers = How to get the total user
                   })
                   .ToListAsync();

Answer 1

In SQL the only available columns after a GROUP BY are the group key and aggregated columns. You need to add them into the group by line. So for example, group by org id and name

Answer 2

assuming your model is set up correctly use navigation properties

var query = from org in _dbContext.Organizations
            where org.Departments.Any(d => d.Whatever)
            select new OrganizationDto
            {
                OrganizationId = org.Id,
                OrganizationName = org.Name,
                TotalUsers = org.Users.Count(),
            };
var list = await query.AsNoTracking().ToListAsync();