I have this query in Linq which returns some values:
public List<AttendanceDetail> GetCourseAttendanceForDate(int courseId, int calendarId)
{
using (var db = new HIQTrainingEntities())
{
var attendance = from ca in db.Calendars
join i in db.Inscriptions on ca.CourseId equals i.CourseId
join a in db.Attendances on new { s1 = i.Id, s2 = ca.Id } equals new { s1 = a.InscriptionId, s2 = a.CalendarId } into attendanceTable
from z in attendanceTable.DefaultIfEmpty()
where (ca.CourseId == courseId && ca.Id == calendarId)
orderby i.Person.Name
select new AttendanceDetail
{
StudentName = i.Person.Name,
CompanyName = i.Person.Company.Name,
InscriptionId = i.Id,
StudentId = i.PersonId,
CalendarId = ca.Id,
Date = ca.CalendarDate,
Id = z.Id,
Status = z.Status,
Observation = z.Observation,
UserCreated = z.UserCreated,
CreatedDate = z.CreatedDate,
UserUpdated = z.UserUpdated,
UpdateDate = z.UpdateDate
};
return attendance.ToList();
}
}
When I execute this query this is the error that comes:
An exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll but was not handled in user code
Additional information: The cast to value type 'System.Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.
Why isn't my DefaultIfEmpty working ?
