Question

I’m trying to write a method that generates multiple invoices. This is for a college, where clients are enrolled with tutors in a class called Enrollments. With this method, I am trying to accumulate the monthly fee of the tutors clients multiplied by their commission percentages, as tutors earn a certain commission on the lessons they give. Here is my code for this:

public ActionResult CreateBulkCommissions()
{
    var month = DateTime.Now.ToString("MMMM");

    var enrolments = db.Enrollments.ToList();

    var newCommissions = from enrolment in enrolments
                         select new TutorCommission()
                         {
                             CommissionAmount = enrolment.MonthlyFee,
                             CommissionMonth = month,  // string constant 
                             CommissionStatus = "Unpaid",
                             Tutor = new Tutor { TutorNoID = enrolment.Tutor.TutorNoID, TutorCommissionPercentage = enrolment.Tutor.TutorCommissionPercentage }
                         };
    foreach (var newCommission in newCommissions)
    {
        List<TutorCommission> TutorComs = newCommissions.GroupBy(g => g.Tutor).Select(s => new TutorCommission
        {
            CommissionAmount = s.Sum(u => u.CommissionAmount) * s.Key.TutorCommissionPercentage,
            TutorNoID = s.Key.TutorNoID

        }).ToList();

        db.TutorCommission.Add(newCommission);
        db.SaveChanges();
    }

    return RedirectToAction("Index");
}

On SaveChanges, I receive the error that validation failed for one or more entities. When I view the values of newCommissions during debug, I notice that in TutorCommission, CommissionID and TutorNoID are 0, which might be the problem? How do I resolve this? Here’s a screenshot of that:

These are the relevant classes:

public class Enrollment
{
    [Key]
    [Display(Name = "Enrollment ID Number")]
    public long EnrollmentIDNumber { get; set; }
    [Display(Name = "Client ID Number")]
    public long ClientNumberID { get; set; }
    [Display(Name = "Tutor ID Number")]
    public long TutorNoID { get; set; }
    [Display(Name = "Course Name")]
    public string CourseName { get; set; }
    [Display(Name = "Lesson Time")]
    public string LessonTime { get; set; }
    [Display(Name = "Lesson Day")]
    public string LessonDay { get; set; }
    [Display(Name = "Lesson Location")]
    public string LessonLocation { get; set; }
    [Display(Name = "Lesson Type")]
    public string LessonType { get; set; }
    [Display(Name = "Lesson Level")]
    public string LessonLevel { get; set; }
    [Display(Name = "Monthly Fee")]
    public long MonthlyFee { get; set; }

    public virtual Client Client { get; set; }
    public virtual Tutor Tutor { get; set; }

}

public class TutorCommission
{
    [Key]
    [Display(Name = "Commission ID")]
    public long CommissionID { get; set; }
    [Display(Name = "Commission Month")]
    public string CommissionMonth {get; set;}
    [Display(Name = "Commission Amount")]
    public double CommissionAmount { get; set; }
    [Display(Name = "Commission Status")]
    public string CommissionStatus { get; set; }
    [Display(Name = "Tutor ID Number")]
    public long TutorNoID { get; set; }

    public virtual Tutor Tutor { get; set; }
    public virtual ICollection<CommissionPayments> CommissionPayments { get; set; }

}

public class Tutor
{
    [Key]
    [Display(Name = "Tutor ID Number")]
    public long TutorNoID { get; set; }
    [Required]
    [StringLength(50, ErrorMessage="First name must be less than 50 characters")]
    [Display(Name = "First Name")]
    public string TutorFirstName { get; set; }
    [StringLength(50, ErrorMessage = "Last name must be less than 50 characters")]
    [Display(Name = "Last Name")]
    public string TutorLastName { get; set; }
    [DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
    [Display(Name = "Birth Date")]
    public DateTime? TutorBirthDate { get; set; }
    [Display(Name = "Cellphone Number")]
    public string TutorCellphoneNumber { get; set; }
    [Display(Name = "Home Number")]
    public string TutorHomeNumber { get; set; }
    [RegularExpression("^[a-z0-9_\\+-]+(\\.[a-z0-9_\\+-]+)*@[a-z0-9-]+(\\.[a-z0-9-]+)*\\.([a-z]{2,4})$", ErrorMessage = "Not a valid email address")]
    [Display(Name = "Email Address")]
    public string TutorEmailAddress { get; set; }
    [Display(Name = "Street Address")]
    public string TutorStreetAddress { get; set; }
    [Display(Name = "Suburb")]
    public string TutorSuburb { get; set; }
    [Display(Name = "City")]
    public string TutorCity { get; set; }
    [Display(Name = "Postal Code")]
    public string TutorPostalCode { get; set; }
    [Display(Name="Full Name")]
    public string FullName
    {
        get
        {
            return TutorFirstName + " " + TutorLastName;
        }
    }
    [Display(Name="Commission Percentage")]
    [Required]
    public double TutorCommissionPercentage { get; set; }

    public virtual ICollection<Enrollment> Enrollments { get; set; }
    public virtual ICollection<TutorCommission> TutorCommissions { get; set; }

}

In EntityValidationErrors:

Count = 1
{System.Data.Entity.Validation.DbEntityValidationResult}

Thanks,
Amy

Answer 1

Try to change:

...
from enrolment in enrolments
                     select new TutorCommission()
                     {
                         CommissionAmount = enrolment.MonthlyFee,
                         CommissionMonth = month,  // string constant 
                         CommissionStatus = "Unpaid",
                         Tutor = new Tutor { TutorNoID = enrolment.Tutor.TutorNoID, TutorCommissionPercentage = enrolment.Tutor.TutorCommissionPercentage }
                     };

To:

from enrolment in enrolments
                     select new TutorCommission()
                     {
                         CommissionAmount = enrolment.MonthlyFee,
                         CommissionMonth = month,  // string constant 
                         CommissionStatus = "Unpaid",
                         Tutor = enrolment.Tutor
                     };

Because when you try to add the new newCommissions to the db EF tries to insert new tutors instead of making the association.