数据库计算- MVC 3和CodeFirst

Question

我正在尝试编写一个生成多个佣金单的方法。这是针对一所大学的，客户在导师的指导下注册参加一个名为"入学"的课程。通过这种方法，我试图将导师的客户每月的费用乘以他们的佣金百分比，因为导师可以从他们提供的课程中获得一定的佣金。下面是我的代码:

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 = enrolment.Tutor
                     };
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");
}

问题是TutorCommission条目是为每个单独的注册创建的，而不是为每个导师(每月)创建一个带有总佣金金额的条目。例如，Ashley有3个客户，因此有3个注册，目前正在为他创建3个TutorCommission条目。我想把报名人数加起来。此外，该金额没有乘以佣金百分比，因此只是作为全额注册月费节省下来。相关类为:

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; }
}

谢谢,艾米

Answer 1

您可以尝试将分组逻辑移到foreach循环之外，然后在分组列表上迭代。所以不用

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();
}

试

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();
foreach (var tutorCom in TutorComs)
{    
    db.TutorCommission.Add(tutorCom);
    db.SaveChanges();
}