无法将方法组'ToList'转换为非委托类型

Question

我正在尝试编写一个生成多个发票的方法。这是为一所大学而做的，客户在名为Enrollments的课程中与导师注册。通过这个方法，我试图累积导师客户的月费用乘以他们的佣金百分比，因为导师按照他们所给的课程收取一定的佣金。以下是我的代码：

    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 = 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");
    }

在ToList行上，我收到了一个错误，它无法将方法组ToList转换为非委托类型。以下是我的相关模型类：

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; }

}

感谢您的来信，Amy。

- Amy

Answer 1

你应该使用 () 调用 ToList 方法，而不是 ToList。

- Alexei Levenkov

---

啊！总是有些简单的东西，谢谢。不过现在我又遇到了一个新错误，即一个或多个实体的验证失败。请参见“EntityValidationErrors”属性以获取更多详细信息。我在哪里可以找到EntityValidationErrors？ - Amy

实体验证错误出现在异常中。在此下载我的源代码，了解一种处理它们的方法。 http://completedevelopment.blogspot.com/2011/10/codecamp-nyc-entity-framework-mvc-code.html - Adam Tuliper

谢谢。像这样的异常通常会有什么问题？ - Amy

Answer 2

ToList是一个方法而不是属性。应该写成ToList()。

- MishaU

Answer 3

你是指：

    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();

- Mike Christensen

---

请注意TutorCommission构造函数后面的括号。 - Mike Christensen

在TutorCommission构造函数后面不需要加()。 - Christopher Currens

嗯，真的吗？ 我总是将它放在里面，我想每天都会学到新东西。 - Mike Christensen

因为您正在使用对象初始化程序，所以它将自动使用默认构造函数，因此()由编译器隐含。当然，也没有关系留下它。这只是个人喜好的问题。 :) - Christopher Currens

是的，我确实可以看出它可能是多余的。我认为我的偏好是保留它，因为我喜欢一致性。 - Mike Christensen

Answer 4

protected void Button3_Click(object sender, EventArgs e)
    {
        SqlDataReader dr = null;
        SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=shoping;User ID=sa;Password=yamini");
        con.Open();
        SqlCommand cmd = new SqlCommand("Select email from usertd where @email='" + TextBox1.Text + "' ", con);
        cmd.Parameters.AddWithValue("@email", TextBox1.Text);
        dr = cmd.ExecuteReader;
        if (dr != null && dr.HasRows)
        {
            TextBox2.Text = "abc";
        }
        else
        {
            TextBox2.Text = "hdc";
        }

    }

- janvi