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C# Entity Framework Basics Extending Our Entity Data Model Defining a Many-to-Many Relationship

Posted by John Fouts
John Fouts
12,234 Points

I need help with understanding how to initialize a list with a constructor. I have researched for hours on the Internet

In the Entity Framework Basics course, I am having trouble with understanding how to initialize a list with a constructor. I have spent a great deal of time researching how to do this on Stack Overflow and other sites, but have not been able to accomplish successfully passing the code challenges on Treehouse. Can you please help?

Course.cs 
using System.Collections.Generic;

namespace Treehouse.CodeChallenges
{
    public class Course
    {

        public class Students()
        {
            List<Students>Students = new List<Students>();
        };


        public int Id { get; set; }
        public int TeacherId { get; set; }
        public string Title { get; set; }
        public string Description { get; set; }
        public int Length { get; set; }

        public Teacher Teacher { get; set; }
        public ICollection<Students> Students {get; set;}


//            public Human(int id, string address, string name, params ContactNumber[] contactNumbers) : this(id, address, name)
//    {
//        ContactNumbers = new List<ContactNumber>(contactNumbers);
//    }
//        
        // Using the first constructor:
//         List<ContactNumber> numbers = List<ContactNumber>() {
//         new ContactNumber(1),
//         new ContactNumber(2),
//         new ContactNumber(3)
//         };

//        A default constructor that initializes the Students property to an instance of List<Student>

    }
}
Student.cs 
namespace Treehouse.CodeChallenges
{
    public class Student
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }
}

1 Answer

Steven Parker
Steven Parker
231,072 Points
Steven Parker
Steven Parker
231,072 Points

A constructor always has the same name as the class and no type.

And remember that a default constructor takes no arguments. Then, initializing a field is just assigning it to a new instance of the type. So it might look like this:

        public Course() {
            Students = new List<Student>();
        }

You also have an error in your declaration of the field where you wrote "ICollection<Students>" (with an extra "s") instead of "ICollection<Student>".