EF Core question regarding relations

Question

I'm building a ticket system.

I have two models: User and Ticket. A user can have multiple tickets, and is bound to the ticket via the Customer_Id field. Another user, with the role of Practitioner, can also be assigned to the ticket, via the Practitioner_Id field.

Here's a simplified version of those classes:

  public class User
    {
        public long UserId { get; set; }
    }




public class Ticket
{
    public long TicketId { get; set; }

    [ForeignKey("Customer")]
    public long Customer_Id { get; set; } //User.UserId (the customer)
    public User Customer { get; set; }

    [ForeignKey("Practitioner")]
    public long? Practitioner_Id { get; set; }// User.UserId (the practitioner)
    public User Practitioner { get; set; }
}

Now so far so good. When a migration is created, there's a foreign key for both Customer_Id and Pratitioner_Id to the Users table.

Now I want to have a List<Ticket> on the user model, so I can write a seeder for users with some tickets.
But how do I make clear that that List<Ticket> must refer to the tickets for which Customer_Id is equal to that user's UserId?

in other words:

public class User
{
    public long UserId { get; set; }
    public List<Ticket> tickets {get;set;} // must do: select * from tickets where Customer_Id = <this.UserId>
}

Answer 1

Hi Daniel,

with a seeder class you can initialize a database's content, so if you spin up a development environment with your sourcecode and database, the seeder class inserts data for you so you don't have to insert test records yourself every time.

In this case, I like the seeder to be able to insert a few test-users with each a few tickets. I've done this in the past with other projects like this:

using BasicAPI.EFModels;
using BasicAPI.EFModels.TestModels;
using BasicAPI.Enums;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace BasicAPI.Seeders
{
    public class Seeder // SIMPLYFIED
    {
        private MyDBContext _context;

        public Seeder(MyDBContext c)
        {
            _context = c;
        }

        public async Task Seed()
        {

            bool changesMade = false;

            if (!_context.users.Any())
            {
                _context.users.AddRange(_users);
                changesMade = true;
            }



            if (changesMade)
                await _context.SaveChangesAsync();
            }

        }



        List<User> _users
        {
            get
            {
                List<User> result = new List<User>();

                // TEST USER
                User customer = new User()
                {
                    firstName = "Cus",
                    lastName = "Tomer",
                    userName = "customer",
                    passWord = "testtest",

                    // THE CODE BELOW WORKS, EACH TestObject AUTOMATICALLY GETS AN ID, AND AUTOMATICALLY GETS ITS UserId PROPERTY ASSIGNED TO 
                    // THE UserId OF THE USER WHICH IS INSERTED IN THE SAME STATEMENT.:
                    // THIS WORKS BECAUSE IT'S IMMEDIATELY OBVIOUS THAT TestObject.UserId MAPS TO User.UserId.

                    TestObjects = new List<TestObject>() {
                        new TestObject
                        {
                            Test = "A test object",
                            CreateDate = DateTime.Now
                        },
                        new TestObject
                        {
                            Test = "Another test object",
                            CreateDate = DateTime.Now
                        }
                    }

                    // HOWEVER FOR MY TICKET CLASS IT'S NOT WORKING BECAUSE A TICKET DOES NOT HAVE A UserId, BUT A CustomerId AND A PractitionerId.
                    // SO HOW DO I LET EF.CORE KNOW THAT WHEN I MAKE A List<Ticket>, THAT IS NEEDS TO GET THE TICKETS BASED ON Ticket.CustomerId = this.UserId ?
                };

                customer.HashPassword();
                result.Add(customer);

                return result;
            }
        }


    }

    public class TestObject // SIMPLYFIED
    {
        public long TestObjectId { get; set; }

        public long UserId { get; set; }
        public User User { get; set; }
    }

    public class User // SIMPLYFIED
    {
        public long UserId { get; set; }

        public List<TestObject> TestObjects { get; set; }
    }
}