C#•2y ago

✅ Mapping an Identity user to an instance of an EF core model ID

Any suggestions on how to make an identity user have a model ID? I need to do this so I can have a custom view for all users . My plan was to just use loops and only show content where IDs match up. Not sure where to begin.

53 Replies

Angius•2y ago

What do you mean by "model ID"? Do you have an entity Model and want to create a relationship between it and the user?

Gage•2y ago

Yes

Angius•2y ago

Then just reference it

public IdentityUser User { get; set; }

public IdentityUser User { get; set; }

Or create a custom user class if you want, by extending IdentityUser

Gage•2y ago

{
    public class IndexModel : PageModel
    {
        private readonly ApplicationDbContext _context;
        public IdentityUser Entity { get; set; }
       
       public Student Student { get; set; }
       public Teacher Teacher { get; set; }

       public IndexModel(ApplicationDbContext context)
        {
            _context = context;
        }

        public void OnGet()
        {
            Entity = _context.Users.Find(User.Identity!.Name);
            Student = _context.Students.Find(Entity.Id);
            Teacher = _context.Teachers.Find(Entity.Id);
        }
    }
}

{
    public class IndexModel : PageModel
    {
        private readonly ApplicationDbContext _context;
        public IdentityUser Entity { get; set; }
       
       public Student Student { get; set; }
       public Teacher Teacher { get; set; }

       public IndexModel(ApplicationDbContext context)
        {
            _context = context;
        }

        public void OnGet()
        {
            Entity = _context.Users.Find(User.Identity!.Name);
            Student = _context.Students.Find(Entity.Id);
            Teacher = _context.Teachers.Find(Entity.Id);
        }
    }
}

How would I get this to line up? I need to see if the Entity (The Identity User) Is the Student or the Teacher. I dont think the code I have so far would work

Angius•2y ago

You can use roles for that Instead of two different types of a user

Gage•2y ago

so we were suppose to use claims, And I have working claims. Now how would I make each individual user have a seperate instance? Example would be if a student wanted to view their specific courses or grades. how would that be done?

Angius•2y ago

await _context.Grades.Where(g => g.StudentId == id).ToListAsync();

await _context.Grades.Where(g => g.StudentId == id).ToListAsync();

Gage•2y ago

okay that creates a where clause that connects grades to student. I have that as well

Angius•2y ago

A grade would be something like

class Grade
{
    public User Student { get; set; }
    public int StudentId { get; set; }
    public User Teacher { get; set; }
    public int TeacherId { get; set; }
}

class Grade
{
    public User Student { get; set; }
    public int StudentId { get; set; }
    public User Teacher { get; set; }
    public int TeacherId { get; set; }
}

Gage•2y ago

wait a minute so I have this for my Grade

{
    public class Grade : EntityBase
    {
        [Required]
        public int StudentId { get; set; }
        public Student Student { get; set; }
        [Required]
        public int ActivityId { get; set; }
        public Activity Activity { get; set; }
        public DateTime SubmittedOn { get; set; }
        public int PointsEarned { get; set; }
        public string Comments { get; set; }

        public Grade()
        {

        }
    }
}

{
    public class Grade : EntityBase
    {
        [Required]
        public int StudentId { get; set; }
        public Student Student { get; set; }
        [Required]
        public int ActivityId { get; set; }
        public Activity Activity { get; set; }
        public DateTime SubmittedOn { get; set; }
        public int PointsEarned { get; set; }
        public string Comments { get; set; }

        public Grade()
        {

        }
    }
}

Angius•2y ago

That also works, sure My example was a very simple "teacher gives grade"

Gage•2y ago

and I have this for my student

{
    public class Student : EntityBase
    {
        public int DepartmentID { get; set; }
        public Department Major { get; set; }
        public Teacher Advisor { get; set; }
        public List<Enrollment> Enrollments { get; set; }
        public List<Grade> Grades { get; set; }
        [Required, MaxLength(100)]
        public string FirstName { get; set; }
        [Required, MaxLength(100)]
        public string LastName { get; set; }
        public DateTime DoB { get; set; }
        [Phone]
        public string Phone { get; set; }
        [EmailAddress]
        public string Email { get; set; }

        public Student()
        {
            Enrollments = new List<Enrollment>();
            Grades = new List<Grade>();
        }
    }
}

{
    public class Student : EntityBase
    {
        public int DepartmentID { get; set; }
        public Department Major { get; set; }
        public Teacher Advisor { get; set; }
        public List<Enrollment> Enrollments { get; set; }
        public List<Grade> Grades { get; set; }
        [Required, MaxLength(100)]
        public string FirstName { get; set; }
        [Required, MaxLength(100)]
        public string LastName { get; set; }
        public DateTime DoB { get; set; }
        [Phone]
        public string Phone { get; set; }
        [EmailAddress]
        public string Email { get; set; }

        public Student()
        {
            Enrollments = new List<Enrollment>();
            Grades = new List<Grade>();
        }
    }
}

so how would I make this student a user?

Angius•2y ago

You wouldn't have a student You'd just have a user You can make your student a user if you inherit from IdentityUser though

Gage•2y ago

We were given this diagram to follow, is it possible following this diagram?

Gage•2y ago

I'm implementing it incorrectly, not sure

Angius•2y ago

There's no multiple inheritance in C#

Gage•2y ago

yeah 😦

Angius•2y ago

A class can inherit only from one other class So it's impossible to recreate this graph 1:1 while using Identity at the same time

Gage•2y ago

could I make a middle man class for instances like these?

Angius•2y ago

How would that work?

Gage•2y ago

That's frustrating Think I should just ignore what the professor was saying then? He wanted us to use Identity with that, But it seems like you are saying what I was thinking in that it's not going to line up correctly

Angius•2y ago

IdentityUser has to be somewhere Either as related data, or as a parent class

Gage•2y ago

What if I made Identity user a field in student and teacher?

Angius•2y ago

You could have

class BaseUser : IdentityUser
{
    public UserType UserType { get; set; }
    public Student? Student { get; set; }
    public int? StudentId { get; set; }
    public Teacher? Teacher { get; set; }
    public int? TeacherId { get; set; }
}

enum UserType
{
    Student,
    Teacher
}

class BaseUser : IdentityUser
{
    public UserType UserType { get; set; }
    public Student? Student { get; set; }
    public int? StudentId { get; set; }
    public Teacher? Teacher { get; set; }
    public int? TeacherId { get; set; }
}

enum UserType
{
    Student,
    Teacher
}

Gage•2y ago

oh that is interesting

Angius•2y ago

And, yeah, put a nav property to BaseUser inside of both Student and Teacher

Gage•2y ago

never heard that term. What is a nav property? Same as a field?

Angius•2y ago

You'd need to at least also change the class your DbContext inherits from, from IdentityContext to IdentityContext<BaseUser> $structure

MODiX•2y ago

namespace Namespace;

[Attribute]
public class Class
{
  public string PublicField;
  private bool _privateField;
  protected double protectedField;    

  public int PublicProperty { get; set; }

  public Class() {} // Constructor

  public void Method(int parameter)
  {
    var localVariable = parameter; 
  } 
}

namespace Namespace;

[Attribute]
public class Class
{
  public string PublicField;
  private bool _privateField;
  protected double protectedField;    

  public int PublicProperty { get; set; }

  public Class() {} // Constructor

  public void Method(int parameter)
  {
    var localVariable = parameter; 
  } 
}

For C# versions older than 10, see $StructureOld

Angius•2y ago

Properties have the { get; set; }

Gage•2y ago

oh I see

Angius•2y ago

"nav properties" or "navigation properties" are an EF term for properties that point to other database models Since you can use them to navigate from one model to another

await _context.Users.Select(u => new {
  Blogs = u.Blogposts, // navigating to user's blogposts
  Categories = u.Blogposts.SelectMany(b =>
    b.Categories.Select(c => c.Name) // navigating to blogposts, then to their categories
  )
})
.ToListAsync()

await _context.Users.Select(u => new {
  Blogs = u.Blogposts, // navigating to user's blogposts
  Categories = u.Blogposts.SelectMany(b =>
    b.Categories.Select(c => c.Name) // navigating to blogposts, then to their categories
  )
})
.ToListAsync()

for example

Gage•2y ago

wait, If I am doing it like that, would I need to put ApplicationDBContext in the student and teacher Models as well?

Angius•2y ago

No, why? DbContext represents the database

Gage•2y ago

Im looking at where you did _context

Angius•2y ago

It's not a table Yeah, it's a reference to your DbContext

public class MyCoolDbContext : IdentityContext<MyUser>
{
    public DbSet<MyUser> Users { get; set; }
    public DbSet<Blogpost> Blogposts { get; set; }
    public DbSet<Category> Categories { get; set; }
}

public class MyCoolDbContext : IdentityContext<MyUser>
{
    public DbSet<MyUser> Users { get; set; }
    public DbSet<Blogpost> Blogposts { get; set; }
    public DbSet<Category> Categories { get; set; }
}

public class MyUser : IdentityUser
{
    public List<Blogpost> Blogposts { get; set; }
}

public class Blogpost
{
    public MyUser Author { get; set; }
    public string AuthorId { get; set; }
    public List<Category> Categories { get; set; }
}

public class Category
{
    public List<Blogpost> Blogposts { get; set; }
}

public class MyUser : IdentityUser
{
    public List<Blogpost> Blogposts { get; set; }
}

public class Blogpost
{
    public MyUser Author { get; set; }
    public string AuthorId { get; set; }
    public List<Category> Categories { get; set; }
}

public class Category
{
    public List<Blogpost> Blogposts { get; set; }
}

My imaginary scenario looks somewhat like this

Gage•2y ago

Oh okay, now I think I am back on track. I think I get what you mean Would this map the Identity User to the Model correctly then?

public class Student : EntityBase
    {
        public BaseUser User { get; set; }
        public int DepartmentID { get; set; }
        public Department Major { get; set; }
        public Teacher Advisor { get; set; }
        public List<Enrollment> Enrollments { get; set; }
        public List<Grade> Grades { get; set; }
        [Required, MaxLength(100)]
        public string FirstName { get; set; }
        [Required, MaxLength(100)]
        public string LastName { get; set; }
        public DateTime DoB { get; set; }
        [Phone]
        public string Phone { get; set; }
        [EmailAddress]
        public string Email { get; set; }

        public Student()
        {
            Enrollments = new List<Enrollment>();
            Grades = new List<Grade>();
        }
    }

public class Student : EntityBase
    {
        public BaseUser User { get; set; }
        public int DepartmentID { get; set; }
        public Department Major { get; set; }
        public Teacher Advisor { get; set; }
        public List<Enrollment> Enrollments { get; set; }
        public List<Grade> Grades { get; set; }
        [Required, MaxLength(100)]
        public string FirstName { get; set; }
        [Required, MaxLength(100)]
        public string LastName { get; set; }
        public DateTime DoB { get; set; }
        [Phone]
        public string Phone { get; set; }
        [EmailAddress]
        public string Email { get; set; }

        public Student()
        {
            Enrollments = new List<Enrollment>();
            Grades = new List<Grade>();
        }
    }

Angius•2y ago

Then

[Controller]
public class UserController : ControllerBase
{
    private readonly MyCoolDbContext _context;

    public UserController(MyCoolDbContext context)
    {
        _context = context;
    }

    [HttpGet]
    public async Task<List<List<string>>> GetNamesOfCategoriesForUsers()
    {
        var categories = await _context.Users.Select(u => new                   {
              Blogs = u.Blogposts, // navigating to user's blogposts
              Categories = u.Blogposts.SelectMany(b =>
                b.Categories.Select(c => c.Name) // navigating to blogposts, then to their categories
              )
            })
            .ToListAsync()
        return categories;
    }
}

[Controller]
public class UserController : ControllerBase
{
    private readonly MyCoolDbContext _context;

    public UserController(MyCoolDbContext context)
    {
        _context = context;
    }

    [HttpGet]
    public async Task<List<List<string>>> GetNamesOfCategoriesForUsers()
    {
        var categories = await _context.Users.Select(u => new                   {
              Blogs = u.Blogposts, // navigating to user's blogposts
              Categories = u.Blogposts.SelectMany(b =>
                b.Categories.Select(c => c.Name) // navigating to blogposts, then to their categories
              )
            })
            .ToListAsync()
        return categories;
    }
}

LGTM

Gage•2y ago

yeah! Okay good so I did the controllers correctly alright I am going to test this out 😅 should I drop the previous database and delete the migrations? I think I will just to be safe

Angius•2y ago

It's a big change, so yeah, probably Just make sure to commit what you have Just so you can revert the code should anything go awry

Gage•2y ago

yeah I've got several backups at this point lmfao

Angius•2y ago

Hope you're using Git, not a bunch of myproject1.zip myproject2.zip myproject3wtf.zip lol

Gage•2y ago

oh snap, So I used scaffolding to make my controllers. I should regenerate those as well since the model changed?

Angius•2y ago

Or modify them by hand

Gage•2y ago

yeah..... code gen it is haha

Angius•2y ago

Generally, it's a better idea to not use scaffolding. The code it generates is... good for tiny little test projects, but not for production, let's just say

Gage•2y ago

Is it normal to have heart palpitations here?

Angius•2y ago

With big changes? Yes 😄

Gage•2y ago

So I made an admin account and I went to add a teacher to the teacher scaffold. It does not look like its asking for a user here?

Gage•2y ago

Same with student

Gage•2y ago

That Did not work

Accord•2y ago

Closed!

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✅ Mapping an Identity user to an instance of an EF core model ID