How to show category name instead of categoryId in view from another table in asp.net core 3.1 mvc?

Question

I have two different tables one of them is Titles other one is Categories. Titles have 4 columns as Name, OWS, TWS, and CategoryId Categories have 3 columns as Id, Name, ParentName.

I want to show the Category Name on the Titles table instead of CategoryId.

I search and I see some solutions by using Foreign Key. CategoryId is not defined as FK. But I cannot change the tables from db because of authentication issues.

First of all, I declared virtual categories in Titles Model

public class Titles
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string OWS { get; set; }
    public string TWS { get; set; }
    public Guid CategoryId { get; set; }

    public virtual Categories Category { get; set; }
}

Then I work with TitlesController Index() method. When I write CategoryId=m.CategoryId, I see the categoryIds on the Titles Table. And I think that if I use Category.Name instead of CategoryId, I can see the CategoryName in the Titles Table. In this case I get convert type error as string to system guid.

public async Task<IActionResult> Index()
    {

        var titles = _context.Titles
                            .Select(m => new Titles()
                            {
                                //Id=m.Id,
                                Name = m.Name,
                                OWS = m.OWS,
                                TWS = m.TWS,
                                CategoryId=m.Category.Name
                            });

       
        return View(await titles.ToListAsync());

    }

I think, converting CategoryName to Guid is not make sense and also converting CategoryId to string can be ruined the other parts of the project.

As a result, how can I show the category name instead of categoryId without using FK?

Answer 1

you can add a property in your model as NotMapped like below

public class Titles
{
  public Guid Id { get; set; }
  public string Name { get; set; }
  public string OWS { get; set; }
  public string TWS { get; set; }
  public Guid CategoryId { get; set; }

  [NotMapped]
  public string CategoryName { get; set; }
  public virtual Categories Category { get; set; }
}

and for logic as below

var titles = _context.Titles.Include(t=>t.Category)
                        .Select(m => new Titles()
                        {
                            //Id=m.Id,
                            Name = m.Name,
                            OWS = m.OWS,
                            TWS = m.TWS,
                            CategoryName=m.Category.Name
                        });

also you can make a separate Dto instead of Not Mapped property and use it direct as model of your view

Answer 2

you must use NotMapped attribute

public class Titles
{
  public Guid Id { get; set; }
  public string Name { get; set; }
  public string OWS { get; set; }
  public string TWS { get; set; }
  public Guid CategoryId { get; set; }
  [NotMapped]
  public string CategoryName
  public virtual Categories Category { get; set; }
}

and

var titles = _context.Titles.Select(m => new Titles()
{
 Name = m.Name,
 OWS = m.OWS,
 TWS = m.TWS,
 CategoryName=m.Category.Name
});