ASP .Net Core Error CS1061 ICollection Error

Question

I am working on a project where part of the functionality is to associate the suburbs of cities with their parent city. For example, I live in Grandview, Ohio, which is a suburb of Columbus, Ohio (the state capital).

I a using ASP .Net Core 2.2 Razor Pages (non-MVC), EF Core, and SQL Server.

My IDE is VS 2019.

I have two classes:

 public class City
    { 

        [Key]
        public int Id { get; set; }

        [Required]
        [Display(Name = "City")]
        public string Description { get; set; }

        public int StateID { get; set; }
        [ForeignKey("StateID")]
        public virtual State State { get; set; }

        public int? ParentCityId { get; set; }
        [ForeignKey("ParentCityId")]
        public virtual ParentCity ParentCity { get; set; }

    }

City is the suburb (Grandview in my example)

 public class ParentCity
    {

        public ParentCity()
        {
            this.Cities = new HashSet<City>();
        }

        [Key]
        public int Id { get; set; }

        [Required]
        public string Description { get; set; }

        public ICollection<City> Cities { get; set; }

    }

Parent City is the major city (Columbus, in my example)

Here is my Index.cshtml Page Model:

public class IndexModel : PageModel
    {
        [TempData]
        public string StatusMessage { get; set; }

        private readonly Data.ApplicationDbContext _context;

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

        public ICollection<ParentCity> ParentCity { get; set; }

        public async Task<IActionResult> OnGetAsync()
        {
            ParentCity = await _context.ParentCity
                                       .Include(c => c.Cities)
                                       .OrderBy(c => c.Description)
                                       .AsNoTracking()
                                       .ToListAsync();

            return Page();
        }
    }

This SQL selects all of the Parent Cities in the database table, and their associated City.

I have the following data in the tables:

Parent City:
Id = 1
Description = "Columbus"

City:
Id = 1 Grandview
ParentCityId = 1

Id = 2 Worthington
ParentCityId = 1

In my index.cshtml I have the following code:

 @foreach (var item in Model.ParentCity)
      {
       <tr>
           <td class="align-middle">
           @Html.DisplayFor(modelItem => item.Description)
           </td>
           <td class="align-middle">
           @Html.DisplayFor(modelItem => item.Cities.Description)
           </td>                            
       </tr>
       }

On the line:

@Html.DisplayFor(modelItem => item.Cities.Description)

I am getting the following error:

CS1061 'ICollection<City>' does not contain a definition for 'Description' and no accessible extension method 'Description' accepting a first argument of type 'ICollection<City>' could be found (are you missing a using directive or an assembly reference?)

Any help appreciated in explaining why I am getting this error. I have been looking at it for hour, and cannot figure out. Google has not been my friend.

Thanks.

Answer 1

The error is in your cshtml:

@Html.DisplayFor(modelItem => item.Cities.Description)

You are trying to access the Description property of Cities - but Cities is an ICollection.

One was to fix it is to change your foreach to loop over the cities and print the values for each city:

@foreach (var item in Model.ParentCity.Cities)
{
    <tr>
        <td class="align-middle">
            @Html.DisplayFor(modelItem => item.ParentCity.Description)
        </td>
        <td class="align-middle">
            @Html.DisplayFor(modelItem => item.Description)
        </td>                            
     </tr>
}