The property 'x' is not a navigation property of entity type 'y'

Question

I'm using EF Core with ASP Core 2.0. Using latest Identity framework. I get this exception on page All.

InvalidOperationException: The property 'User' is not a navigation property of entity type 'Gallery'. The 'Include(string)' method can only be used with a '.' separated list of navigation property names.

ApplicationUser looks like:

public class ApplicationUser : IdentityUser<Guid>
{
    public ICollection<Gallery> Galleries { get; set; }
}

Entity Gallery looks like:

public class Gallery
{
    public int Id { get; set; }
    public Guid UserId { get; set; }
    public string Title { get; set; }
    public int? ArticleId { get; set; }
    public string Photos { get; set; }
    public DateTime CreatedAt { get; set; }
    public DateTime UpdatedAt { get; set; }

    public Article Article { get; set; }
    public ApplicationUser User { get; set; }

    [NotMapped]
    public List<string> PhotosList
    {
        get { return Photos?.Split('|').ToList(); }
        set { Photos = string.Join("|", value); }
    }
}

Controller for View looks like:

public async Task<IActionResult> All()
    {
        var databaseContext = db.Galleries.Include(x => x.Article).Include(x => x.User);

        return View(await databaseContext.ToListAsync());
    }

I have no idea why it dont crash on Article..

Database is up-to-date.

Answer 1

add a ForeignKey attribute

using System.ComponentModel.DataAnnotations.Schema;

...

[ForeignKey("Article")]
public int? ArticleId { get; set; }

[ForeignKey("User")]
public Guid UserId { get; set; }

You can also put the attribute on the navigation property

[ForeignKey("UserId")]
public ApplicationUser User { get; set; }

---

Also, make sure your dbContext inherits from IdentityDbContext<ApplicationUser, ...>