A specified Include path is not Valid. The Entitytype 'Model.User' does not declare a navigation Property with the name 'Connections'

Question

I’m following this example to maintain connection and user information in a database.

So I created 2 tables:

dbo. User:

dbo. Connection:

These 2 tables above are very simple. I only created as a primary key.

Then I created a new "ADO.NET Entity Data Model" item in the "Models" folder".

Model.Context.Cs: (Dbcontext)

public virtual DbSet<Connection> Connections { get; set; }
public virtual DbSet<User> Users { get; set; }

Connection.Cs:

public partial class Connection
{
    public string ConnectionID { get; set; }
    public string UserAgent { get; set; }
    public bool Connected { get; set; }
}

User.Cs:

public partial class User
{
    public string UserName { get; set; }
    //Adicionei esse novo código abaixo:
    public ICollection<Connection> Connections { get; set; }
}

I get the following error:

Additional information: A specified Include path is not valid. The EntityType 'Model.User' does not declare a navigation property with the name 'Connections'.

Follows the code:

public override Task OnConnected()
{
    var name = Context.User.Identity.Name;
    using (var db = new Entities())
    {
        var user = db.Users.Include(u => u.Connections).SingleOrDefault(u => u.UserName == name);

        if (user == null)
        {
            user = new User
            {
                UserName = name,
                Connections = new List<Connection>()
            };
            db.Users.Add(user);
        }

        user.Connections.Add(new Connection
        {
            ConnectionID = Context.ConnectionId,
            UserAgent = Context.Request.Headers["User-Agent"],
            Connected = true
        });
        db.SaveChanges();
    }
    return base.OnConnected();
}

The problem is occurring on the line: var user = db.Users.Include(u => u.Connections).SingleOrDefault(u => u.UserName == name);.

Some solution ?

Answer 1

To navigation Property "Connections" should be declared as virtual:

public partial class User
{
    public string UserName { get; set; }
    //Adicionei esse novo código abaixo:
    public virtual ICollection<Connection> Connections { get; set; }
}