实体框架导航属性错误

问题描述

我在我的.Net MVC 4 Web应用程序收到此错误：

I am getting this error in my .Net MVC 4 web application:

The property 'Username' cannot be configured as a navigation property. The
property must be a valid entity type and the property should have a non-abstract
getter and setter.  For collection properties the type must implement
ICollection<T> where T is a valid entity type.

我很新的实体框架和我似乎无法来解决这个问题。下面是一些code：

I am very new to Entity Framework and I can't seem to get around this issue. Here is some code:

//DB Context
public class EFDbContext : DbContext
{
    public DbSet<User> Users { get; set; }
    public DbSet<Role> Roles { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<User>().HasMany(u => u.Roles).WithMany(r => r.Users).Map(x => x.MapLeftKey("Username").MapRightKey("RoleName").ToTable("Users_Roles"));
    }

}

//Entity Classes

public class User
{
    [Key]
    public string Username { get; set; }
    public string Password { get; set; }
    public string Email { get; set; }
    public string Comment { get; set; }
    public int Level { get; set; }
    public string PasswordQuestion { get; set; }
    public string PasswordAnswer { get; set; }
    public bool IsApproved { get; set; }
    public DateTime LastActivityDate { get; set; }
    public DateTime LastLoginDate { get; set; }
    public DateTime LastPasswordChangedDate { get; set; }
    public DateTime CreationDate { get; set; }
    public bool IsOnLine { get; set; }
    public bool IsLockedOut { get; set; }
    public DateTime LastLockedOutDate { get; set; }
    public int FailedPasswordAttemptCount { get; set; }
    public DateTime FailedPasswordAttemptWindowStart { get; set; }
    public int FailedPasswordAnswerAttemptCount { get; set; }
    public DateTime FailedPasswordAnswerAttemptWindowStart { get; set; }

    [InverseProperty("RoleName")]
    public virtual ICollection<Role> Roles { get; set; }

    public override string ToString()
    {
        return this.Username;
    }
}

public class Role
{
    [Key]
    public string RoleName { get; set; }
    public int Level { get; set; }

    [InverseProperty("Username")]
    public virtual ICollection<User> Users { get; set; }

    public override string ToString()
    {
        return this.RoleName;
    }

}

//Repository
public class EFUsersRepository : IUsersRepository
{
    private EFDbContext context = new EFDbContext();

    public IQueryable<User> Users
    {
        get { return context.Users; }
    }

    public User GetUser(string username)
    {
        return context.Users.Find(username); //THIS IS WHERE THE CRASH OCCURS
    }
}

//DB Setup
Table Users, Role and Users_Role. Users_Role is a simple linking table with [username, role] columns both of type varchar.

The database tables columns & types match the two classes above (User,Role).

我继承了这个项目，这是未完成的，但我不能让它成功运行。任何帮助了解什么问题会很有帮助。谢谢！

I inherited this project which was unfinished but I can't get it to run successfully. Any help understanding what the issue is would be helpful. Thanks!

推荐答案

原来，注释掉足够的项目整天之后，下面的线是什么导致了这个错误我：

It turns out, after commenting out enough items all day long, the the following lines are what caused this error for me:

[InverseProperty("RoleName")] //In file User.cs (as shown above)
[InverseProperty("UserName")] //in file Role.cs (as shown above)

我仍然在学习实体框架和我不知道为什么这是解决方案，但它停止我在上面报告的错误。

I am still learning Entity Framework and I don't know why this was the solution, but it stopped the error which I reported above.

我希望这可以帮助别人，如果有人想帮助我了解什么问题是详细，请随意。我渴望学习。

I hope that this helps someone else and if anyone wants to help me understand what the issue was in detail, please feel free. I am eager to learn.

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