Expression<Func<T, bool>>, having trouble with the Repository pattern and Entity Framework [closed]

Question

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.

---

This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.

Closed 9 years ago.

Improve this question

I've recently jumped in the Repository pattern while using Entity Framework. I wrote a basic CRUD interface that I implemented for each entity that I had. I also wanted to go further by using Expression> but there's a little problem. Enougth talk, let's show code.

Here's my User entity :

public class User
{
    public int Id { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }
}

And here's the method that annoy me a lot :

public async Task<User> FindOne(Expression<Func<User, bool>> wheres)
{
    using (MyContext context = new MyContext())
    {
        User user = await context.Users.SingleOrDefaultAsync(wheres);
        return user;
    }
}

And here's how I call it :

// user.Username is set by the user via a form
User findOne = await _usersRepository.FindOne(u => u.Username == user.Username);

The problem is that I have a null value in my variable and I'm sure that I have one record that matches my condition !

Here is a copy/paste of the "wheres" value when I step into the FindOne function :

{u => (u.Username == value(MyApi.Controllers.UsersController+<>c__DisplayClass1e).username)}

In fact, I dunno how to debug that...

Any help would be greatly appreciated. Thanks.

Answer 1

I finally find out what was the problem. In fact, the context was not properly initialized (due to a wrong DatabazeInitializer, but there were data in the DB), the code shown above is perfectly working now.