Linq查询引用不同的上下文，但实际上不是

Question

I am trying to get data from two different tables using EF 6, it is a asp.net mvc 5 project with Identity 2.0 used in it, however when i join two tables, i am getting the error that contexts of both entities are different, however it is not, here is my code:

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public ApplicationDbContext()
        : base("DefaultConnection", throwIfV1Schema: false)
    {
    }

    public DbSet<UserAccountStatus> UserAccountStatuss { get; set;}

    public static ApplicationDbContext Create()
    {
       return new ApplicationDbContext();
    }
}

and here is my linq query :

var result = (from user in DbContext.Users
              join accountStatus in DbContext.UserAccountStatuss on user.Id equals accountStatus.UserId
              where user.Email == email
              select accountStatus.AccountEnabled).FirstOrDefault();

My DbContext property:

public ApplicationDbContext DbContext
{
    get
    {
        return _dbContext ?? ApplicationDbContext.Create();
    }
    private set
    {
        _dbContext = value;
    }

}

Exact error is :

The specified LINQ expression contains references to queries that are associated with different contexts.

and this is not a duplicate, i have seen other questions, in those user are actually trying different contexts, but in my case i have one.

Answer 1

your lazy instantiaiton is the problem. It should be

private ApplicationDbContext _dbContext;
public ApplicationDbContext DbContext
{
    get
    {
        if(_dbContext==null){_dbContext=ApplicationDbContext.Create();}
        return _dbContext;
    }


}

Edit: Example with Lazy

private Lazy<ApplicationDbContext> _dbContext=new Lazy<ApplicationDbContext>(()=>ApplicationDbContext.Create());
public ApplicationDbContext DbContext
{
    get
    {
        return _dbContext.Value;
    }


}

Answer 2

public ApplicationDbContext DbContext
{
    get
    {
        return _dbContext ?? ApplicationDbContext.Create();
    }
    private set
    {
        _dbContext = value;
    }

}

You get a new context every time...

public ApplicationDbContext DbContext
{
    get
    {
        if(_dbContext == null)
            _dbContext = ApplicationDbContext.Create();
        return _dbContext;
    }    
}

Try this

Answer 3

Your property will return a new context each time it is accessed. You need to store the newly created context so it can be returned the next time it is used.