实体框架查询多对多

Question

I have the following database table structure.

User
----
userid
username
firstname
lastname

Role
----
RoleId
Name
Description

UserRole
--------
UserRoleId
UserId
RoleId

Can anyone help me how to properly design the datadomain classes to use in EF so that when i get the User i also get the rolename and roledescription?

Many Thanks

Answer 1

The UserRole table does not need to have Id , the primary key is the combination of other two foreign keys, so the model should be:

public class User 
{
    public int UserId { get; set; }
    public string UserName{ get; set; }
    public string FirstName {get; set;}
    public string LastName {get; set;}

    public virtual ICollection<Role> Roles { get; set; }
}
public class Role
{
    public int RoleId { get; set; }
    public string Name{ get; set; }
    public string Description{get; set;}

    public virtual ICollection<User> Users{ get; set; }
}

EF will generate the tables for two above entities and creates a new table for many-to-many relationship, which contains the two Primary keys of above entities.

but is you want the intermediate UserRole table have Id , then :

public class User 
{
    //Some properties
    public virtual ICollection<UserRole> UserRoles { get; set; }
}
public class Role
{
    public virtual ICollection<UserRole> UserRoles{ get; set; }
}
public class Role
{
    public int UserRoleId { get; set; }

    public int UserId { get; set; }
    public virtual User User { get; set; }

    public int RoleId { get; set; }
    public virtual Role Role { get; set; }
}