many to many Entity Framework GetUsersInRole()

Question

我有两个实体类型:Role和User，它们具有多对多关系。即角色具有Users属性，而用户具有Roles属性。我必须获得包含属于定义角色的用户名的字符串数组。我写了一些代码，但并不优雅。我想用一个linq表达式来做。这可能吗?

public override string[] GetUsersInRole(string roleName)
{
    List<string> names = new List<string>();
    using (MembershipDb db = new MembershipDb())
    {
        Role role = db.Roles.FirstOrDefault(r => r.Name == roleName);
        foreach (User u in role.Users)
        {
            names.Add(u.UserName);
        }
    }
    return names.ToArray();
}

Answer 1

return db.Roles.Where(r => r.Name == roleName)
               .SelectMany(r => r.Users)
               .Select(u => u.UserName)
               .ToArray();

Answer 2

看这个:

public override string[] GetUsersInRole(string roleName)
{
    using (MembershipDb db = new MembershipDb())
    {
        return db.Roles
           .Where(r => r.Name == roleName)
           .SelectMany(r => r.Users, (r, s) => s.User.UserName).ToArray();
    }
}