我建设，将提供给第三方的，也用自己的Web应用程序/ s的网络API项目。在Web API方法将返回JSON重新$ P $复杂类型/对象psentations。这是pre-定义的类，我可以提供给第三方的，使他们了解数据是结构化和反序列化可以在JSON。我将把这些类作为DTO类，直到有人纠正我。

I'm building a Web API project that will be made available to third-party's and also used by my own web application/s. The Web API methods will return JSON representations of complex types/objects. These are pre-defined classes which I can make available to third-party's so they understand how the data is structured and can deserialize the JSON. I'll refer to these classes as DTO classes until someone corrects me.

我有以下的自动生成的实体模型（从数据库）以及这是User类反正有关系到扫描表（关系可以忽略这个问题的目的）......

I have the following auto-generated entity model (from database) well this is the User class anyway with a relationship to the Scan table (relationship can be ignored for the purpose of this question)...

public partial class User
{
    public User()
    {
        this.Scans = new HashSet<Scan>();
    }

    public int Id { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }
    public bool Active { get; set; }

    public virtual ICollection<Scan> Scans { get; set; }
}

和我想回到presentation层列表如下DTO类的（我不认为我应该使用IEnumerable的业务，以presentation？）。

And the following DTO class which I would like to return to the presentation layer as List (I don't think I should use IEnumerable for business to presentation?).

public class User
{
    public int Id;
    public string Username;
    public string Password;
    public bool Active;
}

我的业务层，该组件目前看起来像下面。使用LINQ to从数据库获取用户，然后分析结果并返回一个列表＆LT;> POCO用户

My business layer for this component currently looks like below. Using Linq to get users from the database and then parsing the results and returning a List<> of POCO Users.

public List<User> Get()
{
    List<User> userList = new List<User>();

    using (var db = new MyContext())
    {
        var query = from u in db.Users
                    orderby u.FirstName
                    select u;

        foreach (var item in query)
        {
            User user = new User();
            user.Id = item.pkUser;
            user.Username = item.Username;
            user.Password = item.Password;
            user.Active = item.Active;

            userList.Add(user);
        }
    }

    return userList;
}

通过解析的结果是这样似乎效率不高，我看到，你可以做这样的事情在LINQ查询没有迭代（例如，在这个问题的映射LINQ查询结果到DTO类）。

我不能确定在哪里/我应该如何实现IEnumerable在我的对象使这种类型的LINQ查询，而且我也不能确定如何编写一个类似于在引用上述问题的查询，但我多少简单的场景。

I'm unsure as to where/how I should implement IEnumerable to enable this type of Linq query on my objects, and am also unsure of how to write a query similar to the one in the referenced question above but for my much simpler scenario.

在此先感谢您的帮助。

P.S。请忽视的事实是，我通过Web API暴露用户名和密码，同时，我返回所有用户的一次。以上是我的code为这一问题的目的的简化版本。

P.S. Please ignore the fact that I am exposing Username and Password via Web API and also that I am returning all Users at once. Above is a simplified version of my code for the purpose of this question.

推荐答案

完整的方法可以是：

public List<User> Get()
{
    using (var db = new MyContext())
    {
        return (from u in db.Users
                orderby u.FirstName
                select new User()
                {
                    Id = u.pkUser,
                    Username = u.Username,
                    Password = u.Password,
                    Active = u.Active
                }).ToList();
    }
}

你说你想要的结果不重复。使用LINQ也不排除迭代。你是不是做在你的code，但是当你把它真的发生了了ToList（）方法。