如何创建返回该类实例集合的类的构造函数？

发布于 2024-08-29 20:13:53 字数 709 浏览 2 评论 0原文

我的程序具有以下类定义：

public sealed class Subscriber
{
    private subscription;
    public Subscriber(int id)
    {
        using (DataContext dc = new DataContext())
        {
           this.subscription = dc._GetSubscription(id).SingleOrDefault();                
        }            
    }
}

，其中

_GetSubscription() 是一个 sproc，它返回 ISingleResult<_GetSubscriptionResult> 类型的值。

比如说，我有一个 List 类型的列表，其中包含 1000 个 id，并且我想创建一个 List< 类型的订阅者集合;订阅者>。

如何在不循环调用构造函数 1000 次的情况下做到这一点？

因为我试图避免频繁地打开/关闭 DataContext，这可能会给数据库带来压力。

TIA。

原文

My program has the following class definition:

public sealed class Subscriber
{
    private subscription;
    public Subscriber(int id)
    {
        using (DataContext dc = new DataContext())
        {
           this.subscription = dc._GetSubscription(id).SingleOrDefault();                
        }            
    }
}

,where

_GetSubscription() is a sproc which returns a value of type ISingleResult<_GetSubscriptionResult>

Say, I have a list of type List<int> full of 1000 ids and I want to create a collection of subscribers of type List<Subscriber>.

How can I do that without calling the constructor in a loop for 1000 times?

Since I am trying to avoid switching the DataContext on/off so frequently that may stress the database.

TIA.

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冧九 2024-09-05 20:13:53

编写一个调用私有构造函数的静态工厂方法。

public sealed class Subscriber
{
    // other constructors ...

    // this constructor is not visible from outside.
    private Subscriber(DataContext dc, int id)
    {
       // this line should probably be in another method for reusability.
       this.subscription = dc._GetSubscription(id).SingleOrDefault();                
    }

    public List<Subscriber> CreateSubscribers(IEnumerable<int> ids)
    {
        using (DataContext dc = new DataContext())
        {

           return ids
             .Select(x => new Subscriber(dc, x))
             // create a list to force execution of above constructor
             // while in the using block.
             .ToList();
        }            

    }

}

Write a static factory method which calls a private constructor.

public sealed class Subscriber
{
    // other constructors ...

    // this constructor is not visible from outside.
    private Subscriber(DataContext dc, int id)
    {
       // this line should probably be in another method for reusability.
       this.subscription = dc._GetSubscription(id).SingleOrDefault();                
    }

    public List<Subscriber> CreateSubscribers(IEnumerable<int> ids)
    {
        using (DataContext dc = new DataContext())
        {

           return ids
             .Select(x => new Subscriber(dc, x))
             // create a list to force execution of above constructor
             // while in the using block.
             .ToList();
        }            

    }

}

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