Question

我想每次都使用实体框架上下文对象。什么是在asp.net中定义的更好方法？

前：

using(employeeEntities context = new employeeEntities ())
    {

    }

我想在不重用using

的情况下使用此上下文

Answer 1

虽然你可以这样做，但微软建议以不同的方式使用上下文，看看documentation：

...
The lifetime of the ObjectContext begins when the instance is created and ends when the instance is either disposed or garbage-collected. Use using if you want all the resources that the context controls to be disposed at the end of the block. When you use using, the compiler creates a try/finally block and calls dispose in the finally block. Here are some general guidelines when deciding on the lifetime of the object context:

1. When working with long-running object context consider the following:
 - As you load more objects and their references into memory, the object
   context may grow quickly in memory consumption. This may cause

   performance issues.
 - Remember to dispose of the context when it is no longer required.
 - If an exception caused the object context to be in an unrecoverable
   state, the whole application may terminate.
 - The chances of running into concurrency-related issues increase as
   the gap between the time when the data is queried and updated grows.

2. When working with Web applications, **use an object context instance per request**... 

3. When working with Windows Presentation Foundation (WPF) or Windows Forms, use an object context instance per form. This lets you use change tracking functionality that object context provides. 
...

另外，请看一下这个相关主题：One DbContext per web request... why?

Answer 2

如果你只是想要一些语法糖以避免使用using但仍然每次都创建一个新的上下文，你可以编写一些扩展方法来帮助你编写这样的代码：

// Execute is the extension method which takes the code 
// in the using block as a delegate
SomeEntities.Execute(context => 
    context.SomeTable.Where(item => item.Ammount > 100));

如果这就是您想要的，我可以与您分享代码。如果您想一直使用单个上下文，请参阅CloudyMarble的答案。

更好的定义Context对象的方法

2 个答案: