EF 5：如何在异步任务中取消朗读查询 [英] EF 5: How to cancel a longrunning query in a async Task

问题描述

在我的应用程序中，我有多个选项卡，使用Entity Framework 5从数据库显示数据。

In my application I have multiple tabs, displaying data from a database with Entity Framework 5.

当我在选项卡之间切换时，我开始自动加载数据任务，因为我不希望GUI无响应（这个任务需要5-10秒）：

When I switch between the tabs I start auto loading the data via a Task, because I don't want the GUI to become unresponsive (this task takes about 5-10 seconds):

public async void LoadData()
{
    [...]

    await Task.Run(
        () =>
            {
                Measurements = DataContext.Measurements
                                  .Where(m => m.MeasureDate = DateTime.Today)
                                  .ToList();
            });

    [...]
}

但是任务运行用户仍然可以更改为另一个选项卡，如果他这样做，我想取消EF查询和/或任务。

But while the task runs the user still can change to another tab, and if he does that I would like to cancel the EF query and/or the Task.

什么是最好的方式来完成这个？

What would be the best way to accomplish this?

推荐答案

在EF5中，无法取消查询，因为它不接受的CancellationToken 。您可以在这里阅读更多信息：实体框架取消长时间运行的查询

In EF5, there is no way to cancel the queries since it doesn't accept CancellationToken. You can read more about this here: entity framework cancel long running query

但是，EF6确实支持它。

However, EF6 does support it.

它具有所有方法的异步版本。所以 ToList（）可以代替 ToListAsync（）长时间运行的查询，它确实支持 CancellationToken 。

It has async version of all methods. So ToList() could instead be ToListAsync() for long running queries and it does have support for CancellationToken.

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