问题描述
我正在使用带有EF-6的asp.net MVC-5，并且不确定使用await + ToListAsync是否有效.例如，我有以下存储库方法可返回IQueryable:-
I am using asp.net MVC-5 with EF-6, and I am not sure if using await + ToListAsync is valid. For example, I have the following repository method which returns an IQueryable :-
public IQueryable<TSet> getAllScanEmailTo()
{
return t.TSets.Where(a=>a.Name.StartsWith("ScanEmail"));
}
我这样称呼它:-
var emailsTo = await repository.getAllScanEmailTo().ToListAsync();
一开始，我以为会出错，因为我使用的是"await"方法，该方法未定义为任务，但是上述方法效果很好，所以任何人都可以对此提出建议吗?
In the beginning, I thought I will get an error because I am using "await" a method which is not defined as a task, but the above worked well, so can anyone advice on this, please ?
推荐答案
实际上，您是正在等待一个返回Task<T>的方法，其中T是List<TSet>.如果您查看扩展方法 QueryableExtensions.ToListAsync ，您会看到它返回了Task<List<TSource>>.您正在异步等待此方法来查询数据库，创建列表并将其返回给调用方.当您在这样的方法上await时，该方法将不会返回，直到操作完成. async-await 使您的代码感到同步，而执行实际上是异步的.
Actually, you are awaiting a method which returns a Task<T>, where T is a List<TSet>. If you look at the extension method QueryableExtensions.ToListAsync, you'll see that it returns a Task<List<TSource>>. You are asynchronously waiting on this method to query the database, create the list and return it back to the caller. When you await on such a method, the method wont return until the operation has completed. async-await makes your code feel synchronous, while execution is actually asynchronous.
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