wpf 如何实现异步任务以使用异步和等待从数据库中获取数据？
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How to implement Async Task to fetch data from database using async and await?
提问by Ujaval Patel
I am doing this. It's working but is this a recommended way to do this. Please comments
我正在这样做。它正在工作，但这是推荐的方法吗？请评论
public async void LoadData()
{
DataTable dtAdditionsDetails = await LoadReportData(importID,
InkeyCommon.ToInt32(cmbSellers.SelectedValue),
fromDate,
toDate);
if (dtAdditionsDetails != null)
dtaGrdAdditions.ItemSource = dtAdditionsDetails.DefaultView;
}
public async Task<DataTable> LoadReportData(int? importID,
int sellerID,
DateTime? fromDate,
DateTime? toDate)
{
DataTable dtAdditionsDetails = new DataTable();
//Get Report Data
await Task.Delay(1);
dtAdditionsDetails = ReportsData.GetRptAdditions(importID,
sellerID,
fromDate,
toDate);
return dtAdditionsDetails;
}
采纳答案by Sheridan
In order to use the awaitkeyword properly, the object being 'awaited' should really be an ...Asyncmethod, like the GetStringAsyncmethod. As @ken2k has correctly pointed out, you cannot just awaitany method. Therefore, to answer your question is this a recommended way to do this?, the answer is no.
为了await正确使用关键字，“等待”的对象实际上应该是一个...Async方法，就像GetStringAsync方法一样。正如@ken2k 正确指出的那样，您不能只是await任何方法。因此，要回答您的问题，这是推荐的方法吗？， 答案是不。
You can find out how to use the awaitand asynckeywords correctly in the Asynchronous Programming with Async and Await (C# and Visual Basic)page on MSDN, however, if you're just trying to run a synchronous method asynchronously, then you can do that like this:
您可以在 MSDN 上的异步编程与 Async 和 Await（C# 和 Visual Basic）页面中找到如何正确使用await和async关键字，但是，如果您只是尝试异步运行同步方法，那么您可以这样做这个：
public DataTable LoadData()
{
DataTable dtAdditionsDetails = ...
// Get your data here synchronously
return dtAdditionsDetails;
}
public async Task<DataTable> LoadDataAsync()
{
DataTable dtAdditionsDetails = LoadData();
return Task.Run(() => LoadData());
}
...
...
public async void GetDataAsynchronously()
{
DataTable dtAdditionsDetails = await LoadDataAsync();
}
Note that ...Asyncmethods (usually) return Task<T>objects, rather than nothing and that their names end in the word Async. Also note that only the data is returned from ...Asyncmethods and notthe Task<T>and that we don'tawaitwhen there is nothing to await.
请注意，...Async方法（通常）返回Task<T>对象，而不是什么都不返回，并且它们的名称以单词结尾Async。还要注意，只有数据从...Async方法返回，而不是从Task<T>，当没有任何东西时我们不会。awaitawait
回答by Mike Gledhill
Here's a simple function, to load a list of all [User]records from a database, using asyncand await.
这是一个简单的函数[User]，使用async和加载数据库中所有记录的列表await。
[HttpGet]
public async Task<IActionResult> Get()
{
try
{
// Fetch a list of all the [User] records, just for the hell of it.
var users = await Task.Run(() => dbContextWebMgt.Users.ToList());
return new OkObjectResult(users);
}
catch (Exception ex)
{
return new BadRequestObjectResult(ex.Message);
}
}
回答by Bharat Bhushan Sharma
You can try like this using NPoco ORM
您可以尝试使用 NPoco ORM
[HttpGet]
public async Task<IActionResult> GetAsync()
{
IList myList = await FetchAsync();
}
