c# - 如何使用 webservice C# 为基于事件的函数应用异步/等待？

Question

我正在尝试从第三方使用网络服务调用数据，这将花费很长时间来加载数据，因此我需要应用async/await对于那个方法，我在 .cs 中调用那个方法，我正在使用如下所示，当我尝试使用“Void”而不是“Task”时，如果我使用任务事件不会触发。

 [WebMethod]
    public List<SuggestedItemsInput> SaveSuggestedItems(string emailbody, string OrderHeaderID)
    {
        List<SuggestedItemsInput> result = null;

        //... passing header and neccesery things

        request.AddParameter("application/text; charset=utf-8", strFinalEmail, ParameterType.RequestBody);
        IRestResponse restResponse = client.Execute(request);

        result = JsonConvert.DeserializeObject<List<SuggestedItemsInput>>(restResponse.Content);


        //Save to database
        if (dtProducts.Rows.Count >= 1)
            dalPendingOrders.SaveSuggestedItems(dtProducts);
        LogMessage("Suggested Items for " + OrderHeaderID + " : " + products.Products.Count);

        return result;
    }

在 .cs 中

  protected void btnClaim_Click(object sender, EventArgs e)
    {
        GetSuggestedItemsFromService();
    }

    private async void GetSuggestedItemsFromService()
    {
        List<SuggestedItemsInput> suggestedItems = await Task.Run(() => SaveAndGetSuggestedItemAsync());

        ViewState["sItems"] = suggestedItems;
        if (suggestedItems != null && suggestedItems.Count > 0)
        {
            GetSuggestedItems(Request["OrderRecordID"].ToString());
            lblInfo.Text = string.Empty;
        }
    }
    private List<SuggestedItemsInput> SaveAndGetSuggestedItemAsync()
    {
        OHDWebService OHDService = new OHDWebService();
        List<SuggestedItemsInput> suggestedItemsList = OHDService.SaveSuggestedItems(hdnPlainBody.Value, hfdOrderRecordID.Value);
        return suggestedItemsList;
    }

    private void GetSuggestedItems(string OrderRecordID)
    {
        dt = dalPendingOrders.GetSuggestedItems(OrderRecordID);
        if (dt.Rows.Count > 0)
        {
            grdSuggestedItems.DataSource = dt;
            grdSuggestedItems.DataBind();
        }
        else
        {
            lblInfo.Text = "No Data Found";
        }
    }

Answer 1

对于 ASP.NET Web 窗体，您必须将异步代码注册为页面任务:

protected void btnClaim_Click(object sender, EventArgs e)
{
    RegisterAsyncTask(GetSuggestedItemsFromService);
}

private async Task GetSuggestedItemsFromService()
{
    List<SuggestedItemsInput> suggestedItems = await SaveAndGetSuggestedItemAsync();

    ViewState["sItems"] = suggestedItems;
    if (suggestedItems != null && suggestedItems.Count > 0)
    {
        GetSuggestedItems(Request["OrderRecordID"].ToString());
        lblInfo.Text = string.Empty;
    }
}

查看这篇文章:

Using Asynchronous Methods in ASP.NET 4.5

不要在 ASP.NET 应用程序中使用 Task.Run。它将使用更多资源并且速度会更慢。