How to apply async/await for event based function using webservice C#?

Question

I'm trying to call data from third-party using web-service and this will take a long time to load data so I need to apply async/await to that method, I'm calling that method in .cs, I'm using like below, when I tried with 'Void' instead of 'Task' it will take a long time to load if I use Task event will not fire.

 [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;
    }

in .cs

  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";
        }
    }

What do you mean by "in .cs"? It does make no sense at all. .cs is the extension for a C# code file. It can be found in any .Net source code project — Sir Rufo
– Sir Rufo, Commented Aug 26, 2019 at 7:36
Is you client code WinForms or WebForms? Makes a big difference. — Henk Holterman
– Henk Holterman, Commented Aug 26, 2019 at 12:18

Paulo Morgado · Accepted Answer · 2019-08-26 11:21:17Z

4

With ASP.NET Web Forms you have to register asynchronous code as a Page Task:

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;
    }
}

Check this article out:

Using Asynchronous Methods in ASP.NET 4.5

Don't use Task.Run in ASP.NET applications. It will use more resources and it will be slower.

answered Aug 26, 2019 at 11:21

Paulo Morgado

15k3 gold badges36 silver badges64 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

SomeBody · Accepted Answer · 2019-08-26 07:39:46Z

1

You will need to make your btnClaim_Click method async void, which will then await GetSuggestedItemsFromService, which should return a Task. Use async void only for event handlers. Your .cs Code should look like this:

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

    private async Task 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;
        }
    }
// Rest of your code

Moreover, the convetion is to call a method only Async if it's actually async. Hence I recommend renaming SaveAndGetSuggestedItemAsync() to SaveAndGetSuggestedItem() (it has no async keyword).

answered Aug 26, 2019 at 7:39

SomeBody

8,9102 gold badges20 silver badges38 bronze badges

3 Comments

Paulo Morgado Over a year ago

Don't use Task.Run in ASP.NET applications. It will use more resources and it will be slower.

Henk Holterman Over a year ago

Lose the Task.Run(). Superfluous and even a little harmful. suggestedItems = await SaveAndGetSuggestedItemAsync() is enough.

Henk Holterman Over a year ago

This would be a valid answer for WinForms but I don't think it will even work for WebForms (aspx).

Collectives™ on Stack Overflow

How to apply async/await for event based function using webservice C#?

2 Answers 2

Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related