Web服务调用循环/未完成

Question

For my app I make calls to a web service to get customer data. The problem I am encountering is when I make this particular call it gets the the asynchronous await call and loops back without finishing the call and then storing the results.

private void DatabaseTest()
{
    cNum = Convert.ToString(db.selectCustomerNumber());
    callC = "SELECT * FROM dashboardCustomer WHERE period = 'C' AND customerNumber = " + cNum;
    callB = "SELECT * FROM dashboardCustomer WHERE period = 'B' AND customerNumber = " + cNum;
    callF = "SELECT * FROM dashboardCustomer WHERE period = 'F' AND customerNumber = " + cNum;
    if (db.selectDashboard(callC).Count == 0)
    {
        GetDataSummary(passC);
    }
    if (db.selectDashboard(callB).Count == 0)
    {
        GetDataSummary(passB);
    }
    if (db.selectDashboard(callF).Count == 0)
    {
        GetDataSummary(passF);
    }
}

    private async void GetDataSummary(string r)
    {

        long customerNum = db.selectCustomerNumber();
        pin = db.selectPinByCustomerNumber(customerNum);

        string cType = r;
        try
        {
            Windows.Security.Credentials.PasswordVault vault = new Windows.Security.Credentials.PasswordVault();
            IReadOnlyList<PasswordCredential> userCredential = vault.FindAllByResource(pin);

            userCredential[0].RetrievePassword();

            try
            {
                getCustomerBillSummaryResponse billSum = await
                    UBPclient.getCustomerBillSummaryAsync(userCredential[0].UserName, userCredential[0].Password, customerNum, cType);

                invoiceSummaryBean[] summaryList = billSum.@return;

                rh.DashboardHandler(summaryList, customerNum);


            }
            catch
            {

            }
        }
        catch
        {

        }

    }

it runs to the following part

getCustomerBillSummaryResponse billSum = await
                    UBPclient.getCustomerBillSummaryAsync(userCredential[0].UserName, userCredential[0].Password, customerNum, cType);

and then loops back to the try and runs again until it has ran three times.

How do I make it return the data it is suppose to for each call and store it in my database?

Also I have tested the web service in SoapUI and the call is returning results, so the problem is not with the web service.

Answer 1

You need to do this:

private async Task GetDataSummary(string r)

You need to return Task instead of void because your caller needs to have something to wait for. When you return void , the caller must treat method as "fire-and-forget". When you return Task , the caller can create the necessary code to await for async method to finish.

And don't forget to add the await keyword when you call it: await GetDataSummaryAsync(...);

Answer 2

You should avoid async void . Change GetDataSummary to return Task and then await it from DatabaseTest :

private async Task DatabaseTestAsync()
{
    ...
    if (db.selectDashboard(callC).Count == 0)
    {
        await GetDataSummaryAsync(passC);
    }
    if (db.selectDashboard(callB).Count == 0)
    {
        await GetDataSummaryAsync(passB);
    }
    if (db.selectDashboard(callF).Count == 0)
    {
        await GetDataSummaryAsync(passF);
    }
}

private async Task GetDataSummaryAsync(string r)