通过单击表单上的ac＃asp.net按钮，如何在继续执行下一行代码之前执行一行代码？

Question

Using c# code, I have a button on a webpage which will run a PowerShell process (see code below). This process takes a little while to run, so when I click the button I would like to display a message in a label stating that the process is running. then once the process has finished, change the label message to state that the process ahs finished. My current code is:

protected void button_Click(object sender, EventArgs e)
        {
            label.Text = "Running Process...";

            ProcessStartInfo startInfo = new ProcessStartInfo();
            startInfo.FileName = @"powershell.exe";
            startInfo.Arguments = @"C:\PowerShell\script.ps1";
            startInfo.RedirectStandardOutput = true;
            startInfo.RedirectStandardError = true;
            startInfo.UseShellExecute = false;
            startInfo.CreateNoWindow = true;
            Process process = new Process();
            process.StartInfo = startInfo;
            process.Start();

            label.Text = "Finished Process. ";

      }

This currently does not display the initial message of "Running Process...". It just runs through the whole code and displays the "Finished Process" message.

So I need a way of committing the first line of code to fill the label and then move on to the rest of the code but am stuck as to how to do this???

Any help please is appreciated.

Johnathan.

Answer 1

You could use AJAX to get this done.

You could post it using jquery/ajax, set the message you want on begin of the process and and finish message when the process finishes.

Answer 2

Aspx code

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">

<script type="text/javascript">

    function BeginProcess() {
        // Create an iframe.
        var iframe = document.createElement("iframe");

        // Point the iframe to the location of
        //  the long running process.
        iframe.src = "Process.aspx";

        // Make the iframe invisible.
        iframe.style.display = "none";

        // Add the iframe to the DOM.  The process
        //  will begin execution at this point.
        document.body.appendChild(iframe);

        // Disable the button and blur it.
         document.getElementById('trigger').blur();
    }

    function UpdateProgress(PercentComplete, Message) {
        document.getElementById('ContentPlaceHolder2_lbDownload').setAttribute("disabled", "true");
        document.getElementById('trigger').value = PercentComplete + '%: ' + Message;

    }


  </script>
 </asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder2" Runat="Server">
 <asp:UpdatePanel ID="UpdatePanel1" runat="server">
 <ContentTemplate>

  <input type="submit" value="Start BackUp Process!" 
id="trigger" onclick="BeginProcess(); return false;"
style="width: 250px;" />

</ContentTemplate>
 </asp:UpdatePanel>


  <asp:UpdateProgress ID="UpdateProgress1" 
 AssociatedUpdatePanelID="UpdatePanel1" runat="server">
<ProgressTemplate>  
     </ProgressTemplate> 
</asp:UpdateProgress>


 </asp:Content>

Code behind .cs code

 public partial class Process : System.Web.UI.Page
 {
  protected void Page_Load(object sender, EventArgs e)
{

    StringBuilder SB = new StringBuilder();
    // Padding to circumvent IE's buffer.
    Response.Write(new string('*', 256));
    Response.Flush();

    // Initialization
    UpdateProgress(0, "Initializing task.");


    try
    {


        foreach (yourloophere)
        {

                    UpdateProgress(increment, db.Name + " Backup Started....");
            //your process code
                    UpdateProgress(increment, db.Name + " Backup Completed!");

//your process code SB.Append(db.Name + "BackUp Complted!");

    //your process code
            SB.Append("<br/>");



        }


        // All finished!
        UpdateProgress(100, "All Database BackUp Completed!");

    }
    catch (Exception ex)
    {
        UpdateProgress(0, "Exception: " + ex.Message);

        SB.Append("Back Up Failed!");
        SB.Append("<br/>");
        SB.Append("Failed DataBase: " + DBName);
        SB.Append("<br/>");
        SB.Append("Exception: " + ex.Message);

    }


}


protected void UpdateProgress(double PercentComplete, string Message)
{
    // Write out the parent script callback.
    Response.Write(String.Format("<script type=\"text/javascript\">parent.UpdateProgress({0}, '{1}');</script>", PercentComplete, Message));
    // To be sure the response isn't buffered on the server.    
    Response.Flush();
}


 }

Answer 3

Have a look at the asp lifecycle. You cant change the page via serverside code without doing a postback. Thats what you are doing when clicking an asp button, etc..

If you want to show a loading indicator youll have to create it before running the long running code. Otherwise the indicator will never be shown to the user because he does not receive a new page.

Here you have 2 options - do a postback place the loading indicator and do another postback (I would not recommend that) or just show something via JS.

I created a Weave to show you the basic functionality. -- stolen from http://oracleinsights.blogspot.de/2009/12/how-to-create-loading-indicator_13.html

This will show a loading indicator serverside code is running.

Answer 4

You can try adding inline javascript code to change the label.

<asp:Button ID="button" runat="server" OnClick="button_Click" Text="Click" 
    OnClientClick="this.value = 'Running Process...'" />

This will appear the moment you click the button and then the label will change to Finished Process. when the page is reloaded.

Answer 5

You can do this on ajax,

function ShowProcessing()
{
    $('#label').text('Running Process...');
    // call pagemethod with your functionality
    // Let's success callback is OnSuccess
}

function OnSuccess()
{
     $('#label').text('Finished Process.');
}