ASP.NET: How to trigger click event for the button before page loads

Question

I have a page that has two buttons. Each button when clicked will update a database table. Updated value should be displayed next time the page loads.

Now, when clicking the button, my page_load event fires first, keeping old values taken from the session.

How can I change that so new values will be displayed?

This is some of my code:

Page_Load:

private void Page_Load(object sender, System.EventArgs e)
{

    myDataSet = Session["myDataset"] as DataSet;

    if( myDataSet != null && myDataSet.Tables[0].Rows.Count > 0 )
    {
        myDBType = myDataSet.Tables[0].Rows[0]["dbType"].ToString();
    }
    else
    {
        myDBType = Connection.GetDBType(someid);
    }

    string displayStatus = "Value1: " + myID.Tables[0].Rows[0][0].ToString() +
        " Value2: " + myDataSet.Tables[0].Rows[0][1].ToString() +
        " Value3: " + myDataSet.Tables[0].Rows[0][5].ToString() + " DBType: " + myDBType;

    string resultScript;
    resultScript = "<script>parent.top.setStatusText('" + displayStatus + "');</script>";
    Page.RegisterClientScriptBlock("resultClientBlock",resultScript);

    SwitchDBType(intmid, permTempCheck, myDbType);
}

My button click events:

private void btnSwitchToType1_Click(object sender, Infragistics.WebUI.WebDataInput.ButtonEventArgs e)
{
    myDBType = "Type1";
}


private void btnSwitchToType2_Click(object sender, Infragistics.WebUI.WebDataInput.ButtonEventArgs e)
{
    myDBType = "Type2";
}

Thanks

Answer 1

You are missing:

if(!Page.isPostback)
{
   ...
}

This will make sure the Page_Load code you have there is only executed once.

I am not sure how or where you are getting intmid - you will probably need to put this line of code inside of the click events - but I am not sure so I just kept it in the Page_Load.

 SwitchDBType(intmid, permTempCheck, myDbType);

Full code will look like this:

private void Page_Load(object sender, System.EventArgs e)
{


     if(!Page.isPostback)
     {

         myDataSet = Session["myDataset"] as DataSet;

         if( myDataSet != null && myDataSet.Tables[0].Rows.Count > 0 )
         {
            myDBType = myDataSet.Tables[0].Rows[0]["dbType"].ToString();
         }
         else
         {
             myDBType = Connection.GetDBType(someid);
         }

         string displayStatus = "Value1: " + myID.Tables[0].Rows[0][0].ToString() +
             " Value2: " + myDataSet.Tables[0].Rows[0][1].ToString() +
             " Value3: " + myDataSet.Tables[0].Rows[0][5].ToString() + " DBType: " + myDBType;

         string resultScript;
         resultScript = "<script>parent.top.setStatusText('" + displayStatus + "');     </script>";
         Page.RegisterClientScriptBlock("resultClientBlock",resultScript);

         SwitchDBType(intmid, permTempCheck, myDbType);
    }
}

Answer 2

You don't need to trigger the event first. I suggest you extract your "business" logic into a method (that might even receive the DB type as a parameter). Then in the Page_Load you test whether this page load is a postback or not (ie occurred after a button click or not). If it's not a postback then you call the business logic method with a DB type from the session. If it's a postback then you do nothing in Page_Load , instead you change the two click handlers to call the business logic method with the appropriate DB type value.

Answer 3

if i understand you correctly, you cant get the click event to fire before the page load because of the page life cycle which you can read about here: http://msdn.microsoft.com/en-us/library/ms178472(v=vs.85).aspx

you can "cheat" by calling the event handler function from page init but thats not what you want....

Answer 4

You should place the code that loads the data based on the myDBType in the OnPreRender method. This method is called after the control events (your buttons click) is handled.