A couple of, I hope Basic Questions RE SqlDataSources and scripting

Greetings!

I am writing a proof of concept ASP.net application for my employer and I have run into a couple perplexing issues. First off, In my Page_Load event I have the following code.

txOTHrs.Attributes[

"onBlur"] ="return calculateTotal(this)";

The onblur event handler is coded as follows

function calculateTotal(tb)

{

var regHrs = document.getElementById ("txRegHrs").value; var otHrs = document.getElementById("txOtHrs").value; var rate = document.getElementById("txRate").value; var regAmt = rate * regHrs; var otAmt= rate * ( otHrs * 1.5 ); var total = otAmt + regAmt;

document.getElementById(

"txTotal").value = total;

}

Everything seems to work fine. The onBlur event is handled and, as I expect the value in the txTotal text box is updated correctly. The problem occurs when I try to access that value in the codebehind page. When ever I look at txTotal.Text in the debugger it is always blank. This has left me scratching my head as I can clearly see a value on the web page. Have I missed some step where I have to notify the server that a value in the control has changed ?

My second question is, I hope a very easy one to answer. In WinForms when I have a dataset I can access the individual rows ( in an untyped dataset ) by speficying dataset.tables["tableName"].Rows[index]. Is there any similar mechanism for accessing the individual rows, and fields in the SqlDataSource object in ASP.net ?

Any help anyone can provide is greatly appreciated!!

If you are comming from a "Windows Forms" world, then there are a few key concepts that you are going to need to understand... most especially is the "Page Lifecycle" which I will mention further down... but to answer your questions quickly:

sabrecat:

Have I missed some step where I have to notify the server that a value in the control has changed ?

- Yes... you need to "PostBack" to the server at any time that you want to reflect changes.

sabrecat:

In WinForms when I have a dataset I can access the individual rows ( in an untyped dataset ) by speficying dataset.tables["tableName"].Rows[index]. Is there any similar mechanism for accessing the individual rows, and fields in the SqlDataSource object in ASP.net ?

- Again, Yes... here is a small example:

DataView myDataView = (DataView)this.MarketDataSource.Select(DataSourceSelectArguments.Empty);

foreach (DataRow rowin myDataView.Table.Rows)
{
// do something here :)
}

// Or you can do...

string firstPersonsLastName = (string)myDataView.Table.Rows[0]["LastName"];

Here is the "Page Lifecycle" that I mentioned earlier:
http://msdn2.microsoft.com/en-us/library/ms178472.aspx
http://www.eggheadcafe.com/articles/o_aspNet_Page_LifeCycle.jpg

Read the MSDN article, save that picture to your desktop and look at it often :)

I hope this helps.

Peace,

|||

Thank you very much for the reply! You have been tremendously helpful!

I thought that the data that I was putting into the control wasnt getting back to the serve. I wasnt sure what mechanism to use however to get it into the server. To actually perform thepostback I would use the __doPostBack function that ASP.Net puts into the page right ? I mean in my script I'd do somthing like

function calculateTotal(e, tb)
{
var regHrs = document.getElementById ("txRegHrs").value;
var otHrs = document.getElementById("txOtHrs").value;
var rate = document.getElementById("txRate").value;
var regAmt = rate * regHrs;
var otAmt= rate * ( otHrs * 1.5 );
var total = otAmt + regAmt;
document.getElementById("txTotal").value = total;
__doPostBack(tb,e);
}

Since my calulateTotal function right now only has the one argument (tb) I assume then that I would have to change my codebehind page to look somthing like

txOTHrs.Attributes[

"onBlur"] ="return calculateTotal(event, this)";

instead of

txOTHrs.Attributes["onBlur"] ="return calculateTotal(this)";

Regarding the SqlDataSource. Does the argument DataSourceSelectArguments.Empty make the invocation of the Select method NOT go out to the database again ? If this is not the case and the database is hit again then I would want to get the data into a DataView at the time that I do my initial select on the database and then put that object into the session to make it persistant between page reloads ?

Again thank you very much for all the insights and the links to some really good data.

508 Compliance?

Do you definitely need scripting enabled for anything to work in RS 2005?.

We have a govt client..so basically if the answer is not, we cannot use RS2005.

thanks.

If you are using the Web Interface, you will need scripting enabled for your browser. The Winforms control does not require scripting enabled on the client.