Re: Object reference not set to an instance of an object - ASP.NET Discussion Boards

how to call back from server side

Piyush Vardhan Singh
p_vardhan14@rediffmail.com
http://holyschoolofvaranasi.blogspot.com
http://holytravelsofvaranasi.blogspot.com

I have no idea what you mean, but I'd guess that it's not possible. Your server side creates html which is sent to the client when the client requests it. The client side does not exist while the server side is running.

Christian Graus

Please read this if you don't understand the answer I've given you

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

Soposed that i have two aspx page One have hash table and another page have data grid
when hash tabele add new data in table then it inform to another page u refresh ur grid

Piyush Vardhan Singh
p_vardhan14@rediffmail.com
http://holyschoolofvaranasi.blogspot.com
http://holytravelsofvaranasi.blogspot.com

Are both forms visible at once ? If so, then if they are not parent and child, I doubt you can do that, without polling using AJAX. If only one is visible at a time then the form will work out the new state for itself as it reloads.

Christian Graus

Please read this if you don't understand the answer I've given you

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

Hi
In my webform(webform1.aspx), i have an iFrame control, along with with many web controls.
The "src" attribute of it refers to another webform.(webform2.aspx)

I want text to appear in the frame on clicking a button which fetches the
value from db. Am using a session variable to hold the text to be assigned for iframe.

And am using the following code in WebForm1.aspx

<br />
private void Button1_Click(object sender, System.EventArgs e)<br />
{<br />
 Session["Cont"]		=	"This is a page";<br />
 <br />
HtmlGenericControl	frame1	=	(HtmlGenericControl)this.FindControl("txtFrame");<br />
<br />
 frame1.Attributes["src"]	=	"WebForm2.aspx";		<br />
<br />
 Server.Execute("WebForm2.aspx");<br />
 Response.ClearContent();<br />
}<br />

And in WebForm2.aspx,Page_Load(..)

<br />
if(Session["Cont"]!=null)<br />
{<br />
	Literal1.Text	=	Session["Cont"].ToString();<br />
}<br />

The problem is when i click the button in WebForm1.aspx, along with actual text, a textbox with some characters is appearing in the iFrame though there's no other control in the target(Webform2.aspx) other than Literal control. Frown | :(

Please help me in finding out the actual problem and its solution.
Thanks

~VSree

Hi,

I have this code for my e-Commerce site (asp.net2 with C#) for adding items to Shopping Cart:

protected void btnAddToCart_Click(object sender, ImageClickEventArgs e)
{
string Price = double.Parse(((Label)DataList1.Controls[0].FindControl("PriceLabel")).Text).ToString("0.00");
string ProductName = ((Label)DataList1.Controls[0].FindControl("BookNameLabel")).Text;
string PictureURL = ((Label)DataList1.Controls[0].FindControl("picLabel")).Text;
int ProductID = Convert.ToInt32(Request.QueryString["idLabel"]);
if (Profile.cart == null)
{
Profile.cart = new ShopCart.myshoppingcart();
}
Profile.cart.Insert(ProductID,Convert.ToDouble(Price),1,ProductName,PictureURL);
Server.Transfer("ItemIndex.aspx");
}

but when i'm runnig my site and click on btnAddToCart
this error occur:
Object reference not set to an instance of an object.
i underlined my code where this error occur.

i search in google but i didn't get any result or i don't underestand what should i do?

how i can solve this error?

thank you,

Hoda

Saba02 wrote:
string Price = double.Parse(((Label)DataList1.Controls[0].FindControl("PriceLabel")).Text).ToString("0.00");

Wow - what horrible code.

Try this:

if (DataList1.Controls.Length > 0)
{
Control c = DataList1.Controls[0];
Label l = c.FindControl("PriceLabel") as Label;
if (l != null)
{
string Price = l.Text;

Apart from the layers of code with no error checking, what on earth possesses you to do a double.Parse, then turn it back to a string ? If you want to make sure the value is a double, use double.TryParse, not a method that, if it fails, throws an exception.

Christian Graus

Please read this if you don't understand the answer I've given you

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

This is quite a general error message.
You will need to check that all code referenced in the c# is correct at time of processing:
i.e. dont refer to a control in c# which doesnt exist in aspx page
For example you could be finding a control that doesnt exist or

Saba02 wrote:
QueryString["idLabel"]);

the above might not exist or be transferring

Can you post your aspx?

Hello all,
In a data table in am getting number of rows present is dataset returned by query.If my datatable contain 15 rows the i want to remove last 5 rows.I need only 10 rows in datatable and bind that rows to datalist.
So how can i remove additional rows (more than 10) from data table.

<br />
QuestionCount =0<br />
 QuestionCount = QuestionCount + questionDs.Tables(0)<br />

Please help me.