Eval Method with link button

Question

2.50/5 (2 votes)

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C#

<td align="center">
                               <asp:LinkButton ID="LinkButton4" PostBackUrl='<%# "~/ProductCatalog.aspx?ID="+Eval("ProductID") %>' runat="server"><5000</asp:LinkButton>
                           </td>

Eval method is not working with a link button.. what is the problem

on products catalog page

C#

string query = "Select * from Products where ProductID= '" + Request.QueryString["ID"].ToString() + "' AND UnitCost < 5000";
        //DataSet ds = new DataSet();
        DataSet ds=obj.fillgrid(query);
        GridView1.DataSource = ds.Tables[0];
        GridView1.DataBind(); ;

i am getting error on that page that object referenc not set to instance of an object

Posted 24-Dec-11 8:37am

codegeekalpha

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Nigam Patel 26-Dec-11 22:40pm

can you please past you code behind file code ? and if possible then also past you whole query so i have idea what is your problem?

2 solutions

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NandaKumer · Answer 1 · 2011-12-24T10:21:00

Solution 2

check this blog
http://stackoverflow.com/questions/2637330/databinder-eval-in-c-sharp[^]
--NDK

Posted 24-Dec-11 10:21am

NandaKumer

Monjurul Habib · Answer 2 · 2011-12-24T08:45:00

Solution 1

Try following:

XML

<asp:LinkButton ID="LinkButton1" PostBackUrl='<%# String.Format("ProductCatalog.aspx?ID={0}",Eval("ProductID")) %>' runat="server"><5000</asp:LinkButton>

In addition if your ProductID data type is int then you need to use the following code:

C#

if(Request.QueryString["ID"]!="" && Request.QueryString["ID"]!=null){
string query = "Select * from Products where ProductID= " +Convert.ToInt32(Request.QueryString["ID"].ToString()) + " AND UnitCost < 5000";
}

UPDATED
*********************************

Assign this property at server side :

C#

LinkButton4.PostBackUrl = "ProductCatalog.aspx?ID=" + ProductID;

OR
Replace LinkButton by HyperLink as LinkButtons were originally designed to do a postback .

C#

<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# Eval("ProductID", "ProductCatalog.aspx?ID={0}") %>'></asp:HyperLink>

Let me know your result.

Posted 24-Dec-11 8:45am

Monjurul Habib

Updated 24-Dec-11 9:34am

v4

Comments

codegeekalpha 24-Dec-11 15:21pm

nothing happenend.. page is even not redirected to product catalog.aspx

Monjurul Habib 24-Dec-11 15:35pm

try my updated section and let me know

Monjurul Habib 24-Dec-11 15:36pm

try: <asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# Eval("ProductID", "ProductCatalog.aspx?ID={0}") %>'>

codegeekalpha 24-Dec-11 15:43pm

hyperlink is not acting like a link.. its just a text i used this

<td align="center">
<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# Eval("ProductID", "ProductCatalog.aspx?ID={0}") %>'>HyperLink
</td>

Monjurul Habib 24-Dec-11 15:56pm

Try on code behind: HyperLink1.NavigateUrl="~/ProductCatalog.aspx?ID=" +ProductID+ "";

codegeekalpha 24-Dec-11 15:58pm

code behind me.. in C#? or in Aspx

codegeekalpha 24-Dec-11 16:00pm

i put that in page load and getting productId is not found in current context

Monjurul Habib 24-Dec-11 16:05pm

share your code behind (.cs file code)

codegeekalpha 24-Dec-11 16:09pm

protected void Page_Load(object sender, EventArgs e)
{
HyperLink1.NavigateUrl="~/ProductCatalog.aspx?ID=" +ProductID+ "";

} i have only this code.. do i need to get the data from database for <%# Eval("ProductID", "ProductCatalog.aspx?ID={0}") %>'>HyperLink

Monjurul Habib 24-Dec-11 16:12pm

yes, you need to write code for getting "ProductID" from database.

codegeekalpha 24-Dec-11 16:16pm

can u tell me how.. for gridview i wrote the code like this .. string query="Select CategoryID,CategoryName from Categories";
DataSet ds=obj.fillgrid(query);
GridView1.DataSource = ds.Tables[0];
GridView1.DataBind();
what i have to write for to have productid in linkbutton link button

codegeekalpha 24-Dec-11 16:26pm

hello pls tell me.??

Monjurul Habib 24-Dec-11 16:31pm

TELL ME WHAT IS YOUR PROBLEM ACTUALLY?? How to bind GridView?? This is the basic, you need to do some homework.

NandaKumer 25-Dec-11 10:54am

nice answer