delete database data using grid view button but returns me with null values

Question

This is how my gridview looks like:

enter image description here

I need to delete the selected row where there is a hidden column activityID and taskID which I set visible to false because I need their value to delete it from the database. I have to delete from database using QuestionNo , activityID and taskID .

ActivityID and TaskID is hidden , it actually looks like this :

QuestionNo,ActivtiyID,TaskID,QuestionContent then delete.

Code :

    protected void gvQuestion_RowCommand(object sender, GridViewCommandEventArgs e)
    {     


    }

    protected void gvQuestion_RowDeleted(object sender, GridViewDeletedEventArgs e)
    {

    }

    protected void LinkButton1_Click(object sender, EventArgs e)
    {


    }

    protected void gvQuestion_RowDeleting1(object sender, GridViewDeleteEventArgs e)
    {
        gvQuestion.DeleteRow(e.RowIndex);

         Model.question del = new Model.question();

        int q = Convert.ToInt32(gvQuestion.Rows[e.RowIndex].Cells[0].ToString());
        int a = Convert.ToInt32(gvQuestion.Rows[e.RowIndex].Cells[1].ToString()); // Hidden Column
        int t = Convert.ToInt32(gvQuestion.Rows[e.RowIndex].Cells[2].ToString()); // Hidden Column

        del.QuestionNo = q; 
        del.ActivityID = a;// Value of ActivityID column in GV
        del.TaskID = t; // Value of TaskID column in GV


        daoQuestion.Delete(del);
        daoQuestion.Save();
    }`

From what i know once delete button is pressed , it fires OnRowDeleting event so i put my delete codes in there , however i connection reset when i try to delete , the values of q , a , t is null , what gone wrong here? , The delete button is not working.. Help please , thanks . i am using EF to do this btw...

Here is the aspx :

 <asp:GridView ID="gvQuestion" runat="server"   
                AutoGenerateColumns="False" 
            onselectedindexchanged="gvQuestion_SelectedIndexChanged" 
            onrowcommand="gvQuestion_RowCommand" onrowdeleted="gvQuestion_RowDeleted" onrowdeleting="gvQuestion_RowDeleting1" 
             >
             <Columns>
                    <asp:BoundField DataField="QuestionNo" HeaderText="QuestionNo" 
                        InsertVisible="False" ReadOnly="True" SortExpression="QuestionNo" />
                    <asp:BoundField DataField="ActivityID" HeaderText="ActivityID" 
                        SortExpression="ActivityID" Visible="False" />
                    <asp:BoundField DataField="TaskID" HeaderText="TaskID" 
                        SortExpression="TaskID" Visible="False" />
                        <asp:BoundField DataField="joined" HeaderText="QuestionContent" 
                        SortExpression="joined" >
                    <ControlStyle Width="150px" />
                    </asp:BoundField>
                    <asp:TemplateField>
                        <ItemTemplate>
                        <span onclick="return confirm('Are you sure to Delete the record?')">
                            <asp:LinkButton ID="LinkButton1" runat="server" CommandName="Delete" 
                                onclick="LinkButton1_Click" CommandArgument="Delete">Delete</asp:LinkButton>
                        </ItemTemplate>
                    </asp:TemplateField>
                </Columns>
      </asp:GridView>

With data keys ( duno if this is the correct way ) :

aspx :

 DataKeyNames="QuestionNo,ActivityID,TaskID"

code behind :

  protected void gvQuestion_RowDeleting1(object sender, GridViewDeleteEventArgs e)
    {

        GridView gvQuestion = (GridView)sender;
        int row = e.RowIndex;

        int q = Convert.ToInt32(gvQuestion.DataKeys[row].Value[0].ToString());
        int a= Convert.ToInt32(gvQuestion.DataKeys[row].Value[1].ToString());
        int t = Convert.ToInt32(gvQuestion.DataKeys[row].Value[2].ToString()); // I assume that value 0 , 1 , 2 is according to the columns , not really sure on this.


 /*    Model.question del = new Model.question();
        del.QuestionNo = q; 
       del.ActivityID = a;// Value of ActivityID column in GV
        del.TaskID = t; // Value of TaskID column in GV


        daoQuestion.Delete(del);
      daoQuestion.Save();
      gvQuestion.DataBind(); */
    }

I am just trying to retrieve the values so i'll comment out the delete codes .. i check the values by debugging and returns 0 . is this the right way to do it?

I have edited your title. Please see, "Should questions include “tags” in their titles?", where the consensus is "no, they should not". — John Saunders
– John Saunders, Commented Jun 7, 2013 at 2:12
I will like to advise to set QuestionNo,ActivtiyID,TaskID as DataKey of Gridview. Check MSDN to know how to add multiple DataKey to GridView. Check How to use RowDeleting event of grid view using DataKey. Check Delete records in Gridview with multi-datakeynames in GridView. Hope you understand and works for you. — Rahul
– Rahul, Commented Jun 7, 2013 at 4:16

Michael Yoon · Accepted Answer · 2013-06-07 02:11:42Z

1

You are deleting a row, not selecting it, so selectedindex won't have anything, unless you've selected a row previously. You should use the information in the GridViewDeleteEventArgs. In there you can find the rowindex, as well as the data for columns you've marked as key columns.

answered Jun 7, 2013 at 2:11

Michael Yoon

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5 Comments

user2376998 Over a year ago

hi there , thanks for the reply . what do u mean by information in gridviewdeleteeventargs? .. and how can i retrieve info from there?

Michael Yoon Over a year ago

It's the second parameter in gvQuestion_RowDeleting1. You use it like any variable.

user2376998 Over a year ago

oh , sorry that i am new , i have updated my codes but i try to delete , the whole connection crashes.

user2376998 Over a year ago

this that the correct way to delete : int q = Convert.ToInt32(gvQuestion.Rows[e.RowIndex].Cells[0].ToString()); ?? because i need to get the value first before i could delete in database

user2376998 Over a year ago

the 3 statement returns Null and btw i converted boundfield to template field

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