C# grid view with delete link button , values returns NULL when retrieve values to be deleted

Question

0.00/5 (No votes)

See more:

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 , GridView actually looks like this :

QuestionNo,ActivtiyID,TaskID,QuestionContent , deletebutton

My aspx codes , i have converted the columns to templatefield from boundfield and i keep getting null values when trying to retrieve the values of the columns ( for example: QuestionNo , ActivityID and TaskID .What exactly is the correct way to do this? i am using Entitiy Framework to do this.

My Code looks like this :

C#

protected void Page_Load(object sender, EventArgs e)
       {
           if (!Page.IsPostBack)
           {
               BindQuestions();


           }
       }

       protected void BindQuestions()
       {
            gvQuestion.DataSource = daoQuestion.GetList();
            gvQuestion.DataBind();
       }

       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();
       }`

Posted 6-Jun-13 19:39pm

jyan32193

Updated 6-Jun-13 20:59pm

v2

Add a Solution

Comments

jyan32193 7-Jun-13 1:44am

i tried using datakeys as well , values are still null , i already converted boundfield to templatefield

Rabbil 7-Jun-13 1:57am

Are you getting the respective values on the variables ??

jyan32193 7-Jun-13 2:07am

nope i am not getting any values , they all returns me 0 value . am i retrieving correctly?

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Rabbil · Answer 1 · 2013-06-06T19:55:00

Solution 1

For deletion operation using Ado.net Entity framework...
Try using..

C#

daoQuestion.Attach(del);///Firstly, Attach the entity object to context
DeleteObject(del); ///specifies the object to delete
SaveChanges();

Posted 6-Jun-13 19:55pm

Rabbil

Comments

jyan32193 7-Jun-13 2:08am

no such definition for attach and , the problem is i need to retrieve the values first in order to delete them based on their values ID .. but the values are returning me 0

Rabbil 7-Jun-13 2:27am

In what controls are you binding the data in gridview ?
You can try using
int q = ((yourControlnametoCast)GVOptions.Rows[0].FindControl("controlNameOfQinYourGrid")).Text.Trim(); ///this will find the value from the respective control of your grid
after above line
del.QuestionNo = q; ///now check once again whether u are getting the value or not.... ?

jyan32193 7-Jun-13 2:37am

sorry i am new to c# , i didn't use any controls to bind data , i populate the grid view using entity data source .

Rabbil 7-Jun-13 2:51am

Then it will return null value only....
Better,you can refer here for you overall requirement.. http://techbrij.com/insert-update-delete-gridview-entity-framework

jyan32193 7-Jun-13 3:01am

i have updated the codes above if u're referring to how i get my gridview data , duno if its wad u want to see

Rabbil 7-Jun-13 3:09am

Yeah,if you have modified & still not getting the values while debugging then you can refer the shared link to further modify your code to achieve your goal...As you have not used any controls so that link may help you if you can get your result.

uspatel · Answer 2 · 2013-06-06T20:14:00

You can use RowCommand event for deleting row from gridview
use as

ASP.NET

<asp:LinkButton ID="l1" runat="server" Text="Remove" %>'  CommandName="Remove"  CommandArgument='<%#Eval("id") %>'></asp:LinkButton>

and on rowcommand event

C#

void GVDetail_RowCommand_RowCommand(Object sender, GridViewCommandEventArgs e)
{
if(e.CommandName=="Remove")
{
GridViewRow row = (GridViewRow)(((LinkButton)e.CommandSource).NamingContainer);
            int index = row.RowIndex;
            string id=row.Cells[0].Text;//this will retrive column 1 value     
//var id = Int32.Parse(e.CommandArgument);
     GVDetail.DeleteRow(int.Parse(id));
GVDetail.DataBind();


 }
}