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ASP.NET grid in 2.0 having trouble with paging to retain value of check box on save button click

Answer 1

+2 A:

First of all, let me restate the problem as I understand it. You have a paged Gridview that has checkboxes on it. You select some of the checkboxes, then move to a different page. When you come back to the original page, you want those checkboxes to still be checked.

There are two elements to doing this, saving the CheckBox state on the old page, and then setting the Checkbox state on the new page.

Saving the CheckBox state on the old page

For every row in the gridview, we need to examine the checkbox to see if it's checked. If it is checked, we record the data id (from DataKeys) into a List. If it isn't checked but it was previously, we remove that id from the list. After we've done this for every row, we save the list in Viewstate.

protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    List<int> selectedList;

    selectedList = (List<int>)this.ViewState["selectedList"];
    if (selectedList == null)
    {
        selectedList = new List<int>();
    }

    foreach (GridViewRow row in Gridview1.Rows)
    {
        if (row.RowType == DataControlRowType.DataRow)
        {
            CheckBox rowCheckBox;
            int rowId;

            // Get the Id
            rowId = (int)Gridview1.DataKeys[row.RowIndex].Value;

            // Get the CheckBox
            rowCheckBox = (CheckBox)row.FindControl("Chek");

            if (rowCheckBox.Checked)
            {
                // Don't add the id if it's already in the list
                if (selectedList.Contains(rowId))
                { }
                else
                {
                    selectedList.Add(rowId);
                }
            }
            else
            {
                // Remove the id if it was there but now we've unchecked the box
                if (selectedList.Contains(rowId))
                {
                    selectedList.Remove(rowId);
                }
            }
        }
    }

    // Save the list into viewstate
    this.ViewState["selectedList"] = selectedList;

    // Do the paging as normal
    GridView1.PageIndex = e.NewPageIndex;
    GridView1.DataSource = (DataTable)ViewState["dt"];
    GridView1.DataBind();
    GridView1.Visible = true;
    Btnsave.Visible = true;
}

Setting the CheckBox state on the new page

Now we're in a new page, as we databind each row we need to examine whether the Checkbox needs to be checked. To do this we will get the list out of Viewstate and as we bind each row we look to see if the key for the row is present in the list - if it is, we check the Checkbox. First off we need to attach this method to the Gridview:

<asp:GridView id="GridView1"  OnRowDataBound="Gridview1_RowDataBound" 
...

protected void Gridview1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    List<int> selectedList;
    int rowId;
    CheckBox rowCheckBox;

    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        selectedList = (List<int>)this.ViewState["selectedList"];

        if (selectedList == null)
        { }
        else
        {
            rowCheckBox = (CheckBox)e.Row.FindControl("Chek");

            // Get the id for the row
            rowId = (int)Gridview1.DataKeys[e.Row.RowIndex].Value;

            // If the row Id is in the list then check the CheckBox
            if (selectedList.Contains(rowId))
            {
                rowCheckBox.Checked = true;
            }
        }
    }
}

You should now be able to move between pages and your checkboxes will be persistent :-)

At the point where you click your Save button, I would guess that you want to remove the List from Viewstate (this.ViewState.Remove("selectedList")) so that you reset everything. The only other thing that youneed to be aware of here is that my demo code here is based on using a single field in DataKeyNames for the Gridview whereas you're using three fields, so you'll probably want to pick just one field to use for the list - I suspect studentId will do what you want e.g.

rowId = (int)Gridview1.DataKeys(row.RowIndex).Values["studentId"];

When you click your Save button, you need to get the list out of viewstate again, add any checked rows into it from the current page, and then use that to generate your datatable to pass to your manager object.

protected void Btnsave_Click(object sender, EventArgs e)
{
    List<int> selectedList;

    selectedList = (List<int>)this.ViewState["selectedList"];
    if (selectedList == null)
    {
        selectedList = new List<int>();
    }

    foreach (GridViewRow row in Gridview1.Rows)
    {
        if (row.RowType == DataControlRowType.DataRow)
        {
            CheckBox rowCheckBox;
            int rowId;

            // Get the Id
            rowId = (int)Gridview1.DataKeys[row.RowIndex].Value;

            // Get the CheckBox
            rowCheckBox = (CheckBox)row.FindControl("Chek");

            if (rowCheckBox.Checked)
            {
                // Don't add the id if it's already in the list
                if (selectedList.Contains(rowId))
                { }
                else
                {
                    selectedList.Add(rowId);
                }
            }
            else
            {
                // Remove the id if it was there but now we've unchecked the box
                if (selectedList.Contains(rowId))
                {
                    selectedList.Remove(rowId);
                }
            }
        }
    }

    int passoutYear = Convert.ToInt32(passout.SelectedValue);
    int companyId = Convert.ToInt32(company.SelectedValue);
    int courseId = Convert.ToInt32(course.SelectedValue);
    string package = txtpackage.Text.Trim();
    string venu = txtvenue.Text.Trim();

    DateTimeFormatInfo dateInfo = new DateTimeFormatInfo();
    dateInfo.ShortDatePattern = "dd/MM/yyyy";
    DateTime date = Convert.ToDateTime(vistDate.Text.Trim(), dateInfo);

    DataTable gridviewTbl = new DataTable();
    ...

    foreach (int id in selectedList)
    {
        DataRow newStudentRow;
        newStudentRow = gridviewTbl.NewRow;
        newStudentRow[0] = id;
        newStudentRow[1] = courseid;
        ...
        gridviewTbl.Rows.Add(newStudentRow);
    }

    if (gridviewTbl.Rows.Count != 0)
    {
        Boolean b = placedStudentManager.SaveSelectdStudent(gridviewTbl);
        if (b)
        {
            gridNotExist.Text = "Records Successfully inserted";
        }
    }
    else
    {
        gridNotExist.Text = "Please check the record to be inserted";
        Btnsave.Visible = true;
        GridView1.Visible = true;
    }
}

PhilPursglove 2010-09-01 15:01:46

Thanks for your response i was looking for this solution for long back. I appreciate you response. Well i have achieved the state for check box while paging in grid view. Your's way is also immaculate and worth praising. But sir i need one more help in this now on save button on button click a want all those checked rows to be set in database how should i do that and my misery is that if i take checked rows in temp datatable and then some body revert back to previous page and unchecked the check box how will i reflect it t data table. Would you please enlighten me on this as well

NoviceToDotNet 2010-09-01 17:19:22

Please rid me off from remaining predicament that of saving checked rows of grid-view to be inserted in to database i did it in this way have a glance but remaining it yet to do..

NoviceToDotNet 2010-09-01 17:21:56

protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e) { Response.Write(GridView1.PageIndex.ToString()); int d = GridView1.PageCount; bool[] values = new bool[GridView1.PageSize]; CheckBox chb; for (int i = 0; i < GridView1.Rows.Count; i++) { chb = (CheckBox)GridView1.Rows[i].FindControl("Chek"); if (chb != null) { values[i] = chb.Checked; } }

NoviceToDotNet 2010-09-01 17:24:27

i dont know how to edit this :- remaing down side Session["page" + GridView1.PageIndex] = values; GridView1.PageIndex = e.NewPageIndex; GridView1.DataSource = (DataTable)ViewState["dt"]; GridView1.DataBind(); GridView1.Visible = true; Btnsave.Visible = true;}

NoviceToDotNet 2010-09-01 17:24:52

to be continued:- protected void GridView1_PreRender(object sender, EventArgs e) { if (Session["page" + GridView1.PageIndex] != null) { CheckBox chb; bool[] values = (bool[])Session["page" + GridView1.PageIndex]; for (int i = 0; i < GridView1.Rows.Count; i++) { chb = (CheckBox)GridView1.Rows[i].FindControl("Chek"); chb.Checked = values[i]; } } }

NoviceToDotNet 2010-09-01 17:25:40

please edit this sir all above comment or please let me know how do edit this sort of comment ..............u nicely edited every thing.if any key to be press fr this like CTR+D then please let me know

NoviceToDotNet 2010-09-01 17:26:56

@NoviceToDotNet Can you edit your question and add all that code into the bottom of your question please.

PhilPursglove 2010-09-01 22:39:01

@PhilPursglove:- I have added my solution to the above my existing asked question .....

NoviceToDotNet 2010-09-03 06:35:30

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ASP.NET grid in 2.0 having trouble with paging to retain value of check box on save button click

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