Gridview overwrites rows

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Using this example, I have a problem.
I have a gridview:

ASP

<asp:GridView ID="GridView1" runat="server"
                                ShowFooter="True" AutoGenerateColumns="False" Width="100%" Height="100%">
                                <Columns>
                                    <asp:BoundField DataField="RowNumber" HeaderText="Nr.">
                                        <ControlStyle BorderStyle="None" />
                                    </asp:BoundField>
                                    <asp:TemplateField HeaderText="Message">
                                        <ItemTemplate>
                                            <asp:TextBox Native="True" ID="txtName" runat="server"></asp:TextBox>
                                        </ItemTemplate>
                                        <ControlStyle BorderStyle="None" />
                                    </asp:TemplateField>
                                    <asp:TemplateField HeaderText="Data">
                                        <ItemTemplate>
                                            <asp:TextBox ID="txtAge" runat="server"></asp:TextBox>
                                        </ItemTemplate>
                                        <ControlStyle BorderStyle="None" />
                                    </asp:TemplateField>

                                </Columns>
                            </asp:GridView>

and 2 buttons. When I click each button, a new row is inserted in Gridview. To create and bind data tot GridView, I have 2 functions:

C#

private void AddNewRow(string s, string s1)
        {
            int rowIndex = 0;

            if (ViewState["CurrentTable"] != null)
            {

                DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
                DataRow drCurrentRow = null;
                if (dtCurrentTable.Rows.Count > 0)
                {
                    for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
                    {
                        TextBox TextBoxName =
                          (TextBox)GridView1.Rows[rowIndex].Cells[1].FindControl("txtName");
                        TextBoxName.Text = s;
                        TextBox TextBoxAge =
                          (TextBox)GridView1.Rows[rowIndex].Cells[2].FindControl("txtAge");
                        TextBoxAge.Text = s1;

                        drCurrentRow = dtCurrentTable.NewRow();
                        drCurrentRow["RowNumber"] = i + 1;

                        dtCurrentTable.Rows[i - 1]["Col1"] = TextBoxName.Text;
                        dtCurrentTable.Rows[i -1]["Col2"] = TextBoxAge.Text;

                        rowIndex++;
                    }
                    dtCurrentTable.Rows.Add(drCurrentRow);
                    ViewState["CurrentTable"] = dtCurrentTable;

                    GridView1.DataSource = dtCurrentTable;
                    GridView1.DataBind();
                }
            }
            else
            {
                Response.Write("ViewState is null");
            }
            SetPreviousData();
        }

        private void SetPreviousData()
        {
            int rowIndex = 0;
            if (ViewState["CurrentTable"] != null)
            {
                DataTable dt = (DataTable)ViewState["CurrentTable"];
                if (dt.Rows.Count > 0)
                {
                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        TextBox TextBoxName = (TextBox)GridView1.Rows[rowIndex].Cells[1].FindControl("txtName");
                        TextBox TextBoxAge = (TextBox)GridView1.Rows[rowIndex].Cells[2].FindControl("txtAge");


                        TextBoxName.Text = dt.Rows[i]["Col1"].ToString();
                        TextBoxAge.Text = dt.Rows[i]["Col2"].ToString();

                        rowIndex++;
                    }
                }
            }
        }

When I click on button 1, data is bound and a new row is created:

C#

protected void Button1_Click(object sender, EventArgs e)
        {   DateTime data = DateTime.Now;
            string dt = data.ToString();
            AddNewRow("Start", dt);
         }

When I click on button 2, data is bound and a new row is created:

C#

>protected void Button2_Click(object sender, EventArgs e)
        {   DateTime data = DateTime.Now;
            string dt = data.ToString();
            AddNewRow("Stop", dt);
         }

Let's say that first I click on button 1. Everything is ok. First row contains the message "Start" and the corresponding date. Also a new row is created. If I press button 2, row 2 contains the message "Stop" and the corresponding date, but also first row is overwritten with the message "Stop". What should I do to don't overwrite the first row?

What I have tried:

What I tried is already shown.

Posted 20-Nov-19 1:56am

DrgIonuţ

Updated 20-Nov-19 4:57am

Herman<T>.Instance

v3

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Comments

Herman<T>.Instance 20-Nov-19 7:57am

I guess the problem is the viewstate. It is set once and resued. I do not see any code where the ViewState is updated after adding a row.

DrgIonuţ 20-Nov-19 8:06am

Ok. But a new row is added with the text from button 2. The problem is that row 1 is updated with the message from row 2.

Herman<T>.Instance 20-Nov-19 8:08am

Yeah but the first new row is not added to the viewstate, so you add the second row to the original viewstate. If you put a breakpoint @ DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"]; you will see....

DrgIonuţ 20-Nov-19 8:27am

To see what? Nothing seems to be wrong.

CHill60 20-Nov-19 7:58am

If you use the debugger and step into your AddNewRow function you will see that you are going into the loop that sets every row in your datatable to the text passed it.

DrgIonuţ 20-Nov-19 8:03am

If I comment "dtCurrentTable.Rows[i - 1]["Col1"] = TextBoxName.Text;
dtCurrentTable.Rows[i -1]["Col2"] = TextBoxAge.Text;", no text is displayed. What should I do?

CHill60 20-Nov-19 8:11am

Don't just comment lines of code out randomly!
I don't know why you have chosen to overwrite all the existing rows with those values but if I just wanted to add a new row I would create a new row, populate that row with my data (this is the bit you are missing), then add that row to the datasource, then rebind.

DrgIonuţ 20-Nov-19 8:16am

I don't want to overwrite the previous row. This is why I put the question. Something has to be changed in my code in order to don't overwrite, but I don't know what...

Richard MacCutchan 20-Nov-19 8:50am

Maybe if you post your question in the forum at the end of the article referenced in your question, the author will have some suggestions.

DrgIonuţ 20-Nov-19 9:01am

I did, but I was hopping to be something simple to change in my code.

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CHill60 · Answer 1 · 2019-11-20T04:58:00

Solution 1

Try something like the following (caveat - untested)

C#

DataRow drCurrentRow = dtCurrentTable.NewRow();
drCurrentRow["Col1"] = s;
drCurrentRow["Col2"] = s1;
dtCurrentTable.Rows.Add(drCurrentRow);

Posted 20-Nov-19 4:58am

CHill60

Comments

DrgIonuţ 21-Nov-19 3:02am

Thank you for your reply, CHill60!
My AddNewRow function now looks like:
private void AddNewRow(string strg, string strg1)
{
DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
DataRow drCurrentRow = null;

drCurrentRow = dtCurrentTable.NewRow();
drCurrentRow["Col1"] = strg;
drCurrentRow["Col2"] = strg1;
dtCurrentTable.Rows.Add(drCurrentRow);
ViewState["CurrentTable"] = dtCurrentTable;
GridView1.DataSource = dtCurrentTable;
GridView1.DataBind();
}
A new row is added, but the text doesn't appear. I also have tried to replace "strg" and "strg1" with "ab" and "cd", but the result is the same.

CHill60 21-Nov-19 3:56am

try drCurrentRow["Message"].Value = s etc. Use the debugger to check that the DataTable is correctly populated and you are using the correct column names. If that is ok then it's the databinding or the way you have set up your gridview.
I'm sorry - I don't have Visual Studio here at the moment so I can't debug your code

DrgIonuţ 21-Nov-19 4:16am

"Value" property doesn't exist. Thanks! :)