Create link button in code behind, to make it call another method in code behind

Question

I have been looking for a way to create a link in my code behind which will call a method in my code behind with its ID as parameter. It is basicly a getting content from the database and show it, then being able to delete a row if needed. This is my code:

    protected void showDBContent(object sender, EventArgs e)
{
    String queryString = "";
    if (showDBDropDown.Text == "Show all")
    {
        queryString = "SELECT * from dbo.Search";
    }
    else
    {
        queryString = "SELECT * from dbo.Search where Tag = '" + (showDBDropDown.Text).TrimStart().TrimEnd() + "'";
    }
    List<String> tags = new List<String>();
    List<String> urls = new List<String>();
    using (SqlConnection conn = new SqlConnection(info.connectionString))
    using (var cmd = conn.CreateCommand())
    {
        conn.Open();
        cmd.CommandText = queryString;
        using (SqlDataReader reader = cmd.ExecuteReader())
        {
            while (reader.Read())
            {
                tags.Add(reader.GetString(0));
                urls.Add(reader.GetString(1));
            }
        }
    }
    HtmlTable tempTable = showDBTable;
    int i = 0;
    foreach (String tag in tags)
    {
        String url = urls[i];
        HtmlTableRow row = new HtmlTableRow();
        HtmlTableCell cell1 = new HtmlTableCell();
        HtmlTableCell cell2 = new HtmlTableCell();
        HtmlTableCell cell3 = new HtmlTableCell();
        LinkButton link = new LinkButton();
        link.Click += new EventHandler(DeleteRow);
        link.Text = "Delete";
        link.ID = "deleteRow" + i;

        cell3.Controls.Add(link);
        row.Cells.Add(cell3);
        cell1.InnerText = tag;
        row.Cells.Add(cell1);
        cell2.InnerText = url;
        row.Cells.Add(cell2);
        tempTable.Rows.Add(row);
        i++;
    }
}
protected void DeleteRow(object sender, EventArgs e)
{

}

However it if never getting in the method DeleteRow. Any clues?

Answer 1

Your code is kind of messy - you need to clean it up a little.

First of all, instead of using a <table> element you'd be better by using a GridView and bind data to it using DataSource property.

After that, you can add a TemplateField to your grid view columns. In that template you can declare the link button:

<asp:GridView runat="server" ID="gridView" OnRowDataBound="OnGridRowDataBound">
    <Columns>
        ...
        <TemplateField>
            <ItemTemplate>
                <asp:LinkButton runat="server" ID="linkButton" Click+="OnDeleteButtonClick"/>
            </ItemTemplate>
        </TemplateField>
    <Columns>
</asp:GridView>

Then, in the handler for OnRowDataBound event of the GridView set the CommandArgument of the LinkButton to the value of row identifier:

protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    var button = e.NamingContainer.FindControl("linkButton") as LinkButton;
    button.CommandArgument = e.Row.RowIndex;
}

Now, when user clicks on your LinkButton all you have to do is to parse the CommandArgument (and then of course, use it as your application logic dictates):

protected void OnDeleteButtonClick(object sender, EventArgs e)
{
    var button = sender as LinkButton;
    int rowIndex = int.Parse(button.CommandArgument);
    // Delete the row with index rowIndex.
}

Answer 2

try this instead.

foreach (String tag in tags)
        {
            String urls[i];
            HtmlTableRow row = new HtmlTableRow();
            HtmlTableCell cell1 = new HtmlTableCell();
            HtmlTableCell cell2 = new HtmlTableCell();
            HtmlTableCell cell3 = new HtmlTableCell();
            LinkButton link = new LinkButton();
            link.Text = "Delete";
            link.ID = "deleteRow" + i;

            cell3.Controls.Add(link);
            ((LinkButton)(cell3.Controls[0])).Click += Delete_Click;
            row.Cells.Add(cell3);

            cell1.InnerText = tag;
            row.Cells.Add(cell1);
            cell2.InnerText = url;
            row.Cells.Add(cell2);
            tempTable.Rows.Add(row);
            i++;
        }

    protected void Delete_Click(object sender, EventArgs e)
    {
        //throw new NotImplementedException();
    }