Add asp:Button from codebehind

I’m building a in codebehind. The table is a listing of a database records (one record per row) and I neeed to add a delete button for each row. To do that, I of course need to build a button with a unique ID for that. To do that, I came up with the following … which doesn’t work. Any tips on how to get this working?

Button deleteButton = new Button();
deleteButton.ID = "deleteStudentWithID" + singleStudent.ID.ToString();
deleteButton.Text = "X";

string row = "<tr>";
row += "<td class="style5">"+deleteButton.ClientID +"</td>";
row += "</tr>";

Answers:

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Method 1

Your problem is that you’re adding only the ClientID of your control to the html and not adding the control to the page itself.

Controls.Add(new LiteralControl("<table>"));

foreach(var singleStudent in students)
{
    Controls.Add(new LiteralControl("<tr>"));

    //Code to add other columns

    Button deleteButton = new Button();
    deleteButton.ID = "deleteStudentWithID" + singleStudent.ID.ToString();
    deleteButton.Text = "X";

    Controls.Add(new LiteralControl("<td class="style5">"));
    Controls.Add(deleteButton);
    Controls.Add(new LiteralControl("</td></tr>");
}

Controls.Add(new LiteralControl("</table>"));

Method 2

Instead of creating the entire table markup in your code behind, use the controls made available by ASP.NET.

For an example, place this in your .aspx:

<table>
    <asp:Repeater runat="server" ID="MyRepeater1">
        <ItemTemplate>
            <tr>
                <td><%# Eval("StudentName")%></td>
                <td>... other student object bindings ...</td>
                <td>
                    <asp:Button runat="server" ID="MyDeleteButton"
                            CommandArgument='<%# Eval("ID")%>'
                            CommandName="Delete"
                            OnCommand="MyDeleteButton_Command"
                            Text="X" />
                </td>
            </tr>
        </ItemTemplate>
    </asp:Repeater>
</table>

And include this in your code-behind:

protected void Page_Load(object sender, EventArgs e)
{
    MyRepeater1.DataSource = new MyStudent[]
        {
            new MyStudent()
                {
                    ID = 1,
                    StudentName = "Student 1"
                },
            new MyStudent()
                {
                    ID = 2,
                    StudentName = "Student 2"
                }
        };
    MyRepeater1.DataBind();
}

protected void MyDeleteButton_Command(object sender, CommandEventArgs e)
{
    switch (e.CommandName)
    {
        case "Delete":
            // stuff for deleting by e.CommandArgument
            break;
    }
}

Method 3

The best Solution to Your problem i can think of is

Button deleteButton = new Button();
deleteButton.ID = "deleteStudentWithID" + singleStudent.ID.ToString();
deleteButton.Text = "X";

StringBuilder sb = new StringBuilder();
StringWriter writer = new StringWriter(sb);
HtmlTextWriter htmlWriter = new HtmlTextWriter(writer);
deletedButton.RenderControl(htmlWriter);

string row = "<tr>";
row += "<td class="style5">"+sb.toString(); +"</td>";
row += "</tr>";

This way you can get any control’s HTML. 🙂 If you are building dynamically HTML from code behind then try not to use string rather StringBuilder. strings are immutable and has performance penalty.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0