Pass additional variable to button_click() method

Question

I am creating a dynamic table for listing files.

It shows filename, filesize, dateModified columns. In addition, I have added one more columns: Delete.

The method which lists files of a folder in a table.

public void listFile()
{
    var dir = new DirectoryInfo(selectedFolder);

    Table fileTable = new Table();

    foreach (var file in dir.GetFiles())
    {
        TableRow tr = new TableRow();

        TableCell td1 = new TableCell();
        TableCell td2 = new TableCell();
        TableCell td3 = new TableCell();
        TableCell td4 = new TableCell();

        Label name = new Label();
        Label size = new Label();
        Label dateMod = new Label();
        LinkButton btn_delete = new LinkButton();

        name.Text = file.Name;
        size.Text = (file.Length / 1024) + " KB";
        dateMod.Text = file.LastWriteTime.ToLongTimeString();

        btn_delete.Text = "Delete";
        btn_delete.Click += new EventHandler(btn_delete_Click);

        td1.Controls.Add(name);
        td2.Controls.Add(size);
        td3.Controls.Add(dateMod);
        td4.Controls.Add(btn_delete);

        tr.Controls.Add(td1);
        tr.Controls.Add(td2);
        tr.Controls.Add(td3);
        tr.Controls.Add(td4);
    }

    filePanel.Controls.Add(fileTable);
}

protected void btn_delete_Click(object sender, EventArgs e)
{
    //Delete file
}

Now I want to delete the file when I click on the corresponding delete button. But problem is how will computer know which file to be deleted? I must pass the filename to the delete method.

Have you consider having a member variable holding the strings to the file then you can access that within the button — ZoomVirus
– ZoomVirus, Commented Sep 23, 2014 at 13:39
@zkanoca : Have you consider using a repeater instead of creating the table from code behind? — Arion
– Arion, Commented Sep 23, 2014 at 13:43
@zkanoca: Have a look at my answer. Hope it will help you to solve your problem. — HardikS
– HardikS, Commented Sep 23, 2014 at 13:59

HardikS · Accepted Answer · 2014-09-23 13:47:56Z

3

You can pass command argument to the link button as mentioned below:

btn_delete.CommandArgument =  [ID of the file]

and on click event of the link button you can access it as mentioned below:

protected void btn_delete_Click(object sender, EventArgs e)
{
    LinkButton btn = (LinkButton)sender;
    var id = btn.CommandArgument;
}

Reference: LinkButton.CommandArgument Property

answered Sep 23, 2014 at 13:47

HardikS

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Comments

Postlagerkarte · Accepted Answer · 2014-09-23 14:05:25Z

The answer from SpiderCode and RePierre about using the CommandArgument is a correct. It might however help you to understand that the CommandArgument is nothing more than a thin wrapper around the ViewState concept.

ViewState is one way how you can transport data between client and server. If you ever run into a similar problem and you don't have commandargument available you can resort to viewstate.

Take a look at the LinkButton.cs

public string CommandArgument {
            get {
                string s = (string)ViewState["CommandArgument"];
                return((s == null) ? String.Empty : s);
            }
            set {
                ViewState["CommandArgument"] = value;
            }

So you can either use the CommandArgument or use ViewState directly.

RePierre · Accepted Answer · 2014-09-23 13:48:41Z

1

You can use the CommandArgument property of btn_delete to pass the path to the file:

btn_delete.CommandArgument = file.Name;

And in the event handler you just have to get the value as following:

protected void btn_delete_click(object sender, EventArgs e)
{
    var button = sender as Button;
    var filename = button.CommandArgument;
}

answered Sep 23, 2014 at 13:48

RePierre

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Comments

Geno · Accepted Answer · 2014-09-23 13:42:16Z

-2

You can do this by creating a UserControl which is inheritated from the main Control. In my example I extended a Textbox with an address variable.

In that way you bind a value to the control, which you can use later.

public class ExtendedTextBox : System.Windows.Forms.TextBox
{
    private int? _Address = null;

    [Description("Address of variable")]
    [DefaultValue(null)]
    public int? Address
    {
        get { return _Address; }
        set { _Address = value; }
    }
}

answered Sep 23, 2014 at 13:42

Geno

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2 Comments

ZoomVirus Over a year ago

How does this fit in with their button press?

Geno Over a year ago

You should use the standard ButtonClickedEventHandler, So you can fetch the sender by the argument "sender".

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