Question

After postback (click on a button) in my ASP.NET form, all the DataItem of my form are null. Why? What should I do to retrieve the content of the DataList even after postback?

protected void buttonAddRecord_Click(object sender, EventArgs e)
    {
        foreach (DataListItem item in listFields.Items)
        {
            // item.DataItem == null  WTF?
        }
    }

protected void Page_Load(object sender, EventArgs e)
    {
        BindFields();
    }

private void BindFields()
    {
        object setting = MySettings.GetSetting();

        if (!Null.IsNull(setting))
        {
            listFields.DataSource =     
                DataProvider.GetData(int.Parse(setting.ToString()));
            listFields.DataBind();
        }

        listFields.Visible = listFields.Items.Count > 0;
        emptyMessage.Visible = listFields.Items.Count == 0;
    }

Answer 1

Found my answer here.

What John said, the data source items
are only avaliable when databound.
They are no longer accessable after
initial loading.

You might consider having an object or
object collection representing
onscreen data that you update with the
grid, then persist changes from that
to databases.

More precisely, I used an HiddenField to store an ID across posts and I request data from the database instead of trying to get it form the DataItem (which can’t be used outside the databinding event).

The HiddenField control is used to
store a value that needs to be
persisted across posts to the server.