Function not working on <%# %> expression

Question

We are localizing a webpart for Sharepoint 2013, and we will use a specific function to translate the terms (so we can switch from a database backed-up translation table to a resource and vice-versa).

For the html elements we are successfully using this, and it's working like a charm:

<td><%= MyNameSpace.MySubNameSpace.StaticClass.GetTranslation("My Text") %>:</td>

But for the asp controls the text is not working properly, although it compiles ok:

<asp:CheckBox ID="myCheckBox" runat="server" Checked="True" Text='<%# MyNameSpace.MySubNameSpace.StaticClass.GetTranslation("My Text") %>' />

The MyNameSpace.MySubNameSpace.StaticClass is static, as well as the GetTranslation function.

Any clue on this?

EDIT: There is a way I can write a function that loop all the asp controls, get their current text value and change it by passing it through my translation function? Something like this:

...
foreach(AspControl _control in WebPart.Controls)
{
    if (_control.typeof() == <Control with Text properties>)
        _control.Text = MyNameSpace.MySubNameSpace.StaticClass.GetTranslation(_control.Text);
}
...

Answer 1

The <%# %> syntax in ASP.NET is only valid in a databinding context, such as in <ItemTemplate> containers of the ListView control, or on controls for which you explicitly call the DataBind() function.

Similarly frustrating, in this scenario, is that the <%= %> syntax corresponds to literal output, and cannot be used to assign values to control properties.

If you are committed to the course of using the <asp:CheckBox /> control, then I recommend setting the properties in a script block during the PreRender event. It would look something like this:

<script runat="server">
    protected override void OnPreRender(EventArgs e)
    {
        this.myCheckBox.Text = Namespace.Class.GetTranslation("My Text");
        base.OnPreRender(e);
    }
</script>

Note that if you have a code-behind class, you can omit the script tags and put the method in your code-behind.

Perhaps more elegant would be exploring whether the <asp:FormView /> meets your needs. It provides a container for a single databound object, and can support databinding syntax (<%# %>) within its various templates.

Answer 2

You can use HTML tag instead of <asp:CheckBox

<input ID="myCheckBox" Checked="True" type="checkbox" />
<label><%# MyNameSpace.MySubNameSpace.StaticClass.GetTranslation("My Text") %></label>