Asp.NET Font-Size and service function - asp.net

Question

i've the following code in aspx page
<asp:Label ID="CittaLabel" runat="server" Text='<%# Eval("Citta") %>' Font-Size='<%# ReturnFontSize(Eval("Big")) %>'/>
and this is my code behind service function
Protected Function ReturnFontSize(ByVal Big As Boolean) As FontUnit
If Big Then
ReturnFontSize = FontSize.Medium
Else
ReturnFontSize = FontSize.Small
End If
End Function
But i get always a font very very small.
So my question is : for changing "Font-Size" proprety of a control, from code behind, which return type i have to use, assuming that FontUnit not work ?
Thank you

Answer 1

You have to DataBind the Containercontrol of the label(f.e. a GridView or the complete page). Then you can call a Codebehind Function from the aspx-page.
Hence f.e. in Page-Load:
Me.DataBind()
and the function must return an object from type FontSize:
Protected Function ReturnFontSize(ByVal fontSize As Object) As FontSize
Select Case fontSize.ToString.ToUpper
Case "BIG"
Return WebControls.FontSize.Large
Case Else
Return WebControls.FontSize.Medium
End Select
End Function
and on aspx-page:
Font-Size='<%# ReturnFontSize(Eval("Big")) %>'
But why dont you set the Fontsize in Codebehind on Page.Load?
Me.CittaLabel.FontSize= ....

Answer 2

I find that performing Eval based property setting during a databinding event can often prove problematic unless you are binding to simple types such as strings and ints. It's generally easier and to simply perform your complex binding tasks during the code behind implementation of binding events such as the Repeater databind event.
Try the following instead, assuming you are using an ASP:Repeater control:
Markup:
<asp:Repeater runat="server" ID="rpt" OnDataBinding="rpt_OnDataBinding">
<ItemTemplate>
<asp:Label ID="CittaLabel" runat="server" Text='<%# Eval("Citta") %>' />
</li>
</ItemTemplate>
</asp:Repeater>
Code Behind:
protected void rpt_DataBinding(object sender, RepeaterItemEventArgs e)
{
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
{
var data = (YourTypeThatIsDataBound)e.Item.DataItem;
var CittaLabel = (Label)e.Item.FindControl("CittaLabel");
CittaLabel.FontSize = ReturnFontSize(data.Big);
}
}
This way for every item being generated in your repeater you access the label in the server side databinding event and simply set the FontSize to be the output of your ReturnFontSize function that you have alread written. The only thing you have to do is cast the e.Item.DataItem object back to the original type of object the repeater was bound to and then pass its Big property into the function.