Building Dynamic Forms - ASP.NET Dynamic Data - page 391

protected void DynamicControl_Init(object sender, EventArgs e)
{
((UnleashedControl)sender).DataField = this.currentColumn.Name;
}
private PlaceHolder FindGroupPlaceHolder(MetaColumn column)
{
PlaceHolder placeHolder = null;
var display = column.Attributes.OfType<DisplayAttribute>().FirstOrDefault();
if (display != null && !string.IsNullOrWhiteSpace(display.GroupName))
placeHolder = (PlaceHolder)this.FindControl(display.GroupName);
return placeHolder ?? this.left;
}
}
}
The FindGroupPlaceHolder method tries to find a DisplayAttribute applied to the entity
property described by the MetaColumn object it receives. If the DisplayAttribute is found
and has the GroupName property specified, it calls the FindControl method inherited from
the ASP.NET's Control base class to find the PlaceHolder with the matching name. If the
entity property does not have a GroupName annotation or if the PlaceHolder with the speci-
fied name could not be found, the “ left ” PlaceHolder is returned by default. In other
words, unless you specify otherwise, the TwoColumn entity template displays controls on
the left side of the page.
Figure 11.8 shows how the Employee details page can look when the EntityUIHintAttribute
is applied to the entity class and the GroupName annotation is specified for the appropriate
entity properties.