Building Dynamic Forms - ASP.NET Dynamic Data - page 377

field.HeaderText = column.ShortDisplayName;
else
field.HeaderText = column.Prompt ?? column.DisplayName;
field.ItemStyle.Wrap = false;
return field;
}
}
}
The UnleashedFieldGenerator provides a parameterized constructor, which is required to
specify the MetaTable object when the generator is created. It also overrides the
CreateField method to create and initialize a new instance of the UnleashedField
control. In particular, it sets the HeaderText property of the new field using different
values from the column metadata, depending on the context where the new field will be
used. If List value was passed as the containerType , it means that the field will appear in
a GridView control and the short version of column's display name is used as the header.
Otherwise, if Item container type was specified, the field will appear in a DetailsView
control and the prompt (if it was specified) or the full display name of the column will be
displayed in the label. Finally, wrapping is turned off to prevent validators from appearing
on the next line if an error needs to be reported by the field template.
With the UnleashedFieldGenerator class, you still have to modify the List and
ListDetails page templates to use it. In custom pages, where you initialize the
ColumnsGenerator property of GridView control explicitly, you can simply change the
code to instantiate the UnleashedFieldGenerator explicitly. However, in the dynamic
page templates that come with the Dynamic Data project in Visual Studio, the
DefaultAutoFieldGenerator is created by the DynamicDataManager during the
InitComplete event of the Page . To replace this logic, you can create your own
Page.InitComplete event handler as shown in this code snippet:
public partial class List : System.Web.UI.Page
{
protected MetaTable table;
protected void Page_InitComplete(object sender, EventArgs e)
{
this.gridView.ColumnsGenerator = new UnleashedFieldGenerator(this.table);
}
}
Because the Page_InitComplete method runs after the event handler the
DynamicDataManager uses to initialize the ColumnsGenerator property of the GridView , this
code replaces it with the UnleashedFieldGenerator . As a result, the GridView will be
populated with UnleashedField instances that have full support for metadata-driven
control parameters, and the Address text box, for which the Columns parameter was speci-
fied in metadata of the Employee entity, will now be wide enough to support longer
address values.