Building Dynamic List Pages - ASP.NET Dynamic Data - page 445

Notice that the order of columns in the grid has been modified to make both the filter
and the grid column fit on the page without the user needing to scroll. This brings up an
important point you might want to consider when using custom properties along with the
metadata classes in your project. Here is a larger extract from the Product entity class,
which shows how the DisplayAttribute was applied to the ProductName and Country
properties to change their default order:
[MetadataType(typeof(Metadata))]
partial class Product
{
[Display(Order = 20)]
public string Country { get { return this.Supplier.Country; } }
private abstract class Metadata
{
[Display(Name = “Product Name”, Order = 10)]
public object ProductName { get; set; }
}
}
With entity classes generated automatically from the model definition by Entity
Framework or LINQ to SQL, you normally use a metadata class to specify data annota-
tions, such as the DisplayAttribute , for regular entity properties. The custom properties,
on the other hand, are created manually in the partial class, and you can apply data anno-
tations directly. Which approach is better?
In the example just given, placing the DisplayAttribute directly above the definition of
the Country property allows you to have all of its annotations in a single place (the UIHint
and FilterUIHint attributes are not shown to make the example shorter). However, it also
splits the information about the order of properties between the metadata class and the
entity class itself. Notice how the Country property appears first in the source file and
second in the dynamically generated web page. Alternatively, you could also consolidate
data annotations for all properties in the metadata class, as demonstrated in the next code
sample. While this approach brings the order of properties in the metadata class in sync
with their order on the dynamically generated pages, definition of the Country property is
now split between two different places:
[MetadataType(typeof(Metadata))]
partial class Product
{
public string Country { get { return this.Supplier.Country; } }
private abstract class Metadata
{
[Display(Name = “Product Name”, Order = 10)]
public object ProductName { get; set; }