Databases Reference
In-Depth Information
custom properties and enable most of the rich template scaffolding for displaying and
filtering them. In this section, you see how this can be accomplished.
Model Providers
The provider API is defined in the
System.Web.DynamicData.ModelProviders
namespace.
At the high-level, it consists of the four classes shown in Figure 13.5—
DataModelProvider
,
TableProvider
,
ColumnProvider
, and
AssociationProvider
. The
DataModelProvider
class
provides the information required to construct a
MetaModel
object consumed by a
Dynamic Data application. For instance, it includes a property called
Tables
, which
returns a collection of
TableProvider
objects. Each
TableProvider
encapsulates a single
entity class and provides all information necessary to construct a
MetaTable
object. In
particular, it has a property called
Columns
that returns a collection of
ColumnProvider
objects that
MetaTable
uses to construct
MetaColumn
instances. Unlike the metadata API,
where the
MetaColumn
class has two descendants,
MetaForeignKeyColumn
and
MetaChildrenColumn
, that represent navigation properties (such as the
Supplier
property
of the Product entity), the provider API uses a separate class called
AssociationProvider
.
FIGURE 13.5
Metadata providers.
Dynamic Data comes with several built-in model providers, including providers for the
Entity Framework and LINQ to SQL. Each model provider includes a set of four classes,
each inheriting from the corresponding provider base class and overriding the required
virtual methods and properties. Knowledge of the built-in model providers is hard-coded
in the
MetaModel
class, which allows you to register both Entity Framework
ObjectContext
types and LINQ to SQL
DataContext
types by calling the same
RegisterContext
method,
which takes
Type
as a parameter. However, the
MetaModel
class also defines an overloaded
version of the
RegisterContext
method that takes a
DataModelProvider
as a parameter
and that enables you to create custom providers for other LINQ-enabled frameworks and
use them with Dynamic Data.
