C# 4 and .NET 4

872 ❘ ChaPTer 31 AdO.net entity frAmewOrk
public BooksEntities(EntityConnection connection) : base(connection, "BooksEntities")
{
this.ContextOptions.LazyLoadingEnabled = true;
OnContextCreated();
}
partial void OnContextCreated();
public ObjectSet Authors
{
get
{
if ((_Authors == null))
{
_Authors = base.CreateObjectSet("Authors");
}
return _Authors;
}
}
private ObjectSet _Authors;
}
public ObjectSet Books
{
get
{
if ((_Books == null))
{
_Books = base.CreateObjectSet("Books");
}
return _Books;
}
}
private ObjectSet _Books;
code snippet BooksDemo/BooksModel.Designer.cs
The ObjectContext class provides several services to the caller:
➤ It keeps track of entity objects that are already retrieved. If the object is queried again, it is taken from
the object context.
➤ It keeps state information about the entities. You can get information about added, modified, and
deleted objects.
➤ You can update the entities from the object context to write the changes to the underlying store.
Methods and properties of the ObjectContext class are listed in the following table.
objeCTConTeXT meThods
and ProPerTies
Connection
MetadataWorkspace
QueryTimeout
ObjectStateManager
desCriPTion
Returns a DbConnection object that is associated with the
object context.
Returns a MetadataWorkspace object that can be used to read the
metadata and mapping information.
With this property you can get and set the timeout value for the
queries of the object context.
This property returns an ObjectStateManager. The
ObjectStateManager keeps track of entity objects retrieved and
object changes in the object context.
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