Metadata API - ASP.NET Dynamic Data - page 195

The GetTable methods throws an ArgumentException if you specify a name or type of a
table that does not belong to the current MetaModel . In the unlikely scenario your code
expects to find non-existent tables, you can use the TryGetTable methods instead:
public bool TryGetTable(string uniqueTableName, out MetaTable table);
public bool TryGetTable(Type entityType, out MetaTable table);
The TryGetTable methods return a Boolean value that indicates whether or not the table
was found. The MetaTable itself is returned via the second output parameter. It will be
null if the method returns false . This follows a common .NET pattern and mimics the
TryGetValue method of the generic Dictionary class:
MetaTable table;
if (Global.DefaultModel.TryGetTable(“Products”, out table))
{
// use the table here …
}
Global Model Registration
By default, when a new MetaModel instance is created, it is registered globally, making it
available through the Default property of the MetaModel class as well as its GetModel
method. Both of them are static, thus making the model available to any page or control
in your web application:
public static MetaModel Default { get; }
public static MetaModel GetModel(Type contextType);
The Default property gives you an application-independent way to access the default
model, which you would normally get to via the DefaultModel property of the Global
class defined in Global.asax.cs . In other words, in a typical application, the following
lines of code produce the same result:
MetaModel model = Global.DefaultModel;
MetaModel model = MetaModel.Default;
When multiple data contexts have been registered with Dynamic Data, you can also use
the static GetModel method of the MetaModel class to retrieve a globally registered
MetaModel using its context type:
MetaModel model = MetaModel.GetModel(typeof(NorthwindEntities));
When using Dynamic Data in a large web application that interacts with multiple data-
bases and has multiple models, you might want to avoid global registration to reduce
chances of having different parts of the application affecting each other. For this purpose,
MetaModel class provides an overloaded constructor that takes a Boolean value as a para-
meter. Passing false to this constructor prevents the model from being globally registered:
public MetaModel(bool registerGlobally);