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The Strongly Typed DataContext

The final aspect of the sqlmetal.exe-generated code to be aware of is the DataContext-derived type.

Like the AutoLotDatabase class we authored in the previous example, each table is represented by a

Table-compatible property. As well, this class has a series of constructors, one of which takes an

object implementing IDbConnection, which represents an ADO.NET connection object (remember,

LINQ to SQL and ADO.NET types can be intermixed within a single application).

As well, this DataContext-derived class is how we are able to interact with the stored procedures

defined by the database. Given the fact that we supplied the /sprocs flag as part of our sqlmetal.exe

command set, we find a method named GetPetName():

[Function(Name="dbo.GetPetName")]

[return: Parameter(DbType="Int")]

public int GetPetName([Parameter(DbType="Int")] System.Nullable carID,

[Parameter(DbType="Char(10)")] ref string petName)

{

IExecuteResult result = this.ExecuteMethodCall(this,

((MethodInfo)(MethodInfo.GetCurrentMethod())), carID, petName);

petName = ((string)(result.GetParameterValue(1)));

return ((int)(result.ReturnValue));

}

Notice that the GetPetName() method is marked with the [Function] attributes and [return:]

attribute qualifier, while each parameter is marked with the [Parameter] attribute. The implemen-

tation makes use of the inherited ExecuteMethodCall() method (and a bit of reflection services) to

take care of the details of invoking the stored proc and returning the result to the caller.