You add the following method to an application that uses LINQ to SQL:
public Person LookupStudent(intstudentId)
{
using (var dataContext = new SchoolDataClassesDataContext())
{
return dataContext.Persons.FirstOrDefault(p =>p.PersonID == studentId);
}
}
You find that the following code throws an exception when attempting to iterate the child entities given by the StudentGrades property:
var student = LookupStudent(studentId);
foreach (var g in student.StudentGrades)
{
//
}
You need to modify the LookupStudent method to fix the exception.
What should you do?

The C# using (Using in Visual Basic) statement provides a convenient syntax that ensures the correct use of IDisposable objects. The using statement calls the Dispose method on the object when program execution exits the using block. When you are relying on lazy loading, you cannot dispose of the data context before properties are lazy loaded. The entity objects will require the data context to lazy load properties. To fix the exception, you can remove the using to not dispose and allow the data context to be disposed when the related objects are garbage collected. Alternatively, you can explicitly load the child property before disposing of the data context.