/// <summary>
/// This method demonstrates how to undo the changes in Entities level using ObjectContext.
/// </summary>
public static void UndoChangesInEntities()
{
using (ObjectMySchool school = new ObjectMySchool())
{
ObjectDepartment department = school.ObjectDepartments.FirstOrDefault();
IQueryable <ObjectCourse> courses = from c in school.ObjectCourses
where c.DepartmentID == department.DepartmentID
select c;
Console.WriteLine("Before changes:");
foreach (ObjectCourse course in courses)
{
course.ShowObjectCourse();
}
// Change the department and the related course.
Console.WriteLine("After changes:");
department.Name += "-Modified";
foreach (ObjectCourse course in courses)
{
course.Title += "-Modified";
course.ShowObjectCourse();
}
Console.WriteLine("After Undo Course Entities:");
// Undo the ObjectCourse type Entities. We will see the changes of the department
// are not undone.
school.UndoObjectEntities <ObjectCourse>(school.ObjectCourses);
foreach (ObjectCourse course in courses)
{
course.ShowObjectCourse();
}
}
}
/// <summary>
/// This method demonstrates how to undo the changes in Entity level using ObjectContext.
/// </summary>
public static void UndoChangesInEnity()
{
using (ObjectMySchool school = new ObjectMySchool())
{
ObjectDepartment department = school.ObjectDepartments.FirstOrDefault();
IQueryable <ObjectCourse> courses = from c in school.ObjectCourses
where c.DepartmentID == department.DepartmentID
select c;
Console.WriteLine("Before changes:");
foreach (ObjectCourse course in courses)
{
course.ShowObjectCourse();
}
// Change the course.
Console.WriteLine("After changes:");
foreach (ObjectCourse course in courses)
{
course.Title += "-Modified";
course.ShowObjectCourse();
}
Console.WriteLine("After Undo the First Course Entity:");
// Undo one course. You can see only the changes of the first course are undone.
school.UndoObjectEntity(courses.FirstOrDefault());
foreach (ObjectCourse course in courses)
{
course.ShowObjectCourse();
}
}
}
/// <summary>
/// This method demonstrates how to undo the changes in Property level using ObjectContext.
/// </summary>
public static void UndoChangesInProperty()
{
using (ObjectMySchool school = new ObjectMySchool())
{
ObjectCourse course = school.ObjectCourses.FirstOrDefault();
ObjectDepartment department = school.ObjectDepartments.FirstOrDefault();
if (course != null)
{
Console.WriteLine("Before changes:");
course.ShowObjectCourse();
Console.WriteLine("After changes:");
// Change the course Properties.
course.Title += "-Modified";
course.Department = department;
course.ShowObjectCourse();
Console.WriteLine("After Undo Course Entity's Title Property:");
// Undo the change in the Entity Property level. UndoObjectEntityProperty
// method will undo the Title property of the course, but the change of the
// Department Property will not be undone.
school.UndoObjectEntityProperty(course, "Title");
course.ShowObjectCourse();
}
}
}
