/// <summary>
/// Demostrate how to update POCO entity properties with change
/// tracking proxy.
/// </summary>
private static void UpdatePropertyWithChangeTrackingProxy()
{
Console.WriteLine("Update properties with change tracking proxy...");
try
{
using (POCOChangeTrackingEntities context =
new POCOChangeTrackingEntities())
{
Department department = context.Departments.
Single(d => d.Name == "Chinese");
// Retrieve the entity state entry.
ObjectStateEntry entry = context.ObjectStateManager.
GetObjectStateEntry(department);
// It should be "Unchanged" now.
Console.WriteLine("Entity State before modification: {0}",
entry.State);
department.Name = "New Department Name";
// It should be "Modified" now.
Console.WriteLine("Entity State after modification: {0}",
entry.State);
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
/// <summary>
/// Demostrate how to update POCO entity relationships without change
/// tracking proxy.
/// </summary>
private static void UpdateRelationshipWithoutChangeTrackingProxy()
{
Console.WriteLine("Update relationships without change tracking proxy...");
try
{
using (POCOChangeTrackingEntities context =
new POCOChangeTrackingEntities())
{
// Turn off proxy creation.
context.ContextOptions.ProxyCreationEnabled = false;
Department department = context.Departments.
Single(d => d.Name == "Chinese");
// Create a regular POCO entity.
Course newCourse = new Course()
{
CourseID = 1234,
Title = "Classical Chinese Literature",
Credits = 4,
StatusID = true
};
// Set the relationship.
department.Courses.Add(newCourse);
Console.WriteLine("Is the newly created object a proxy? {0}",
IsProxy(newCourse));
// Retrieve all the newly added entities' object state entry before
// DetectChanges is called.
var addedBeforeDetectChanges = context.ObjectStateManager.
GetObjectStateEntries(EntityState.Added);
// It should be no entity added.
Console.WriteLine("Before DetectChanges is called, " +
"{0} object(s) added", addedBeforeDetectChanges.Count());
// Detect the entity relationships modification.
context.DetectChanges();
// Retrieve all the newly added entities' object state entry after
// DetectChanges is called.
var addedAftereDetectChanges = context.ObjectStateManager.
GetObjectStateEntries(EntityState.Added);
// It should be 1 entity added.
Console.WriteLine("After DetectChanges is called, " +
"{0} object(s) added", addedAftereDetectChanges.Count());
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
/// <summary>
/// Demostrate how to update POCO entity properties without change
/// tracking proxy.
/// </summary>
private static void UpdatePropertyWithoutChangeTrackingProxy()
{
Console.WriteLine("Update properties without change tracking proxy...");
try
{
using (POCOChangeTrackingEntities context =
new POCOChangeTrackingEntities())
{
// Turn off proxy creation.
context.ContextOptions.ProxyCreationEnabled = false;
Department department = context.Departments.
Single(d => d.Name == "Chinese");
// Retrieve the entity state entry.
ObjectStateEntry entry = context.ObjectStateManager.
GetObjectStateEntry(department);
// It should be "Unchanged" now.
Console.WriteLine("Entity State before modification: {0}",
entry.State);
department.Name = "New Department Name";
// It should be "Unchanged" now.
Console.WriteLine("Entity State after modification: {0}",
entry.State);
// Detect the entity properties changes.
context.DetectChanges();
// It should be "Modified" now.
Console.WriteLine("Entity State after DetectChanges is called: "
+ "{0}", entry.State);
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
/// <summary>
/// Demostrate how to update POCO entity relationships with change
/// tracking proxy.
/// </summary>
private static void UpdateRelationshipWithChangeTrackingProxy()
{
Console.WriteLine("Update relationships with change tracking proxy...");
try
{
using (POCOChangeTrackingEntities context =
new POCOChangeTrackingEntities())
{
Department department = context.Departments.
Single(d => d.Name == "Chinese");
// Create a proxy object.
Course newCourse = context.Courses.CreateObject();
newCourse.CourseID = 1234;
newCourse.Title = "Classical Chinese Literature";
newCourse.Credits = 4;
newCourse.StatusID = true;
// Set the relationship.
department.Courses.Add(newCourse);
Console.WriteLine("Is the newly created object a proxy? {0}",
IsProxy(newCourse));
// Retrieve all the newly added entities' object state entry.
var added = context.ObjectStateManager.GetObjectStateEntries(
System.Data.EntityState.Added);
Console.WriteLine("{0} object(s) added", added.Count());
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
