.NET Framework Class Library
DataContext..::.ObjectTrackingEnabled Property

Instructs the framework to track the original value and object identity for this DataContext.

Namespace:  System.Data.Linq
Assembly:  System.Data.Linq (in System.Data.Linq.dll)
Syntax
Visual Basic (Declaration) 
Public Property ObjectTrackingEnabled As Boolean
Visual Basic (Usage) 
Dim instance As DataContext
Dim value As Boolean

value = instance.ObjectTrackingEnabled

instance.ObjectTrackingEnabled = value
C# 
public bool ObjectTrackingEnabled { get; set; }
Visual C++ 
public:
property bool ObjectTrackingEnabled {
    bool get ();
    void set (bool value);
}
JScript 
public function get ObjectTrackingEnabled () : boolean
public function set ObjectTrackingEnabled (value : boolean)

Property Value

Type: System..::.Boolean
true to enable object tracking; otherwise, false. The default is true.
Remarks

Setting this property to false improves performance at retrieval time, because there are fewer items to track.

An exception is thrown:

  • If the property is set to false after a query has been executed.

    For more information, see the Valid Modes section in DataContext.

  • If the property is set to false and SubmitChanges is called.

If ObjectTrackingEnabled is false, DeferredLoadingEnabled is ignored and treated as false. In this case, the DataContext is read-only.

If ObjectTrackingEnabled is true, DeferredLoadingEnabled is false. In this case, DataContext allows you to load an object graph by using LoadWith directives, but does not enable deferred loading.

TopicLocation
How to: Retrieve Information As Read-OnlyLINQ to SQL
How to: Retrieve Information As Read-OnlyLINQ to SQL
Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
Version Information

.NET Framework

Supported in: 3.5
See Also

Reference

DataContext Class
DataContext Members
System.Data.Linq Namespace
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Community Content

Ayman Ali
ObjectTrackingEnabled = True and WCF
Tags :

Ayman Ali
ObjectTrackingEnabled = True and WCF
Usually in a SOA model, you will have a service operation that retrieves the data to send it back to the client and then destroys the datacontext and forgets about the client all together.
Without the original datacontext or the original data you can not really track changes. That’s to say you can not move this data across tiers or layers and expect to track changes unless you pass the data context as well, the client should maintain the reference to the data context and send it back with the request for update. In other words, Your data context with ObjectTrackingEnabled = True must be kept alive until the data comes back modified in order for object tracking to work.
Since, The DataContext class is not designed to survive across layers and tiers. You should think of it as a sort of database connection object—to grab as late as possible and release as soon as possible. Entities queried through a given context remain bound to that context for eternity—when object tracking is enabled. You can’t attach an external entity object to a data context different from the one which created the entity.

Cached data remains available even after the data context has been disposed of. What if you modify this data in memory and then want to save changes back to the database? To submit changes to the SQL Server table, you still need a data context object. You have a few options:

1- Caching the original data context,
2- Implementing the data context as a singleton
3- Use a fresh instance of the data context class.

The DataContext class is not designed for being thread safe. So any use of it that configures usage from within different threads is not recommended.

The DataContext class is designed to be a short-lived, lightweight object that you use and dispose of as soon as possible. Yes, it is much like an ADO.NET database connection object.


Using a fresh instance is definitely the way to go. to use a fresh instance the client should send the original data as well as the modified data to the service. When the service receives both original data and modified data, the original data need to be attached to a fresh context and then the modified data updated into the context.

if your original data is in a List called OriginalData
and your modified data is in a list called ModifiedData
and your table is called MyTable
and your primay key is called Primary key
if the data context is declared as dc

then you can use a line like this to implement the attach and update of the modified data

OriginalData.ForEach(p=> dc.MyTable.Attach(ModifiedData.Where(x=> x.PrimaryKey == p. PrimaryKey).First(), p ));
You can get the modified object by simply calling
dc.MyTable.Context.GetChangeSet().Updates
To get the deleted objects
dc.MyTable.Context.GetChangeSet().Deletes
Inserted objects
dc.MyTable.Context.GetChangeSet().Inserts


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