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DataContext.GetChangeSet Method

.NET Framework 4.5

Gets the modified objects tracked by DataContext.

Namespace: System.Data.Linq
Assembly: System.Data.Linq (in System.Data.Linq.dll)

public ChangeSet GetChangeSet()

Return Value

Type: System.Data.Linq.ChangeSet
The set of objects is returned as three read-only collections.

Remarks

Note the following considerations:

GetChangeSet might have side effects, such as inference of insert and delete operations that are usually performed at the time of SubmitChanges. For example, objects that are used in the following operations can create corresponding inferred operations in the following list:
- Add to InsertOnSubmit.
- EntityRef<TEntity> assignment to null (possibly because of Remove to DeleteOnSubmit.
The set may not be ordered according to foreign key constraints.
Database-generated values (for example, primary and foreign key values, timestamps, and so forth) are not available. Such information requires database command execution and perhaps the propagation of retrieved information (for example, foreign key from primary key).
The set of changed objects is computed at the time of the call. Subsequent calls to SubmitChanges can produce a different set if additional changes are made.

Output when no changes have been made appears as follows:

{Added: 0, Removed: 0, Modified: 0}

Examples

Northwnd db = new Northwnd(@"c:\northwnd.mdf");

var custQuery =
    from cust in db.Customers
    where cust.City == "London" 
    select cust;

foreach (Customer custObj in custQuery)
{
    Console.WriteLine("CustomerID: {0}", custObj.CustomerID);
    Console.WriteLine("\tOriginal value: {0}", custObj.City);
    custObj.City = "Paris";
    Console.WriteLine("\tUpdated value: {0}", custObj.City);
}

ChangeSet cs = db.GetChangeSet();
Console.Write("Total changes: {0}", cs);
// Freeze the console window.
Console.ReadLine();

db.SubmitChanges();

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4

Platforms

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

DataContext Class

System.Data.Linq Namespace

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