Handling Concurrent Changes in LINQ

In a multi-user environment, there's a chance of concurrent updates to the same data by different users. In such cases, it's essential to handle concurrency conflicts to make sure data consistency is maintained. In this article, we'll look at how to handle concurrent changes in LINQ to ensure data integrity.

Syntax

DataContext.ConflictMode = ConflictMode.ContinueOnConflict;

Example

Let's consider a scenario where two users, A and B, are updating the same record in the database. User A retrieves the record from the database, modifies some data, and tries to save it to the database. Before the changes can be saved, User B also retrieves the same record, modifies some data, and saves it to the database. Now, when User A tries to save the changes, it'll result in a concurrency conflict, as the record has been modified by another user.

To handle this type of scenario, we can use the following code:

try
{
    DataContext.SubmitChanges();
}
catch (ChangeConflictException ex)
{
    DataContext.ChangeConflicts.ResolveAll(RefreshMode.KeepChanges);
    DataContext.SubmitChanges();
}

In the above code, we're using the ChangeConflictException exception to catch concurrency conflicts. We're then using the ResolveAll() method to accept the current changes and refresh the data from the database. Once the data is refreshed, we can then attempt to save changes to the database again using the SubmitChanges() method.

Output

The output of the above code will be the successful saving of the changes made by User A, even though the record was modified by User B in the meantime.

Explanation

In the above syntax, we set the ConflictMode property of DataContext to ContinueOnConflict to handle concurrency conflicts. When the SubmitChanges() method is called, it'll attempt to save all pending changes to the database. If there's a conflict, it'll throw a ChangeConflictException exception.

In the example above, we're catching the exception and resolving all conflicts by accepting the current changes and refreshing the data from the database. We're then attempting to save the changes to the database again.

Use

Handling concurrency conflicts is vital in multi-user environments to ensure data consistency and integrity. Using the ResolveAll() method, we can accept current changes and refresh the data from the database, resolving any concurrency conflicts that may exist.

Important Points

• Handling concurrency conflicts is essential in multi-user environments to ensure data consistency and integrity.
• Using the ChangeConflicts property of DataContext, we can resolve concurrency conflicts by accepting current changes and refreshing the data from the database.
• If there are any conflicts, SubmitChanges() will throw a ChangeConflictException exception.

Summary

In this article, we've looked at how to handle concurrent changes in LINQ to ensure data consistency and integrity. We've seen how to use the ResolveAll() method to accept current changes and refresh the data from the database, resolving any concurrency conflicts that may exist. Always handle concurrency conflicts in your LINQ applications to prevent data inconsistencies and ensure seamless application functionality.