LINQ to SQL - updating records

Question

Using asp.net 4 though C#.

In my data access layer I have methods for saving and updating records. Saving is easy enough but the updating is tedious.

I previously used SubSonic which was great as it had active record and knew that if I loaded a record, changed a few entries and then saved it again, it recognised it as an update and didn't try to save a new entry in the DB.

I don't know how to do the same thing in LINQ. As a result my workflow is like this:

1. Web page grabs 'Record A' from the DB
2. Some values in it are changed by the user.
3. 'Record A' is passed back to the data access layer
4. I now need to load Record A again, calling it 'SavedRecord A', update all values in this object with the values from the passed 'Record A' and then update/ save 'SavedRecord A'!

If I just save 'Record A' I end up with a new entry in the DB.

Obviously it would be nicer to just pass Record A and do something like:

RecordA.Update();

I'm presuming there's something I'm missing here but I can't find a straightforward answer on-line.

Answer 1

You can accomplish what you want using the Attach method on the Table instance, and committing via the SubmitChanges() method on the DataContext.

This process may not be as straight-forward as we would like, but you can read David DeWinter's LINQ to SQL: Updating Entities for a more in depth explanation/tutorial.