An easy way to keep deleted data in your database.
"Soft delete" in database lingo means that you set a flag on an existing table which indicates that a record has been deleted, instead of actually deleting the record.
If you create a new date column (the column type will depend on your database vendor, but usually you want to use date, datetime, or timestamp) on a table and name it deletedAt, Wheels will automagically start using it to record soft deletes.
Without the soft delete in place, a delete() call on an object will delete the record from the table using a DELETE statement. With the soft delete in place, an UPDATE statement is sent instead (that sets the deletedAt field to the current time).
Of course, all other Wheels functions are smart enough to respect this. So if you use a findAll() function, for example, it will not return any record that has a value set in the deletedAt field.
What this all means is that you're given a convenient way to keep deleted data in your database forever, while having your application function as if the data is not there.
Occasionally you might want to include data which has been flagged for deletion. You can do this easily by adding includeSoftDeletes=true to any findAll type call.
Obviously, if you have any manual queries in your application, you'll need to remember to add deletedAt IS NULL to the WHERE part of your SQL statements instead.