See what changes will be done to the DB before saving an import in Rails 2.3
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I have an import/export from/to xls of my Products, SubProducts & Costs of my DB. The thing is an importation can make big changes on the DB. That's why I need to add one step: the preview of the changes and a confirm link.

I have no idea how I could "simulate" the import, log the differences, NOT save changes yet and wait for the user's confirmation.

Can somebody help me on this?

(Rails 2.3.11, PostGreSQL)