Chapter 5. Validating your Data: Preventing mistakes
Everyone makes mistakes... but many of them are preventable! Even with the very best of intentions, your users will still enter bad data into your web app, leaving you to deal with the consequences. But just imagine if there was some way of preventing mistakes from happening in the first place. Thatâs where validators come in. Keep reading, and weâll show you how to add clever Rails validation to your web app so that you can take control of what data is allowed inâand what needs to be kept out.
Watch outâthereâs bad data in the room
Everything seemed to be going so well with the personal trainersâ web app, at least until the body builders showed up. The body builders say theyâve paid their gym dues, and have the receipts to prove it, but their payments arenât showing up on the system.
So what went wrong?
Clicking on the save button should have saved the data into the database, but something went wrong. Instead of saving the amount paid as $50, the amount got saved as 0.0. But how? Letâs take a look at the chain of events that occurred.
A trainer enters â$50â into the paid field in the view, and then clicks on the save button. A value of â$50â is passed to the controller.
The controller receives a value of â$50â ...
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