Скачать или смотреть How to Use Validate :on with Custom Methods in Rails Controllers

Learn how to implement custom validations in Rails models for specific controller actions while maintaining clean architecture.
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Understanding Custom Validations in Rails

When you're building APIs with Ruby on Rails, it's crucial to ensure that the data you receive and manipulate is valid. This means implementing models that validate business rules effectively. A common challenge arises when you want to run custom validation checks in specific situations, such as inside a custom controller method. This guide dives into how to resolve such challenges and streamline your validation processes.

The Problem: Running Custom Validations

In the scenario presented, a Rails application needs to perform a PUT or PATCH request to a specific route that invokes a custom method (update_premium) in the BarsController. The main concern is to ensure that a validation check in the model runs correctly when calling save or valid?, particularly for the update_premium action.

Here’s the relevant portion of the Bar model:

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The method runs validations effectively when using the standard on: :update but does not trigger properly for on: :update_premium.

The Solution: Adjusting Your Validations

To resolve this issue, consider the following adjustments to your validation logic in the Bar model. The goal is to allow validations to run for the intended scope without creating unnecessary complications.

Preferred Approach: Run Validation Always

Instead of tying your validation logic to specific contexts (on: :create or on: :update_premium), you can simplify your validation method:

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By doing this:

Validation will occur every time you call valid? or save, ensuring robust validation logic.

You maintain flexibility since you will consistently check for your custom validation conditions.

Alternative Approach: Conditional Updates

If separating your validations is necessary for business logic, consider the following:

Keep the Validation for Updates: You can still use a standard update method and check your custom conditions there.

Manual Validity Check: Explicitly trigger a validation check by calling valid? after performing relevant attribute updates.

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Conclusion

By implementing these strategies, you can efficiently manage custom validations in your Rails models and keep your controller logic clean. Remember that valid? will run all validations. This approach can save time debugging and maintain the integrity of your application's data.

In summary, you have two paths:

Generalize validation to run at all times, ensuring all data integrity checks are enforced.

Create conditional checks within your controller for selective validation, if absolutely necessary.

By adopting these practices, you'll streamline your Rails app's validation mechanics while adhering to DRY principles.