What is the difference between `update` and `update_attributes`?

In Rails, both update and update_attributes are used for updating records in the database, but they offer distinct functionalities and use cases. Understanding these differences helps in writing more efficient and accurate Rails applications.

Understanding update

The update method is a powerful feature in Rails that allows you to change one or more attributes of a record. It instantly saves the changes to the database and is commonly used when you are certain of the changes being valid.

1user = User.find(1)
2user.update(name: 'John Doe', email: 'john.doe@example.com')
3

In this example, the user object's name and email are updated simultaneously, and these changes are committed to the database immediately.

Key Features of update

• Atomic Operation: The update method saves records directly without needing an explicit save call.
• Validations: Perform model-level validations and return false if any validation fails.
• Callbacks: Initiate callbacks like before_update and after_update, allowing additional logic to run during the update process.

Understanding update_attributes

The update_attributes function operates similarly to update, but it provides more extensive handling of attributes, particularly beneficial in older versions of Rails. It also performs validations and persists the changes to the database if validations pass.

1user = User.find(1)
2user.update_attributes(name: 'Jane Doe', email: 'jane.doe@example.com')
3

Key Features of update_attributes

• Legacy Support: update_attributes has been more commonly used in legacy Rails applications.
• Validation Checks: Like update, it will not save any changes if validations fail.
• Deprecated in Rails 6: Keep in mind that in Rails 6 and later versions, update_attributes is deprecated and aliased to the update method, steering developers towards the updated conventions.

Differences Between update and update_attributes

1. Deprecation: The primary difference as of Rails 6 is the deprecation of update_attributes. It's recommended to use update for future-proofing your applications.
2. Functionality: In earlier Rails versions, both methods performed the same task, but update_attributes was traditionally used for updating multiple fields.
3. Naming Convention: update carries a newer, more concise, and semantic naming aligned with Rails’ evolution.

Best Practices

• Use update: With the deprecation of update_attributes, update should be your go-to method for consistency and future compatibility.
• Ensure Validations: Always respect validations. Both methods interact with Rails’ validation system, ensuring that database integrity is maintained.
• Atomic Saves: Use these methods for efficient and atomic database updates without explicit save calls.

For deeper insights into Rails methods and their transition through versions, this article on Rails upgrades provides a comprehensive guide.

Conclusion

Both update and update_attributes play significant roles in updating records within Rails applications. While their functionality overlaps, the shift toward using update in modern Rails development is clear, especially for maintaining code maintainability and embracing updated conventions.

Understanding these tools not only enhances your coding practice but also aligns your applications with the best practices in the Rails community. Whether handling large user records or simple form updates, knowing when and how to use these methods will always be in your favor.