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Rails: Understanding save vs. save! Difference

by | Dec 2, 2023 | Active Record | 0 comments

When working with Ruby on Rails, you may find yourself needing to save a model instance to the database. Two methods used to accomplish this task are save and save!. While both methods save a record to the database, they behave differently when an error occurs during the save operation.

In this blog post, we’ll dive deeper into the differences between save and save!, and provide some guidance on when to use each method in your Rails applications.

The save Method

The save method is used to save a model instance to the database. When you call save, Rails attempts to save the record to the database. If the save operation fails, Rails returns false, and the record is not saved to the database. If the record has validation errors, save will return false and the errors will be added to the errors collection on the model instance.

Here’s an example of how to use the save method in Rails: 

# Create a new User instance
user = User.new(name: "John Smith", email: "john@example.com")

# Attempt to save the user to the database
if user.save
  # User was saved successfully
  puts "User saved!"
else
  # There was an error saving the user
  puts "Error saving user: #{user.errors.full_messages}"
end

In this example, we create a new User instance and attempt to save it to the database using the save method. If the save operation is successful, we output a success message. If there is an error saving the user, we output an error message along with any validation errors.

The save! Method

The save! method is similar to save in that it saves a record to the database. However, if the save operation fails for any reason, save! raises an exception instead of returning false. This means that any code that comes after the save! call will not be executed. save! is also more strict about validation errors – if any validation errors are present, save! will raise a RecordInvalid exception.

Here’s an example of how to use the save! method in Rails:

# Create a new User instance
user = User.new(name: "John Smith", email: "john@example.com")

# Attempt to save the user to the database
begin
  user.save!
  # User was saved successfully
  puts "User saved!"
rescue ActiveRecord::RecordInvalid => e
  # There was an error saving the user
  puts "Error saving user: #{e.message}"
end

In this example, we create a new User instance and attempt to save it to the database using the save! method. If the save operation is successful, we output a success message. If there is an error saving the user, we rescue the RecordInvalid exception that is raised and output an error message. Note that any code after the user.save! call will not be executed if an exception is raised.

When to Use Each Method

So when should you use each method? Use save when you want to save a record and check if it was saved successfully. This is useful when you need to handle validation errors or other save errors in your code.

Use save! when you want to save a record and you are sure that it should be saved successfully. This method is useful in situations where you want to ensure that a record is saved and any errors are caught and raised as exceptions. This can be helpful in preventing invalid or incomplete data from being saved to the database.

Another scenario where save! is useful is in database migrations, where you want to ensure that data is saved correctly during a migration. Because save! raises an exception if the save operation fails, it can be used to prevent invalid data from being saved during a migration.

In general, you should use save when you want to handle errors in your code and save! when you want to ensure that a save operation is successful and raise an exception if it fails.

Conclusion

In this blog post, we’ve explored the differences between save and save! in Ruby on Rails. While both methods save records to the database, they behave differently when an error occurs during the save operation. save returns false and adds validation errors to the errors collection, while save! raises an exception if the save operation fails.

By understanding the differences between save and save!, you can choose the appropriate method for your use case and ensure that your data is saved correctly in your Rails applications.

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