What are some examples of Active Record validations in Rails?

What are some examples of Active Record validations in Rails?

Active Record validations ensure that only valid data is saved to the database. Here are a few examples:

1. validates :name, presence: true - Ensures the name is present.
2. validates :email, uniqueness: true - Ensures the email is unique.
3. validates :age, numericality: { only_integer: true } - Ensures age is an integer.

Can you explain the presence validation in more detail?

Sure! The presence validation checks that a specified attribute is not empty. If the attribute is blank, the record will not be saved, and an error message will be added. For example:

validates :username, presence: true
``` This ensures that the username must be provided.

What happens if a validation fails?

If a validation fails, the record will not be saved to the database, and the errors will be added to the model's errors collection. You can then display these errors to the user.

Can I customize the error messages?

Yes, you can customize error messages by passing a message option. For example:

validates :email, presence: { message: 'Email cannot be blank' }
``` This will display your custom message when the validation fails.