Active Record Validations Intro
Active Record validations are used to ensure that only valid data is saved to the database by validating the objects before they are saved. Active Record has a validation system allowing developers to specify rules for the attributes of a model. Common validations include presence, length, uniqueness, and custom validations.
They do not:
- validate previously saved data
- prevent all occurrences of invalid data being saved to a database.
Some common validations:
Presence
validates :some_important_attribute, presence: true
validates :several, :important, :attributes, presence: true
Uniqueness
validates :screenname, uniqueness: true