This document provides an overview of validations in Ruby on Rails. It explains that validations ensure only valid data is saved to the database and are typically run before SQL commands. It lists various validation helper methods like presence, length, uniqueness and discusses validation options. Code examples are available on GitHub and the document cautions about methods that skip validations similarly to how one would be wary of good reviews for Michael Bay films.

1. Validations 101
Or: How I transitioned from Miley Cyrus to Michael Bay Jokes

2. The preamble
• All the code is available on github https://
github.com/ridget/validators_app
• @tjridge
• tomridge2@gmail.com

3. Validations are the bees
knees.
• Ensures only valid data is saved to the database
• Typically run before SQL insert/update commands sent to
the database.
• create/save/update methods trigger validations, if called
with a bang invalid records will return an exception, rather
than the object.
• Some methods like update_column and update_attribute
skip validation. save(:validate => false) skips validations
as well. Be as wary of these as you would be of good
reviews for a Michael Bay film.

4. Valid? Invalid?
• valid? Triggers validations, returns true if no errors are
found.
• invalid? Does the inverse.
• Object is valid if no errors found
• User.new could be technically invalid, but not return
any errors until save or valid? etc is called.
• Access error messages using .errors.messages
method on object.

5. Validation Helpers
• acceptance
• associated
• confirmation
• exclusion
• format
• inclusion
• length
• numericality
• presence
• absence
• uniqueness

6. Validation options
• if
• unless
• on (:create, :update)
• lets look at some code