Intro to validations in rails, code at https://github.com/ridget/validators_app

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