= Schema Validations

Schema Validations is a plugin that reads various constraints defined against columns in your database and applies the closest matching rails validation. (Ala Dave Thomas' Keynote.)

Over and above installing the plugin, no further action is required for the validations to take effect; the database schema constraints will be read and applied as validations when your ActiveRecord model classes are loaded; just like magic.

The plugin supports the following constraints:

• NOT NULL is converted to +validates_presence_of+ (including +belongs_to+ associations);
• Numbers are checked using +validates_numericality_of+ (including :only_integer => true);
• String lengths are checked using +validates_length_of+;
• Single-column unique indexes are converted to +validates_uniqueness_of+; and
• Multi-column unique indexes are converted to +validates_uniqueness_of+ with +scope+.

For multi-column unique indexes the column validated for uniqueness is either the last column not ending in '_id' or simply the last column. This follows the typical composite unique index column ordering where the scoping is specified first but will attempt to find the last non-foreign-key column just-in-case.

For example, either of the following two statements in a schema migration script:

add_index :states, [:country_id, :name], :unique => true add_index :states, [:name, :country_id], :unique => true

would result in:

validates_uniqueness_of :name, :scope => [:country_id]

Validation may be limited to specific columns by calling schema_validations from within your model class, passing either a single column:

class Country < ActiveRecord::Base schema_validations :only => :name end

or an array of columns:

class Country < ActiveRecord::Base schema_validations :except => [:isocode, :iddcode] end

=== Dependencies

• RedHill on Rails Core (redhillonrails_core).

=== License

This plugin is copyright 2006 by RedHill Consulting, Pty. Ltd. and is released under the MIT license.