12 Validation

Grails validation capability is built on Spring’s Validator API and data binding capabilities. However Grails takes this further and provides a unified way to define validation "constraints" with its constraints mechanism.

Constraints in Grails are a way to declaratively specify validation rules. Most commonly they are applied to domain classes, however URL Mappings and Command Objects also support constraints.

• 12.1 Declaring Constraints
• 12.2 Validating Constraints
• 12.3 Sharing Constraints Between Classes
• 12.4 Validation on the Client
• 12.5 Validation and Internationalization
• 12.6 Applying Validation to Other Classes