9.1 Introduction to Programmatic Business Rules

Complementing its built-in declarative validation features, entity objects have method validators and several events you can handle to implement encapsulated business logic using Java code. By the end of this chapter, you'll understand all the concepts illustrated in Figure 9-1, and more:

• Attribute-level method validators trigger validation code when an attribute value changes.

• Entity-level method validators trigger validation code when an entity row is validated.

• You can override the following key methods in a custom Java class for an entity:

  • create(), to assign default values when a row is created

  • initDefaults(), to assign defaults either when a row is created or when a new row is refreshed

  • isAttributeUpdateable(), to make attributes conditionally updatable

  • remove(), to conditionally disallow deleting

  • prepareForDML(), to assign attribute values before an entity row is saved

  • beforeCommit(), to enforce rules that must consider all entity rows of a given type

  • afterCommit(), to send notifications about a change to an entity object's state

Figure 9-1 Key Entity Objects Features and Events for Programmatic Business Logic