Interface BeforeExecutionGenerator

All Superinterfaces:

Generator, Serializable

All Known Subinterfaces:

IdentifierGenerator, OptimizableGenerator, PersistentIdentifierGenerator

All Known Implementing Classes:

AbstractUUIDGenerator, CompositeNestedGeneratedValueGenerator, ForeignGenerator, GUIDGenerator, IncrementGenerator, NativeGenerator, OrderedSequenceGenerator, SequenceStyleGenerator, TableGenerator, UuidGenerator, UUIDGenerator, UUIDHexGenerator

public interface BeforeExecutionGenerator
extends Generator

A generator that is called to produce a value just before a row is written to the database. The generate(SharedSessionContractImplementor, Object, Object, EventType) method may execute arbitrary Java code. It may even, in principle, access the database via JDBC. But however it's produced, the generated value is sent to the database via a parameter of a JDBC prepared statement, just like any other field or property value.

Any BeforeExecutionGenerator with generation event types EventTypeSets.INSERT_ONLY may be used to produce identifiers. The built-in identifier generators all implement the older extension point IdentifierGenerator, which is a subtype of this interface, but that is no longer a requirement for custom id generators.

A custom id generator may be integrated with the program using either:

• the meta-annotation IdGeneratorType or
• the annotation GenericGenerator.

On the other hand, generators for regular fields and properties may be integrated using ValueGenerationType, as for any Generator.

Since:

6.2

Method Summary

Modifier and Type	Method	Description
Object	generate(SharedSessionContractImplementor session, Object owner, Object currentValue, EventType eventType)	Generate a value.
default boolean	generatedOnExecution()	Determines if the property value is generated when a row is written to the database, or in Java code that executes before the row is written.

Methods inherited from interface Generator

allowAssignedIdentifiers, allowMutation, generatedBeforeExecution, generatedOnExecution, generatesOnForceIncrement, generatesOnInsert, generatesOnUpdate, generatesSometimes, getEventTypes

Method Details

generate

Object generate(SharedSessionContractImplementor session,
 Object owner,
 Object currentValue,
 EventType eventType)

Generate a value.

Parameters:

session - The session from which the request originates.

owner - The instance of the object owning the attribute for which we are generating a value.

currentValue - The current value assigned to the property, or null

eventType - The type of event that has triggered generation of a new value

Returns:

The generated value

generatedOnExecution

default boolean generatedOnExecution()

Description copied from interface: Generator

Determines if the property value is generated when a row is written to the database, or in Java code that executes before the row is written.

• Generators which only implement BeforeExecutionGenerator must result false.
• Generators which only implement OnExecutionGenerator must result true.
• Generators which implement both subinterfaces may decide at runtime what value to return.

Specified by:

generatedOnExecution in interface Generator

Returns:

true if the value is generated by the database as a side effect of the execution of an insert or update statement, or false if it is generated in Java code before the statement is executed via JDBC.