Module is.codion.framework.domain
Package is.codion.framework.domain.entity.attribute

Interface TransientAttributeDefinition<T>

Type Parameters:
T - the attribute value type
All Superinterfaces:
AttributeDefinition<T>, ValueAttributeDefinition<T>
public sealed interface TransientAttributeDefinition<T> extends ValueAttributeDefinition<T>
An attribute that does not map to an underlying database column.

TransientAttributeDefinition extends ValueAttributeDefinition for attributes used for temporary data, UI state, calculated values, or any other data that should not be persisted to the database. They are initialized to null when entities are loaded and ignored during DML operations.

The value of transient attributes can be set and retrieved like normal attributes but are ignored during insert, update, and delete operations. By default, setting a transient value marks the entity as modified, but trying to update an entity with only transient values modified will result in an error.

Transient attributes are useful for UI state, temporary calculations and values the record carries without storing. They are editable fields wherever the framework builds components from attribute definitions, which is what makes them the way a form holds something the table does not store: 

interface Customer {
	EntityType TYPE = DOMAIN.entityType("chinook.customer");

	// Database columns
	Column<Long> ID = TYPE.longColumn("id");
	Column<String> FIRSTNAME = TYPE.stringColumn("firstname");
	Column<String> LASTNAME = TYPE.stringColumn("lastname");

	// Transient attributes
	Attribute<Boolean> SELECTED = TYPE.booleanAttribute("selected");
	Attribute<String> NOTES = TYPE.stringAttribute("notes");
}

EntityDefinition customer() {
	return Customer.TYPE.as()
					.attributes(
									// Database columns
									Customer.ID.as()
													.primaryKey(),
									Customer.FIRSTNAME.as()
													.column()
													.caption("First name"),
									Customer.LASTNAME.as()
													.column()
													.caption("Last name"),

									// UI state attribute that doesn't modify entity
									Customer.SELECTED.as()
													.attribute()
													.modifies(false) // Doesn't mark entity as modified
													.defaultValue(false)
													.caption("Selected"),

									// Temporary notes (modifies entity by default)
									Customer.NOTES.as()
													.attribute()
													.caption("Notes"))
					.build();
}

void customers(EntityConnection connection) {
	// Transient attributes are initialized to null when entities are loaded
	Entity customer = connection.selectSingle(Customer.ID.equalTo(1L));

	customer.set(Customer.SELECTED, true);
	customer.modified(); // false, SELECTED doesn't modify the entity

	customer.set(Customer.NOTES, "Important customer");
	customer.modified(); // true, NOTES modifies the entity

	// Transient attributes are ignored during database operations,
	// updating an entity with only transient values modified results in an error
}
See Also:

  • Method Details

    • modifies

      boolean modifies()
      Returns:
      true if the value of this attribute being modified should result in a modified entity