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>
public interface TransientAttributeDefinition<T> extends AttributeDefinition<T>
An attribute that does not map to an underlying database column.

Transient attributes are 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 derived values: 

public class Store extends DefaultDomain {

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

        // Database columns
        Column<Integer> ID = TYPE.integerColumn("id");
        Column<String> FIRST_NAME = TYPE.stringColumn("first_name");
        Column<String> LAST_NAME = TYPE.stringColumn("last_name");
        Column<String> EMAIL = TYPE.stringColumn("email");

        // Transient attributes
        Attribute<String> FULL_NAME = TYPE.stringAttribute("full_name");
        Attribute<Boolean> SELECTED = TYPE.booleanAttribute("selected");
        Attribute<String> TEMP_NOTES = TYPE.stringAttribute("temp_notes");
        Attribute<Object> UI_STATE = TYPE.attribute("ui_state", Object.class);
    }

    void defineCustomer() {
        Customer.TYPE.define(
                // Database columns
                Customer.ID.define()
                    .primaryKey(),
                Customer.FIRST_NAME.define()
                    .column(),
                Customer.LAST_NAME.define()
                    .column(),
                Customer.EMAIL.define()
                    .column(),

                // Derived transient attribute (computed from other attributes)
                Customer.FULL_NAME.define()
                    .attribute()
                    .derived(Customer.FIRST_NAME, Customer.LAST_NAME)
                    .valueProvider(sourceValues -> {
                        String first = sourceValues.get(Customer.FIRST_NAME);
                        String last = sourceValues.get(Customer.LAST_NAME);
                        return ((first != null ? first : "") + " " +
                                (last != null ? last : "")).trim();
                    })
                    .caption("Full Name"),

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

                // Temporary notes (modifies entity by default)
                Customer.TEMP_NOTES.define()
                    .attribute()
                    .caption("Temporary Notes"),

                // Generic UI state storage
                Customer.UI_STATE.define()
                    .attribute()
                    .modifies(false)
                    .caption("UI State"))
            .build();
    }
}

// Usage examples
Entity customer = entities.builder(Customer.TYPE)
    .with(Customer.FIRST_NAME, "John")
    .with(Customer.LAST_NAME, "Doe")
    .with(Customer.EMAIL, "john@example.com")
    .build();

// Transient attributes can be used for UI state
customer.set(Customer.SELECTED, true);  // Doesn't mark entity as modified
customer.set(Customer.TEMP_NOTES, "Important customer"); // Marks entity as modified

// Derived transient values are computed automatically
String fullName = customer.get(Customer.FULL_NAME); // "John Doe"

// UI state storage
customer.set(Customer.UI_STATE, new HashMap<String, Object>());

// Transient attributes are ignored during database operations
connection.insert(customer); // Only persists database columns

// Check modification state
boolean isModified = customer.modified(); // Only true if database columns changed
See Also:

  • Method Details

    • modifies

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