The <component> element maps properties of a child object to columns of the table of a parent class. Components may, in turn, declare their own properties, components or collections. See "Components" below.

<component 
        name="propertyName" 
        class="className"
        insert="true|false"
        update="true|false"
        access="field|property|ClassName"
        lazy="true|false"
        optimistic-lock="true|false"
        unique="true|false"
        node="element-name|."
>
        
        <property ...../>
        <many-to-one .... />
        ........
</component>

name: The name of the property.

class (optional - defaults to the property type determined by reflection): The name of the component (child) class.

insert: Do the mapped columns appear in SQL INSERT s?

update: Do the mapped columns appear in SQL UPDATE s?

access (optional - defaults to property): The strategy Hibernate should use for accessing the property value.

lazy (optional - defaults to false): Specifies that this component should be fetched lazily when the instance variable is first accessed (requires build-time bytecode instrumentation).

optimistic-lock (optional - defaults to true): Specifies that updates to this component do or do not require acquisition of the optimistic lock. In other words, determines if a version increment should occur when this property is dirty.

unique (optional - defaults to false): Specifies that a unique constraint exists upon all mapped columns of the component.

The child <property> tags map properties of the child class to table columns.

The <component> element allows a <parent> subelement that maps a property of the component class as a reference back to the containing entity.

The <dynamic-component> element allows a Map to be mapped as a component, where the property names refer to keys of the map, see Section 8.5, “Dynamic components”.