# Collection-handler Handler This handler is applicable when the persistence of this object is managed by the parent dataNode. The allowed attributes are:
**Attribute**
**Usage**
collection EL expression that identifies the collection onto which the business object must be added or removed
if EL expression that must be evaluated to true prior to handler action
unless EL expression that must be evaluated to false prior to handler action
The following example shows how you could manage objects City as a collection of objects within the object Country, which in turn is saved on a disk arhivo: ``` ```