[#GROOVY-2786] ObservableMap doesn't fire Property Change Event upon removal

groovy

ObservableMap doesn't fire Property Change Event upon removal

Created: 27/Apr/08 04:30 PM Updated: Wednesday 01:40 PM

Component/s:

None

Affects Version/s:

1.5.6

Fix Version/s:

1.6-beta-2

Time Tracking:

Not Specified

Description

« Hide

Taking the example from doc

def map = [one: 1, two: 2] as ObservableMap
map.addPropertyChangeListener({evt -> println "${evt.propertyName}: ${evt.oldValue} -> ${evt.newValue}"} as PropertyChangeListener)

map.remove("one")

nothing is printed. Other operations like put, replace element do work without problem.

map.clear() also do nth. as putAll() does fire events, i think clear() should do so.

All

Comments

Work Log

Change History

Sort Order:

Ascending order - Click to sort in descending order

[ Permlink | « Hide ]

Alex Peters - 28/Apr/08 09:42 AM

I took a look at the remove and clear method. they do not fire any property change event.
but is this really a bug or should more documentation explain the behaviour?

PropertyChangeEvent requires an oldValue and newValue.
When i remove a key from the map what values should the event carry?

[ Permlink | « Hide ]

Guillaume Laforge - 28/Apr/08 09:52 AM

I think it's designed that way.
But Andres may shade some more light on this?

[ Permlink | « Hide ]

Andres Almiray - 28/Apr/08 12:45 PM

As Guillaume noted, it is designed that way, the intention of ObservableMap is to mimic an observable bean, you can't remove properties from a bean, can you?

On the other hand I see the benefit of having OM publish events when an element or all elements are removed, but the event triggered should not be a PropertyChangeEvent. This may be confusing as OM currently sends a PCE when a 'new" property is "added", so it should trigger a PropertyAddedEvent instead, but in a sense OM holds every property possible from the start (again if trying to mimic an observable bean).

Two questions remain then:
a) should PropertyRemovedEvent/PropertiesClearedEvent be added to OM ?
b) if a) should PropertyAddedEvent be triggered when a "new" property is added to the map ?

[ Permlink | « Hide ]

Mingfai Ma - 28/Apr/08 06:17 PM

I guess we agree it's necessary to fire removal event. Otherwise, the Observable Map is somehow useless.

>PropertyChangeEvent requires an oldValue and newValue.
>When i remove a key from the map what values should the event carry?

If an entry is removed, I expect it to return:
assert( evt.newValue == null )

[ Permlink | « Hide ]

Andres Almiray - 28/Apr/08 06:45 PM

Alright, then I think the best course of action would be to subclass PCE to add a type [add|remove|change|clear] and continue using PropertyChangeListener. If a client would like to know more about the event then it can read the type field.

[ Permlink | « Hide ]

Andres Almiray - 14/May/08 01:24 PM

Added the following detail to fired events

ObservableMap.PropertyAddedEvent - a new property is added to the map
ObservableMap.PropertyRemovedEvent - a property is removed from the map
ObservableMap.PropertyUpdatedEvent - a property changes value (same as regular PropertyChangeEvent)
ObservableMap.PropertyClearedEvent - all properties have been removed from the map
ObservableMap.MultiPropertyAddedEvent - triggered by calling map.putAll(), contains Added|Updated events

[ Permlink | « Hide ]

Andres Almiray - 14/May/08 01:40 PM

Backported to 1.5.x