[Seaside] Component lifecycle and how to use announcement on a model

Tim Mackinnon tamackinnon at gmail.com
Wed Aug 11 22:23:42 UTC 2010

Hi guys - as I drill through my "once simple" toy application (actually 
its not that bad - particularly compared to the java/gwt stuff I get at 
work) - I keep coming up with features that excercise new parts of 

I currently have a "model" that I store as a class variable on my root 
component. As i've split out bits of functionality from my app and 
moved them into sub-components, I've instantiated those components with 
that same shared model so they could render different parts of it. I 
think this is the right style...?

Anyway in adding a new "Remove button" feature, it felt like it should 
live in an existing items list component - however a model update can 
require an ajax update to redraw my model state so everything looks 
right (and its my main component that coordinates this).

So it seemed like a perfect fit for Announecments - my root could 
subscribe to a model change and then coordinate the ajax update of the 
correct components.

I did this , and then started getting updates all over the place (even 
unexpectedly) - I'm thinking that when I subscribe to my Announcements, 
I shouldn't do this in the #initialize of my root component? I think I 
must get a new initialize every time I refresh the page - and so 
register another notification?

So I'm wondering what the lifecycle of a WAComponent is? And where/how 
I should initialize a singleton model? I've read the bits about 
session's - but in my case I want multiple browsers to share the same 
model (so each would be in its own session - so I don't think I want to 
go that route?).

Do I lazy initialize the subscription along with the singleton model 
(or is there a better way)? And when do I unsubscribe? I think I'm 
missing the info about the component lifecycle - where should I look to 
understand/read about that?


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