> What I found was that I was instantiating my LDM's as private variables in
> my custom components but that they were not being detached. In this case
> you need to programatically register your non default models to participate
> in the detachment process. See the Wiki here for an example:
> http://cwiki.apache.org/confluence/display/WICKET/Working+with+Wicket+models#WorkingwithWicketmodels-ManagingthelifecycleofnondefaultdetachableIModel%27s
Which part there in particular? I read it and it didn't yet ring my bell...
is there really "another way" to register for onDetach events apart
from the model being directly involved in render cycle as a
formcomponent's or another component's defaultmodel?
> For your option 3 I would say you should create a custom IModel
> implementation that is aware of your caching strategy so that your
> Component's don't need to care about how the data is loaded.
Well.. that's the dream ;) Furthermore, I would like it to be more or
less automatic. Maybe models like:
1. SettingThisModelWillResetCacheModel extends IModel
2. SettingThisModelWillNOTResetCacheModel extends IModel
Furthremore, they would probably be created using a factory method in
a cache manager:
CacheManager cacheManager = new CacheManager(detachableToo);
cacheManager.newIndependentCachedModel(IModel ...)
cacheManager.newCachedModelWhoseChangeFiresExpire(IModel ...)
AND maybe I could chain cacheManagers to say "cache manger A will
expire if any of its dependent managers B-C-D expire."
Also it should be easy to add
cacheManager.addCacheExpirationListener(Runnable ..) or something.
...
Anybody else need something like this? We could write a draft and see
if it works and continue improving the design.
**
Martin
>
> Your implementation could hold a Map of all related models and update
> according to your rules or better yet build a service that does the caching
> and dirty detection and then just have the LDM source the cell value from
> the service. Something like:
>
> new LoabableDetachableModel () {
>
> protected CellValue load () {
>
> return cellService.getValue (row, col);
> }
> }
>
> Regards,
>
> Mike
>
>>> evaluated only one time per render can be done with
>>> LoadableDetachedModel ..
>>>
>>
>> I do not mean LOADED once per render. I mean EVALUATED once per
>> render. In my understanding LoadableDetachableModel does not guarantee
>> "reset" in any particular stage.
>>
>>
>>>
>>> can you explain it a littly bit (a link to your original message?)
>>>
>>
>> I mean for rexample I have many models like this:
>>
>> new AbstractReadOnlyModel<String>() {
>> public String getObject() {
>> // evaluate message with some logic
>> return message;
>> }
>> }
>>
>> Furthermore, I have several components that, say, depend on this
>> value. This getObject() will be called many times durung render and
>> the logic will be evaluated many times.
>>
>> If I make it detachable it will yes be detached but I am not sure that
>> the detaching is guaranteed at some specific point in request cycle?
>>
>> To make my "use case" more clear I will give an example: say I have a
>> wicket page with a panel that contains a table with columns rows and y
>> rows. Furthermore, let's assume it is a spreadsheet emulator: you can
>> write formulas into the cells that depend on the other cells which
>> means that the value of each cell is recursively evaluated dependent
>> on the other cell's values.
>>
>> Requirements:
>> 1. During render time each cell's model value should be cached once it
>> has been evaluated (we do not want to recurse many times to fetch the
>> same value).
>> 2. If the value of any cell changes, all the dependent cells should be
>> (for example) ajax refreshed and re-evaluated. For simplicity, we
>> could re-set the cache of all models when change occurs. And
>> redraw-all.
>> 3. We want to reset cache ONLY if change occurs.
>>
>> In my understanding requirement 3 cannot be directly reached with
>> detachable models.
>>
>> **
>> Martin
>>
>>
>
>
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org
For additional commands, e-mail: users-h...@wicket.apache.org
