[Wonder-disc] Subclassing ERD2WEditableListPage

[Marc B. <ma...@ad...>]

Hi to the list - my first post to this auspicious group.

We've finally decided to commit 100% to WOnder, largely for the ERD2W 
stuff and the excellent improvements in the rule engine, logging, and 
debugging that it brings. The extra components and code are just a 
great bonus for us. Thankyou to all, particularly Max (it was cool to 
meet you at WWDC last month), for this WOnderful body of work. (I say 
again, D2W rocks)

So... refactoring our frameworks and apps to fit the ER 'way', I've run 
across a couple of small problems.

We have our own component framework, IPDirectToWeb that augments the 
ERDirectToWeb and DirectToWeb frameworks.
The java package is net.iparadigm.ipdirecttoweb. It implements 
KeyValueCodingProtectedAccessor to ensure cross-package access.

Making use of all of these is our application package, 
net.iparadigm.directtoweb.

I'm attempting to subclass the ERD2WEditableListPage as 
IPD2WTableEditPage, and finally subclass that to 
IPD2WTableEditPageTemplate following the ER replaceable look and feel 
model.
Finally, I copied ERD2WEditableListPageTemplate.wo over to my own 
project's IPD2WTableEditPageTemplate
I've done this successfully with ERD2WQueryPage and other classes, so I 
thought I was on the right track.

The component renders normally if I give it a zero item list - it makes 
no unusual KVC requests of course in that case, except to resolve 
d2wContext.displayNameForEntity, which it does quite happily. I 
inserted a ERDDebuggingHelp component in the empty list case to verify 
that it is indeed my component that is being rendered with the right 
pageConfiguration, entity and so on.

However, at runtime, I get back a 
com.webobjects.foundation.NSKeyValueCoding$UnknownKeyException.
Specifically, valueForKey(): lookup of unknown key: 'dummy'
'dummy' is the binding for a hidden text field in the .wo, but notably 
it's declared protected. As a result, 'dummy' is invisible to the 
cross-package subclass. Removing the HiddenField element makes life 
good again.

Q1: So does 'dummy' really need to be there? I figure not.


The second issue we have with this component is that it assumes it's 
modal - that it will never be rendered as a sub-component. As a result 
the whole ErrorDictionary thing is questionable. The page only 
constructs enough error dictionaries for the number of items initially 
passed to it in the displayGroup. Once _errorMessagesDictionaries is 
initialised, the dg is never checked again.

My app makes a lot of use of Query/List components on the same page. 
currentErrorDictionary breaks immediately if you have, say, 5 items 
initially in the dg, then a subsequent query yields 6 EOs. 
currentErrorDictionary is going to gak with a subscript out of bounds 
exception the moment you try to render the component.

Somehow I need to workout when the dg has changed and execute 
clearValidationFailed at that time in order to kill the old 
dictionaries and make way for new ones to be created. I really don't 
want to have to keep a dg copy around for the comparison. Another way 
might be to somehow pass in a message from the containing component - 
but I don't know how to do that yet since I just switched to WOnder and 
I know you can't do that using the standard WOSwitchComponent.

Q2: Any suggestions as to the right way to do this please? I'll post 
the code once I fix it.


Thanks,
Marc

Currently Canadian, always Australian