Hello, How can I get the children of a WOComponent? More importantly, all children and all descendants?
WOComponents seem to only know how to go up the tree (find their parents). If you ask a WOComponent for its template (which is roughly its .html/.wod structure), you can then *almost* ask the template to go down the tree for its children as WOComponents. This is not straightforward because as far as I can tell, you got to do a lot of "cursor incrementing" and tricky instantiation of WOComponents. Not only do you have to deal with the "template" but you must also consider a "_childTemplate" for when you've got WOComponentContent and WOComponentReference objects. I've got some code now that doesn't quite work because on a complex page it gets the bindings confused when I try to push a WOComponentReference into context. I've asked a similar question about a day ago on the WOnder list, but I've learned a bit more and realize it may be more appropriate to ask the question here. So sorry if this appears to be a bit of deja vu for those who read both lists but it's actually a bit more than that. If you read the earlier message, please disregard it as I believe this one is more meaningful. Consider the following code snippet offered by Mr. Rentzsch: http://www.wodeveloper.com/omniLists/webobjects-dev/2002/July/msg00246.html I got so excited when I saw this only to find out that this example only works in the trivial case, when you don't have any WOComponentContent such as a PageWrapper component. To make it work in the general case appears to be very tricky and also inefficient. The reason why I'm doing this is because I'm trying to bootstrap a phase into the request-response loop. In any given reuseable subcomponent I'm designing, I want to be able to simply implement "addRequiredWebResources(WOResponse, WOContext)". Inside this method I would make calls that would examine the HTML response content and insert multiple lines between the HTML head tags. For example, CSS file resources and Javascript file resources. This way I don't need monolithic CSS and JS files but can break the files down and associate them with the reusable components that need them. When a page is rendered to the user, only the necessary JS and CSS resources are referred to in the link and import statements of the head tag, automatically. For this to work fully, appendToResponse() must go first so that we have some "head" tags to discover. But before appendToResponse() is done, it needs to call "addRequiredWebResources()" on every possible subComponent in the tree... *every* one of them. This means it needs to contact even those subComponents that are inside of WOConditional containers that evaluated to false. So yes, there would be many components whose "appendToResponse()" was not called but "addRequiredWebResources()" was in fact called. Before the world of partial page refreshes via AJAX and other means, none of this mattered. But now, because I can refresh a portion of the screen and show a previously missing "coolWidget" subComponent that requires "coolLib.js" I'm in trouble. Problem is, in a partial page refresh, there is no "head" tag so "coolWidget" will fail horribly because "coolLib.js" is not referenced between the head tags of the page. In a full page refresh (before the Web 2.0 era) there is no problem because the head tag is readily available. Get the picture? I really need some advice here or a sample of how to get to all the children and children's children of the outmost WOComponent. Conceptually it would also be interesting to understand why Apple only exposes the "parent" relationship of a WOComponent. When you *really* think about it, it makes a lot of sense to get to your children and not so much to get to the parent. Obviously internally WebObjects knows how to get to the children, otherwise appendToResponse won't work. You kind of need to know how to get to the guys underneath you. Every time I think about the "parent" relationship the usefulness of it smacks of *clever*. Like maybe executing the action of a parent WOComponent. But once you do something like that, you've heavily tied the subComponent to the parent and it no longer becomes reuseable. Think of a car tire. That tire should work no matter what car I put it on. I should be able to pull it from one truck and place it on another without a care in the world. If the tire wants to let us know that its air pressure is low then it would just shout "airPressureLow()" and the right components of the car should be registered to listen to that message, so there is no need to get to the "parent()". I fear, without an adequate answer to the question of "how do I get to my children", our beloved tool of choice can no longer provide truely reusable WOComponents for the Web 2.0 era. -- Aaron
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