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https://issues.apache.org/jira/browse/WICKET-663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13852122#comment-13852122
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Igor Vaynberg commented on WICKET-663:
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the way this works currently is:
lets say i pick a choice rendered as "17". when we need to resolve this back
from the client string to the object we load up all the choices, go through
them one by one, render the id using the renderer, and look for the match.
this is ok for most cases, but when you have multiple filters on the page each
with 200ish choices this may get slow because not only are you doing a linear
search across all options, you are also loading all options from the database
or other potentially slow storages.
the idea behind this ticket is to make that reverse lookup ("17"->object)
configurable. for large dropdowns a good optimization can be to simply cast
"17" to 17 and load the object with that id from the database.
there are two places for this kind of lookup: a method on the component and a
method in the renderer.
imho the better place is the renderer because that is the more likely place for
specializations to occur and since renderer is the thing that transcodes an
object into a string representation it makes it logical that it handles the
inverse. for example we have an EntityChoiceRenderer that knows how to pull the
database id out of entities; it makes it a logical place to override the
lookup. so we would have an EntityChoiceRenderer that knows how to deal with
entities in a more complete way: encode them into html and decode them
efficiently.
this would change the renderer from an interface into an abstract class, thus
wicket 7.0, so it can provide the default linear lookup. maybe {code}T
getObject(String value, IModel<List<T>> choices){code}. im not sure if the
component instance would be useful in the method signature, my feeling that
most likely not really and if its needed the user can pass it in manually.
> enhance ichoicerenderer with id->choice object lookup
> -----------------------------------------------------
>
> Key: WICKET-663
> URL: https://issues.apache.org/jira/browse/WICKET-663
> Project: Wicket
> Issue Type: Improvement
> Affects Versions: 1.3.0-final
> Reporter: Igor Vaynberg
> Assignee: Igor Vaynberg
>
> add object idtochoice(string id) to ichoicerenderer and add class
> choicerenderer implements ichoicerenderer that encapsulate the default linear
> search
> then we can remove method added in WICKET-348 to support a custom lookup
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