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https://issues.apache.org/jira/browse/WICKET-1784?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12626796#action_12626796
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R. Goodwin commented on WICKET-1784:
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Hello Igor,
Well, everything's possible to implement externally isn't it.
But was I saying it was so easy ... for the long term?
Subclassing RefreshingView means losing (or re-writing) the functionality in
AbstractPageableView,
including all that stuff with versioning and the Change object.
Bit too much detail for someone just starting out with Wicket isn't it?
And are you confident that data retrieval by DTO is a rare use case?
It's easy to write off J2EE patterns as out of date. But the Transfer Object
pattern resurfaces in mysterious ways. For example, how could one integrate
Wicket with the 3-tier Command pattern for data access suggested by Bauer and
King in Java Persistence with Hibernate? pp. 718-724. Their solution also
behaves like a DTO-over-the-wire pattern too.
You know, the really great frameworks like Hibernate and Spring always provide
helper classes for those tricky situations. Having to extend a framework class
midway through the class hierarchy is really a last resort.
:)
Have you seen:
http://www.nabble.com/Paging-query-relating-to-IDataProvider-and-Lucene-search-td19083164.html
> Enhance IDataProvider to support applications using the Transfer Object J2EE
> pattern
> ------------------------------------------------------------------------------------
>
> Key: WICKET-1784
> URL: https://issues.apache.org/jira/browse/WICKET-1784
> Project: Wicket
> Issue Type: Improvement
> Components: wicket
> Affects Versions: 1.3.3, 1.4-M3
> Environment: Wicket 1.3.3 and 1.4-M3
> Reporter: R. Goodwin
> Assignee: Igor Vaynberg
> Attachments: wicket-paging-experiment.zip
>
>
> In some environments searches are performed in 'single call' fashion, using a
> transfer object.
> E.g. two queries performed by the data services tier before returning
> combined results to the UI tier:
> i. Query for paged search results
> ii. Query for a 'count' value representing total possible results
> The contract between DataView and IDataProvider does not support a 'single
> call' environment as the give/take relationship between these classes is
> biased towards DataView.
> DataView expects IDataProvider to provide it's size before providing
> IDataProvider with its offset and count.
> * DataView may have good reasons for needing size before it can provide
> offset/count.
> * But IDataProvider has equally good reasons for needing offset/count before
> it can provide size.
> The circular dependency:
> 1. DataView calls IDataProvider.size()
> 2. IDataProvider cannot return size as it cannot start a query until it
> receives offset/count from DataView
> 3. These it does not receive until DataView calls IDataProvider.iterator()
> later on
> Others who experienced this problem (with CODE examples):
> * http://www.nabble.com/IDataProvider-and-Hibernate-Search-td15546101.html
> * http://www.mail-archive.com/[EMAIL PROTECTED]/msg14266.html
> ---
> The suggested solution of caching the combined search results and count value
> does not work if the search cannot begin until offset and count are
> available. And writing a custom DataView is not feasible either time wise as
> I understand that it cannot be done without needing to write a number of
> other classes too.
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