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From: Mike Kienenberger <mkienenb@gmail.com>
Date: Fri, 28 Jul 2017 07:43:21 -0400
Message-ID: <CAM1yOjbF+ySPdxwazpzuhO2mmbOytm=7tpDfiicJDrw4GmnY7A@mail.gmail.com>
Subject: Re: Tomahawk 20-1.1.14: NestedNullException / BaseSortableModel.sort()
 contract violation / commandSortHeader and missing custom Comparator
To: MyFaces Discussion <users@myfaces.apache.org>
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archived-at: Fri, 28 Jul 2017 11:43:52 -0000

We don't currently have any committers actively working on tomahawk.

The original JIRA for that was
https://issues.apache.org/jira/browse/TOMAHAWK-952 and it looks like I
only started to do the groundwork add that support.

As this was 10 years ago, I don't really remember any details about it.

My clients have long ago switched over to primefaces.  I have only one
legacy app in maintenance mode that uses tomahawk, so I doubt I will
ever revisit working on this.

Your best bet is to file a bug and propose a fix in the form of a
unified diff.  While someone (maybe me) will apply that fix, I don't
know if we have any plans to do an official tomahawk release any time
soon.

From my email, it looks like part of the problem was determining how
to maintain backwards compatibility short of subclassing the model.  I
guess you could try a delegating approach.  Sorry, but I doubt I will
be of any more help than that.


On Tue, Jul 25, 2017 at 8:01 AM, s-awinte <s-awinte@haw-landshut.de> wrote:
> Hi,
>
> I'm currently trying to use a <t:commandSortHeader> Tomahawk tag inside
> <t:column defaultSorted="true" sortable="true"> with auto sorting, similar
> to the example here:
> https://wiki.apache.org/myfaces/Working_with_auto_sortable_tables
>
> Problem is, the tag's "propertyName" references to a string property of an
> attribute of a given entity object (which itself does not extend
> BaseSortableModel) and the entity's attribute is optional (nullable), which
> will lead to a NestedNullException:
>
> ERROR [org.apache.myfaces.component.html.ext.SortableModel]...
> org.apache.commons.beanutils.NestedNullException: Null property value for
> 'attribute.shortName' on bean class 'class
> com.my.app.model.food.exotic.fruit'
> ...
> javax.faces.FacesException: java.lang.IllegalArgumentException: Comparison
> method violates its general contract!
> at
> javax.faces.component.UIComponentBase$AttributesMap.get(UIComponentBase.java:2352)
> ...
> Caused by: java.lang.IllegalArgumentException: Comparison method violates
> its general contract!
>     at java.util.TimSort.mergeLo(TimSort.java:777) [rt.jar:1.8.0_60]
>     at java.util.TimSort.mergeAt(TimSort.java:514) [rt.jar:1.8.0_60]
>     at java.util.TimSort.mergeCollapse(TimSort.java:439) [rt.jar:1.8.0_60]
>     at java.util.TimSort.sort(TimSort.java:245) [rt.jar:1.8.0_60]
>     at java.util.Arrays.sort(Arrays.java:1512) [rt.jar:1.8.0_60]
>     at java.util.ArrayList.sort(ArrayList.java:1454) [rt.jar:1.8.0_60]
>     at java.util.Collections.sort(Collections.java:175) [rt.jar:1.8.0_60]
>     at
> org.apache.myfaces.component.html.ext.BaseSortableModel.sort(BaseSortableModel.java:201)
> [tomahawk20-1.1.14.jar:1.1.14]
>     at
> org.apache.myfaces.component.html.ext.BaseSortableModel.setComparator(BaseSortableModel.java:62)
> [tomahawk20-1.1.14.jar:1.1.14]
>     at
> org.apache.myfaces.component.html.ext.SortableModel.setSortCriteria(SortableModel.java:143)
> [tomahawk20-1.1.14.jar:1.1.14]
>     at
> org.apache.myfaces.component.html.ext.AbstractHtmlDataTable.createDataModel(AbstractHtmlDataTable.java:1643)
> [tomahawk20-1.1.14.jar:1.1.14]
>     at
> org.apache.myfaces.component.html.ext.HtmlDataTableHack.getDataModel(HtmlDataTableHack.java:932)
> [tomahawk20-1.1.14.jar:1.1.14]
>     at
> org.apache.myfaces.component.html.ext.AbstractHtmlDataTable.getDataModel(AbstractHtmlDataTable.java:1597)
> [tomahawk20-1.1.14.jar:1.1.14]
>     at
> org.apache.myfaces.component.html.ext.HtmlDataTableHack.getRowCount(HtmlDataTableHack.java:103)
> [tomahawk20-1.1.14.jar:1.1.14]
>     at sun.reflect.GeneratedMethodAccessor32969.invoke(Unknown Source)
> [:1.8.0_60]
>     at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> [rt.jar:1.8.0_60]
>     at java.lang.reflect.Method.invoke(Method.java:497) [rt.jar:1.8.0_60]
>     ...
>
>
> As I understand it, the row Objects of a sortable <t:dataTable> column are
> being automatically wrapped in SortableModel, which brings its own
> "RowDataComparator" via BaseSortableModel.sort(), which seems to be
>
> a) not null-safe (for the wrapped model)
> b) not supporting nulls first/last
> c) in this case violating the Comparator contract
>
> Regardless of the contract violation problem (probably due to a
> NestedNullException inside RowDataComparator or because
> BaseSortableModel.sort() never returning -1), I'd like in general to be able
> to use a custom Comparator here, which can handle nested nulls and
> implements a customized comparison, but <t:commandSortHeader> does not seem
> to support this.
>
> Most references I find, completely ignore the commandSortHeader auto-sorting
> and do the implement a custom backing Bean.sort(), an approach I'd like to
> avoid, if possible.
>
> There would seem to exist a solution for the problem in this somewhat dated
> example here, but it's unclear to me, if it ever managed to make it into
> tomahawk's code base:
> http://grokbase.com/t/myfaces/dev/073ev810b8/sortablemodel-and-t-datatable-changes-improvements
>
> In Trinidad, it would seem, that there was a similar (now resolved) issue:
> https://issues.apache.org/jira/browse/TRINIDAD-1965
>
> I could not figure out how this applies to Tomahawk, though, or if the
> example above has been implemented by now, and I could not find any working
> code example that would support this assumption.
>
> Also, I do not see how SortableModel.setSortCriteria() ->
> BaseSortableModel.setComparator() could be utilized in this scenario without
> letting the entity model extend BaseSortableModel or SortableModel, which
> seems not feasable, due to my model already extending several other classes.
> Is using a custom Comparator not supported in Tomahawk still, or, if so,
> where can I find code examples or documentation describing how to use this
> feature?
>
> If not, are you planning on fixing this issue anytime soon and should I file
> a bug about the NestedNullException / contract violation problem, too?
>
>
> Best regards,
> Sawin