Re: Tomahawk 20-1.1.14: NestedNullException / BaseSortableModel.sort() contract violation / commandSortHeader and missing custom Comparator

Wed, 02 Aug 2017 09:00:58 -0700 

Thanks for your reply and your insights, Mike.
I'm unsure whether I'd come up with a better fix than you've suggested back then. Also, I'm afraid it's not possible for me to jump in as a new developer for tomahawk. 


Speaking of Primefaces as an alternative, I've been thinking about this, 
too, but there seems to be no such convenient way of applying auto-sort, 
as in Tomahawk, and it's somewhat unclear, if introducing a new 
primefaces dependency will harmonize with the existing code.


Best regards,
Sawin

On 2017-07-28 13:57, Mike Kienenberger wrote:

Note that while we have no current plans to release a new version of
tomahawk, we would be supportive of any volunteer jumping in, taking
over maintenance and new development of tomahawk, and rolling a
release.


On Fri, Jul 28, 2017 at 7:43 AM, Mike Kienenberger <mkien...@gmail.com> 
wrote:

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-awi...@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






















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