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Posted to dev@commons.apache.org by "Jacob Kjome (JIRA)" <ji...@apache.org> on 2007/01/22 21:34:29 UTC
[jira] Created: (BEANUTILS-268) BeanComparator.compare() doesn't
can't handle null values returned by bean properties
BeanComparator.compare() doesn't can't handle null values returned by bean properties
-------------------------------------------------------------------------------------
Key: BEANUTILS-268
URL: https://issues.apache.org/jira/browse/BEANUTILS-268
Project: Commons BeanUtils
Issue Type: Bug
Components: Bean-Collections
Affects Versions: 1.7.0
Reporter: Jacob Kjome
I've got a bean that has properties that will, at times, return null values. BeanComparator appears to fail with a NullPointerException. It's difficult to tell exactly where because the exception thrown is a ClassCastException with a message of e.toString(), so all I know is that a NullPointerException happened, not where it happened.
I suspect that the exception happens inside the compare(Object, Object) method with the call...
Object value1 = PropertyUtils.getProperty( o1, property );
Looking into PropertyUtils, and following the path, it seems like the problematic code is in...
PropertyUtilsBean.getNestedProperty(Object, String)
That code is rather involved. If I get around to performing a minimal testcase, I'll see if I can narrow down the exception to a particular piece of code. In any case, there's no reason why a bean shouldn't be allowed to return null for a given property.
My workaround is to add methods for respective properties that are guaranteed to not return null. For instance, if I have a getter called getMyValue(), I create a corresponding method called getMyValueNotNul(). I have to take care with the value it returns, though. The position in a sort for a null value would be different than a literal empty String. So, depending on the Object type, I have to make up values which will either come before all other non-null values or after all other non-null values (I don't recall what the natural order of null values are; whether they come first or last. I know when ordering on a SQLcolumn, null values show up last. Hopefully that behavior is consistent here, but that's beside the point here).
I hope this can be fixed before 1.8.0 is released!
Jake
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[jira] Commented: (BEANUTILS-268) BeanComparator.compare() doesn't
can't handle null values returned by bean properties
Posted by "Jacob Kjome (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/BEANUTILS-268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466661 ]
Jacob Kjome commented on BEANUTILS-268:
---------------------------------------
My point about the comparators was that the statement implies that BeanComparator's default internal comparator doesn't deal with null values and that one would need to be provided that does if the beans in question might return null for their properties. Maybe I misinterpreted, but there's no point in stating it the way it is stated if BeanComparator's default internal comparator does, in fact, deal with null values. Because in that case, it's not a necessity to provide a custom comparator to the constructor. Instead, it should read something like...
"Custom comparators should deal with the possibility of null values returned by bean properties or risk a NullPointerException"
The above is more to the point and implies that BeanComparator's default internal comparator deals with null bean property values, which really ought to be the case, especially in a library that is supposed to be non-brittle....
But then again, after looking at the code, ComparableComparator does *not* deal with null values. And that's the reason for the NullPointerException I'm getting. Of course the error message could have been better to point that out in the first place. I see it has been address in the latest version.
I guess the way to deal with null values is to use the commons-collections NullComparator. And I suppose when using the ReverseComparator, I'd need to provide it with the NullComparator in order for it to avoid NullPointerExceptions. Ok, I think I get it.
Closing as invalid.
Jake
> BeanComparator.compare() doesn't can't handle null values returned by bean properties
> -------------------------------------------------------------------------------------
>
> Key: BEANUTILS-268
> URL: https://issues.apache.org/jira/browse/BEANUTILS-268
> Project: Commons BeanUtils
> Issue Type: Bug
> Components: Bean-Collections
> Affects Versions: 1.7.0
> Reporter: Jacob Kjome
>
> I've got a bean that has properties that will, at times, return null values. BeanComparator appears to fail with a NullPointerException. It's difficult to tell exactly where because the exception thrown is a ClassCastException with a message of e.toString(), so all I know is that a NullPointerException happened, not where it happened.
> I suspect that the exception happens inside the compare(Object, Object) method with the call...
> Object value1 = PropertyUtils.getProperty( o1, property );
> Looking into PropertyUtils, and following the path, it seems like the problematic code is in...
> PropertyUtilsBean.getNestedProperty(Object, String)
> That code is rather involved. If I get around to performing a minimal testcase, I'll see if I can narrow down the exception to a particular piece of code. In any case, there's no reason why a bean shouldn't be allowed to return null for a given property.
> My workaround is to add methods for respective properties that are guaranteed to not return null. For instance, if I have a getter called getMyValue(), I create a corresponding method called getMyValueNotNul(). I have to take care with the value it returns, though. The position in a sort for a null value would be different than a literal empty String. So, depending on the Object type, I have to make up values which will either come before all other non-null values or after all other non-null values (I don't recall what the natural order of null values are; whether they come first or last. I know when ordering on a SQLcolumn, null values show up last. Hopefully that behavior is consistent here, but that's beside the point here).
> I hope this can be fixed before 1.8.0 is released!
> Jake
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[jira] Commented: (BEANUTILS-268) BeanComparator.compare() doesn't
can't handle null values returned by bean properties
Posted by "Niall Pemberton (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/BEANUTILS-268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466634 ]
Niall Pemberton commented on BEANUTILS-268:
-------------------------------------------
Hi Jake,
On your point about "shouldn't all comparators handle null values" - maybe/probably but since they're not part of BeanUtils then its not a relevant issue here.
If the issue is cause by PropertyUtilsBean I'm also not sure if theres a suitable solution that could be implemented in BeanComparator - but then perhaps you'll prove me wrong and produce one!
I'll leave this open for now until you've narrowed down the problem.
Niall
> BeanComparator.compare() doesn't can't handle null values returned by bean properties
> -------------------------------------------------------------------------------------
>
> Key: BEANUTILS-268
> URL: https://issues.apache.org/jira/browse/BEANUTILS-268
> Project: Commons BeanUtils
> Issue Type: Bug
> Components: Bean-Collections
> Affects Versions: 1.7.0
> Reporter: Jacob Kjome
>
> I've got a bean that has properties that will, at times, return null values. BeanComparator appears to fail with a NullPointerException. It's difficult to tell exactly where because the exception thrown is a ClassCastException with a message of e.toString(), so all I know is that a NullPointerException happened, not where it happened.
> I suspect that the exception happens inside the compare(Object, Object) method with the call...
> Object value1 = PropertyUtils.getProperty( o1, property );
> Looking into PropertyUtils, and following the path, it seems like the problematic code is in...
> PropertyUtilsBean.getNestedProperty(Object, String)
> That code is rather involved. If I get around to performing a minimal testcase, I'll see if I can narrow down the exception to a particular piece of code. In any case, there's no reason why a bean shouldn't be allowed to return null for a given property.
> My workaround is to add methods for respective properties that are guaranteed to not return null. For instance, if I have a getter called getMyValue(), I create a corresponding method called getMyValueNotNul(). I have to take care with the value it returns, though. The position in a sort for a null value would be different than a literal empty String. So, depending on the Object type, I have to make up values which will either come before all other non-null values or after all other non-null values (I don't recall what the natural order of null values are; whether they come first or last. I know when ordering on a SQLcolumn, null values show up last. Hopefully that behavior is consistent here, but that's beside the point here).
> I hope this can be fixed before 1.8.0 is released!
> Jake
--
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[jira] Commented: (BEANUTILS-268) BeanComparator.compare() doesn't
can't handle null values returned by bean properties
Posted by "Niall Pemberton (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/BEANUTILS-268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466633 ]
Niall Pemberton commented on BEANUTILS-268:
-------------------------------------------
Jacob Kjome wrote....
Hi Niall,
I lost one full comment message trying to respond to your comment in Jira and
now I'm trying again and I keep getting system failures when trying to add the
comment. So, I'm emailing you directly. Here's what I tried to write in
Jira...
I see your point, but I think it misses the mark if the root of the problem is
PropertyUtils.getPropterty() throwing the NullPointerException. A "Suitable
Compartor" is irrelevant in this case because the comparator will never have a
chance to be called since the unexpected exception will have already been
thrown.
Having said that, shouldn't all comparators handle null values, not just
"Suitable Comparators"? Lists allow null values. All comparators must account
for this or be brittle by nature.
Please don't close this until we narrow down the problem. If it is
PropertyUtils.getProperty() that causes the problem, then even though all
BeanComparator is doing is delegating to PropertyUtils.getProperty(),
BeanComparator still has to deal with the issue that it can't support beans
that return null property values. If that means fixing
PropertyUtils.getProperty() (actually PropertyUtilsBean.getNestedProperty()),
another BeanUtils class, then so be it. Users of BeanComparator shouldn't have
to concern themselves about how BeanComparator works, just that it does... or
doesn't, as it were.
Jake
> BeanComparator.compare() doesn't can't handle null values returned by bean properties
> -------------------------------------------------------------------------------------
>
> Key: BEANUTILS-268
> URL: https://issues.apache.org/jira/browse/BEANUTILS-268
> Project: Commons BeanUtils
> Issue Type: Bug
> Components: Bean-Collections
> Affects Versions: 1.7.0
> Reporter: Jacob Kjome
>
> I've got a bean that has properties that will, at times, return null values. BeanComparator appears to fail with a NullPointerException. It's difficult to tell exactly where because the exception thrown is a ClassCastException with a message of e.toString(), so all I know is that a NullPointerException happened, not where it happened.
> I suspect that the exception happens inside the compare(Object, Object) method with the call...
> Object value1 = PropertyUtils.getProperty( o1, property );
> Looking into PropertyUtils, and following the path, it seems like the problematic code is in...
> PropertyUtilsBean.getNestedProperty(Object, String)
> That code is rather involved. If I get around to performing a minimal testcase, I'll see if I can narrow down the exception to a particular piece of code. In any case, there's no reason why a bean shouldn't be allowed to return null for a given property.
> My workaround is to add methods for respective properties that are guaranteed to not return null. For instance, if I have a getter called getMyValue(), I create a corresponding method called getMyValueNotNul(). I have to take care with the value it returns, though. The position in a sort for a null value would be different than a literal empty String. So, depending on the Object type, I have to make up values which will either come before all other non-null values or after all other non-null values (I don't recall what the natural order of null values are; whether they come first or last. I know when ordering on a SQLcolumn, null values show up last. Hopefully that behavior is consistent here, but that's beside the point here).
> I hope this can be fixed before 1.8.0 is released!
> Jake
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[jira] Resolved: (BEANUTILS-268) BeanComparator.compare() doesn't
can't handle null values returned by bean properties
Posted by "Jacob Kjome (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/BEANUTILS-268?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jacob Kjome resolved BEANUTILS-268.
-----------------------------------
Resolution: Invalid
> BeanComparator.compare() doesn't can't handle null values returned by bean properties
> -------------------------------------------------------------------------------------
>
> Key: BEANUTILS-268
> URL: https://issues.apache.org/jira/browse/BEANUTILS-268
> Project: Commons BeanUtils
> Issue Type: Bug
> Components: Bean-Collections
> Affects Versions: 1.7.0
> Reporter: Jacob Kjome
>
> I've got a bean that has properties that will, at times, return null values. BeanComparator appears to fail with a NullPointerException. It's difficult to tell exactly where because the exception thrown is a ClassCastException with a message of e.toString(), so all I know is that a NullPointerException happened, not where it happened.
> I suspect that the exception happens inside the compare(Object, Object) method with the call...
> Object value1 = PropertyUtils.getProperty( o1, property );
> Looking into PropertyUtils, and following the path, it seems like the problematic code is in...
> PropertyUtilsBean.getNestedProperty(Object, String)
> That code is rather involved. If I get around to performing a minimal testcase, I'll see if I can narrow down the exception to a particular piece of code. In any case, there's no reason why a bean shouldn't be allowed to return null for a given property.
> My workaround is to add methods for respective properties that are guaranteed to not return null. For instance, if I have a getter called getMyValue(), I create a corresponding method called getMyValueNotNul(). I have to take care with the value it returns, though. The position in a sort for a null value would be different than a literal empty String. So, depending on the Object type, I have to make up values which will either come before all other non-null values or after all other non-null values (I don't recall what the natural order of null values are; whether they come first or last. I know when ordering on a SQLcolumn, null values show up last. Hopefully that behavior is consistent here, but that's beside the point here).
> I hope this can be fixed before 1.8.0 is released!
> Jake
--
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[jira] Commented: (BEANUTILS-268) BeanComparator.compare() doesn't
can't handle null values returned by bean properties
Posted by "Niall Pemberton (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/BEANUTILS-268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12466568 ]
Niall Pemberton commented on BEANUTILS-268:
-------------------------------------------
I don't believe this is an issue for BeanComparator - since all it does is delegate comparing the properties to the Comparator passed in its constructor (or ComparableComparator if none supplied). As the BeanComparator JavaDocs state:
"If you are comparing two beans based on a property that could contain "null" values, a suitable Comparator or ComparatorChain should be supplied in the constructor."
http://tinyurl.com/29wraw
IMO we should close this as an "Invalid" issue.
Niall
> BeanComparator.compare() doesn't can't handle null values returned by bean properties
> -------------------------------------------------------------------------------------
>
> Key: BEANUTILS-268
> URL: https://issues.apache.org/jira/browse/BEANUTILS-268
> Project: Commons BeanUtils
> Issue Type: Bug
> Components: Bean-Collections
> Affects Versions: 1.7.0
> Reporter: Jacob Kjome
>
> I've got a bean that has properties that will, at times, return null values. BeanComparator appears to fail with a NullPointerException. It's difficult to tell exactly where because the exception thrown is a ClassCastException with a message of e.toString(), so all I know is that a NullPointerException happened, not where it happened.
> I suspect that the exception happens inside the compare(Object, Object) method with the call...
> Object value1 = PropertyUtils.getProperty( o1, property );
> Looking into PropertyUtils, and following the path, it seems like the problematic code is in...
> PropertyUtilsBean.getNestedProperty(Object, String)
> That code is rather involved. If I get around to performing a minimal testcase, I'll see if I can narrow down the exception to a particular piece of code. In any case, there's no reason why a bean shouldn't be allowed to return null for a given property.
> My workaround is to add methods for respective properties that are guaranteed to not return null. For instance, if I have a getter called getMyValue(), I create a corresponding method called getMyValueNotNul(). I have to take care with the value it returns, though. The position in a sort for a null value would be different than a literal empty String. So, depending on the Object type, I have to make up values which will either come before all other non-null values or after all other non-null values (I don't recall what the natural order of null values are; whether they come first or last. I know when ordering on a SQLcolumn, null values show up last. Hopefully that behavior is consistent here, but that's beside the point here).
> I hope this can be fixed before 1.8.0 is released!
> Jake
--
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