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Posted to issues@commons.apache.org by "Johannes Stelzer (JIRA)" <ji...@apache.org> on 2011/06/07 12:09:58 UTC
[jira] [Created] (JXPATH-151) a != null results in false!
a != null results in false!
---------------------------
Key: JXPATH-151
URL: https://issues.apache.org/jira/browse/JXPATH-151
Project: Commons JXPath
Issue Type: Bug
Affects Versions: 1.3
Environment: windows oracle jvm 1.6_25
Reporter: Johannes Stelzer
Priority: Blocker
Comparing an vaule to null using unequals(!=) yields false!
Example code:
public static void main(String[] args) {
Map<String, Integer> m = new HashMap<String, Integer>();
m.put("a", 1);
m.put("b", null);
m.put("c", 1);
JXPathContext c = JXPathContext.newContext(m);
System.out.println(c.getValue("a != b") + " should be true");
System.out.println(c.getValue("a != c") + " should be false");
System.out.println(c.getValue("a = b") + " should be false");
System.out.println(c.getValue("a = c") + " should be true");
System.out.println(c.getValue("not(a = b)") + " should be true");
System.out.println(c.getValue("not(a = c)") + " should be false");
}
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[jira] [Resolved] (JXPATH-151) null handling is inconsistent
Posted by "Matt Benson (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Matt Benson resolved JXPATH-151.
--------------------------------
Resolution: Fixed
Committed revision 1133499.
> null handling is inconsistent
> -----------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
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[jira] [Updated] (JXPATH-151) a != null results in false!
Posted by "Johannes Stelzer (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Johannes Stelzer updated JXPATH-151:
------------------------------------
Description:
Comparing a vaule to null using unequals (!=) yields false!
{quote}
Map<String, Integer> m = new HashMap<String, Integer>();
m.put("a", 1);
m.put("b", null);
m.put("c", 1);
JXPathContext c = JXPathContext.newContext(m);
System.out.println(c.getValue("a != b") + " should be true");
System.out.println(c.getValue("a != c") + " should be false");
System.out.println(c.getValue("a = b") + " should be false");
System.out.println(c.getValue("a = c") + " should be true");
System.out.println(c.getValue("not(a = b)") + " should be true");
System.out.println(c.getValue("not(a = c)") + " should be false");
{quote}
Output using 1.3:
{color:red} false should be true{color}
false should be false
false should be false
true should be true
true should be true
false should be false
In 1.2 it works correctly!
was:
Comparing a vaule to null using unequals (!=) yields false!
{{quote}}
Map<String, Integer> m = new HashMap<String, Integer>();
m.put("a", 1);
m.put("b", null);
m.put("c", 1);
JXPathContext c = JXPathContext.newContext(m);
System.out.println(c.getValue("a != b") + " should be true");
System.out.println(c.getValue("a != c") + " should be false");
System.out.println(c.getValue("a = b") + " should be false");
System.out.println(c.getValue("a = c") + " should be true");
System.out.println(c.getValue("not(a = b)") + " should be true");
System.out.println(c.getValue("not(a = c)") + " should be false");
{{quote}}
Output using 1.3:
{color:red} false should be true{color}
false should be false
false should be false
true should be true
true should be true
false should be false
In 1.2 it works correctly!
> a != null results in false!
> ---------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (!=) yields false!
> {quote}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {quote}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
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[jira] [Issue Comment Edited] (JXPATH-151) null handling is
inconsistent
Posted by "Matt Benson (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13046117#comment-13046117 ]
Matt Benson edited comment on JXPATH-151 at 6/8/11 6:19 PM:
------------------------------------------------------------
Setting up a similar map to what you have described, and accessing via a bean property I still found the errors you describe. This issue was fairly difficult to triage, but my final diagnosis is that it is indicative of a bug. It is interesting to note that the {{value\[@name='a'\] != value\[@name='b\]}} approach succeeded, and of course the two approaches _should_ yield equivalent results for any key conforming to {{QName}} restrictions. I would still consider it dangerous to depend on {{null}} values in JXPath, however. For example, if you add a mapping of {{"d":0}} to your map, you will find that {{value\[@name='d'\] = value\[@name='b'\]}} because the fact that {{d}} refers to a numeric type forces the conversion of {{b}}'s {{null}} value to a number, {{0.0}}. XPath is tricky this way, and JXPath, dealing with types unknown to the XPath specification, only becomes trickier.
Having said all that, and to return to the issue at hand, I found that certain existing JXPath tests assert that it should be possible to get a {{null}} value from the expression {{bean.nullProperty}}, but that iterating pointers from the expression {{bean.nullProperty\[1\]}} should yield no results. But this assigns a Java-centric meaning to XPath's {{\[1\]}} test, and it is my judgment that this is overstepping given that Javadoc for relevant methods states that non-Collection items should be treated as having length 1. Making the conscious decision to _change_ an existing unit test is not a decision to make lightly, but in this case my opinion is that it is warranted.
was (Author: mbenson):
Setting up a similar map to what you have described, and accessing via a bean property I still found the errors you describe. This issue was fairly difficult to triage, but my final diagnosis is that it is indicative of a bug. It is interesting to note that the {{value\[@name='a'\] != value\[@name='b\]}} approach succeeded, and of course the two approaches _should_ yield equivalent results for any key conforming to {{QName}} restrictions. I would still consider it dangerous to depend on {{null}} values in JXPath, however. For example, if you add a mapping of {{"d":0}} to your map, you will find that {{value\[@name='d'\] = value\[@name='b'\]}} because the fact that {{d}} refers to a numeric type forces the conversion of {{b}}'s {{null}} value to a number, {{0.0}}. XPath is tricky this way, and JXPath, dealing with types unknown to the XPath specification only becomes trickier.
Having said all that, and to return to the issue at hand, I found that certain existing JXPath tests assert that it should be possible to get a {{null}} value from the expression {{bean.nullProperty}}, but that iterating pointers from the expression {{bean.nullProperty\[1\]}} should yield no results. But this assigns a Java-centric meaning to XPath's {{\[1\]}} test, and it is my judgment that this is overstepping given that Javadoc for relevant methods states that non-Collection items should be treated as having length 1. Making the conscious decision to _change_ an existing unit test is not a decision to make lightly, but in this case my opinion is that it is warranted.
> null handling is inconsistent
> -----------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
--
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[jira] [Updated] (JXPATH-151) null handling is inconsistent
Posted by "Matt Benson (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Matt Benson updated JXPATH-151:
-------------------------------
Summary: null handling is inconsistent (was: a != null results in false!)
> null handling is inconsistent
> -----------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
--
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For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Updated] (JXPATH-151) a != null results in false!
Posted by "Johannes Stelzer (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Johannes Stelzer updated JXPATH-151:
------------------------------------
Description:
Comparing a vaule to null using unequals (\!=) yields false!
{noformat}
Map<String, Integer> m = new HashMap<String, Integer>();
m.put("a", 1);
m.put("b", null);
m.put("c", 1);
JXPathContext c = JXPathContext.newContext(m);
System.out.println(c.getValue("a != b") + " should be true");
System.out.println(c.getValue("a != c") + " should be false");
System.out.println(c.getValue("a = b") + " should be false");
System.out.println(c.getValue("a = c") + " should be true");
System.out.println(c.getValue("not(a = b)") + " should be true");
System.out.println(c.getValue("not(a = c)") + " should be false");
{noformat}
Output using 1.3:
{color:red} false should be true{color}
false should be false
false should be false
true should be true
true should be true
false should be false
In 1.2 it works correctly!
was:
Comparing a vaule to null using unequals (!=) yields false!
{quote}
Map<String, Integer> m = new HashMap<String, Integer>();
m.put("a", 1);
m.put("b", null);
m.put("c", 1);
JXPathContext c = JXPathContext.newContext(m);
System.out.println(c.getValue("a != b") + " should be true");
System.out.println(c.getValue("a != c") + " should be false");
System.out.println(c.getValue("a = b") + " should be false");
System.out.println(c.getValue("a = c") + " should be true");
System.out.println(c.getValue("not(a = b)") + " should be true");
System.out.println(c.getValue("not(a = c)") + " should be false");
{quote}
Output using 1.3:
{color:red} false should be true{color}
false should be false
false should be false
true should be true
true should be true
false should be false
In 1.2 it works correctly!
> a != null results in false!
> ---------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
--
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For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (JXPATH-151) null handling is inconsistent
Posted by "Matt Benson (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13046117#comment-13046117 ]
Matt Benson commented on JXPATH-151:
------------------------------------
Setting up a similar map to what you have described, and accessing via a bean property I still found the errors you describe. This issue was fairly difficult to triage, but my final diagnosis is that it is indicative of a bug. It is interesting to note that the {{value[@name='a'] != value[@name='b]}} approach succeeded, although I would still consider it dangerous to depend on {{null}} values in JXPath. For example, if you add a mapping of {{"d":0}} to your map, you will find that {{value[@name='d'] = value[@name='b']}} because the fact that {{d}} refers to a numeric type forces the conversion of {{b}}'s {{null}} value to a number, {{0.0}}. XPath is tricky this way, and JXPath, dealing with types unknown to the XPath specification only becomes trickier.
Having said all that, and to return to the issue at hand, I found that certain existing JXPath tests assert that it should be possible to get a {{null}} value from the expression {{bean.nullProperty}}, but that iterating pointers from the expression {{bean.nullProperty[1]}} should yield no results. But this assigns a Java-centric meaning to XPath's {{[1]}} test, and it is my judgment that this is overstepping given that Javadoc for relevant methods states that non-Collection items should be treated as having length 1. Making the conscious decision to _change_ an existing unit test is not a decision to make lightly, but in this case my opinion is that it is warranted.
> null handling is inconsistent
> -----------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
--
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[jira] [Commented] (JXPATH-151) a != null results in false!
Posted by "Matt Benson (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13045451#comment-13045451 ]
Matt Benson commented on JXPATH-151:
------------------------------------
Typically JXPath isn't expected to work with a {{Map}}/{{Object[]}}/{{Collection}} as its root context object, although I note your comment that this works in 1.2. Can you try adding your map to a simple object wrapper (e.g. {{org.apache.commons.lang.mutable.MutableObject}}) and report back the results of {{"value/a != value/b"}}, and {{"value\[@name='a'\] != value\[@name='b'\]"}} ?
> a != null results in false!
> ---------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
--
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[jira] [Updated] (JXPATH-151) a != null results in false!
Posted by "Johannes Stelzer (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Johannes Stelzer updated JXPATH-151:
------------------------------------
Description:
Comparing a vaule to null using unequals (!=) yields false!
{{quote}}
Map<String, Integer> m = new HashMap<String, Integer>();
m.put("a", 1);
m.put("b", null);
m.put("c", 1);
JXPathContext c = JXPathContext.newContext(m);
System.out.println(c.getValue("a != b") + " should be true");
System.out.println(c.getValue("a != c") + " should be false");
System.out.println(c.getValue("a = b") + " should be false");
System.out.println(c.getValue("a = c") + " should be true");
System.out.println(c.getValue("not(a = b)") + " should be true");
System.out.println(c.getValue("not(a = c)") + " should be false");
{{quote}}
Output using 1.3:
{color:red} false should be true{color}
false should be false
false should be false
true should be true
true should be true
false should be false
In 1.2 it works correctly!
was:
Comparing an vaule to null using unequals(!=) yields false!
Example code:
public static void main(String[] args) {
Map<String, Integer> m = new HashMap<String, Integer>();
m.put("a", 1);
m.put("b", null);
m.put("c", 1);
JXPathContext c = JXPathContext.newContext(m);
System.out.println(c.getValue("a != b") + " should be true");
System.out.println(c.getValue("a != c") + " should be false");
System.out.println(c.getValue("a = b") + " should be false");
System.out.println(c.getValue("a = c") + " should be true");
System.out.println(c.getValue("not(a = b)") + " should be true");
System.out.println(c.getValue("not(a = c)") + " should be false");
}
> a != null results in false!
> ---------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (!=) yields false!
> {{quote}}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {{quote}}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
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[jira] [Issue Comment Edited] (JXPATH-151) null handling is
inconsistent
Posted by "Matt Benson (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13046117#comment-13046117 ]
Matt Benson edited comment on JXPATH-151 at 6/8/11 6:16 PM:
------------------------------------------------------------
Setting up a similar map to what you have described, and accessing via a bean property I still found the errors you describe. This issue was fairly difficult to triage, but my final diagnosis is that it is indicative of a bug. It is interesting to note that the {{value\[@name='a'\] != value\[@name='b\]}} approach succeeded, although I would still consider it dangerous to depend on {{null}} values in JXPath. For example, if you add a mapping of {{"d":0}} to your map, you will find that {{value\[@name='d'\] = value\[@name='b'\]}} because the fact that {{d}} refers to a numeric type forces the conversion of {{b}}'s {{null}} value to a number, {{0.0}}. XPath is tricky this way, and JXPath, dealing with types unknown to the XPath specification only becomes trickier.
Having said all that, and to return to the issue at hand, I found that certain existing JXPath tests assert that it should be possible to get a {{null}} value from the expression {{bean.nullProperty}}, but that iterating pointers from the expression {{bean.nullProperty\[1\]}} should yield no results. But this assigns a Java-centric meaning to XPath's {{\[1\]}} test, and it is my judgment that this is overstepping given that Javadoc for relevant methods states that non-Collection items should be treated as having length 1. Making the conscious decision to _change_ an existing unit test is not a decision to make lightly, but in this case my opinion is that it is warranted.
was (Author: mbenson):
Setting up a similar map to what you have described, and accessing via a bean property I still found the errors you describe. This issue was fairly difficult to triage, but my final diagnosis is that it is indicative of a bug. It is interesting to note that the {{value[@name='a'] != value[@name='b]}} approach succeeded, although I would still consider it dangerous to depend on {{null}} values in JXPath. For example, if you add a mapping of {{"d":0}} to your map, you will find that {{value[@name='d'] = value[@name='b']}} because the fact that {{d}} refers to a numeric type forces the conversion of {{b}}'s {{null}} value to a number, {{0.0}}. XPath is tricky this way, and JXPath, dealing with types unknown to the XPath specification only becomes trickier.
Having said all that, and to return to the issue at hand, I found that certain existing JXPath tests assert that it should be possible to get a {{null}} value from the expression {{bean.nullProperty}}, but that iterating pointers from the expression {{bean.nullProperty[1]}} should yield no results. But this assigns a Java-centric meaning to XPath's {{[1]}} test, and it is my judgment that this is overstepping given that Javadoc for relevant methods states that non-Collection items should be treated as having length 1. Making the conscious decision to _change_ an existing unit test is not a decision to make lightly, but in this case my opinion is that it is warranted.
> null handling is inconsistent
> -----------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
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[jira] [Issue Comment Edited] (JXPATH-151) null handling is
inconsistent
Posted by "Matt Benson (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/JXPATH-151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13046117#comment-13046117 ]
Matt Benson edited comment on JXPATH-151 at 6/8/11 6:18 PM:
------------------------------------------------------------
Setting up a similar map to what you have described, and accessing via a bean property I still found the errors you describe. This issue was fairly difficult to triage, but my final diagnosis is that it is indicative of a bug. It is interesting to note that the {{value\[@name='a'\] != value\[@name='b\]}} approach succeeded, and of course the two approaches _should_ yield equivalent results for any key conforming to {{QName}} restrictions. I would still consider it dangerous to depend on {{null}} values in JXPath, however. For example, if you add a mapping of {{"d":0}} to your map, you will find that {{value\[@name='d'\] = value\[@name='b'\]}} because the fact that {{d}} refers to a numeric type forces the conversion of {{b}}'s {{null}} value to a number, {{0.0}}. XPath is tricky this way, and JXPath, dealing with types unknown to the XPath specification only becomes trickier.
Having said all that, and to return to the issue at hand, I found that certain existing JXPath tests assert that it should be possible to get a {{null}} value from the expression {{bean.nullProperty}}, but that iterating pointers from the expression {{bean.nullProperty\[1\]}} should yield no results. But this assigns a Java-centric meaning to XPath's {{\[1\]}} test, and it is my judgment that this is overstepping given that Javadoc for relevant methods states that non-Collection items should be treated as having length 1. Making the conscious decision to _change_ an existing unit test is not a decision to make lightly, but in this case my opinion is that it is warranted.
was (Author: mbenson):
Setting up a similar map to what you have described, and accessing via a bean property I still found the errors you describe. This issue was fairly difficult to triage, but my final diagnosis is that it is indicative of a bug. It is interesting to note that the {{value\[@name='a'\] != value\[@name='b\]}} approach succeeded, although I would still consider it dangerous to depend on {{null}} values in JXPath. For example, if you add a mapping of {{"d":0}} to your map, you will find that {{value\[@name='d'\] = value\[@name='b'\]}} because the fact that {{d}} refers to a numeric type forces the conversion of {{b}}'s {{null}} value to a number, {{0.0}}. XPath is tricky this way, and JXPath, dealing with types unknown to the XPath specification only becomes trickier.
Having said all that, and to return to the issue at hand, I found that certain existing JXPath tests assert that it should be possible to get a {{null}} value from the expression {{bean.nullProperty}}, but that iterating pointers from the expression {{bean.nullProperty\[1\]}} should yield no results. But this assigns a Java-centric meaning to XPath's {{\[1\]}} test, and it is my judgment that this is overstepping given that Javadoc for relevant methods states that non-Collection items should be treated as having length 1. Making the conscious decision to _change_ an existing unit test is not a decision to make lightly, but in this case my opinion is that it is warranted.
> null handling is inconsistent
> -----------------------------
>
> Key: JXPATH-151
> URL: https://issues.apache.org/jira/browse/JXPATH-151
> Project: Commons JXPath
> Issue Type: Bug
> Affects Versions: 1.3
> Environment: windows oracle jvm 1.6_25
> Reporter: Johannes Stelzer
> Priority: Blocker
>
> Comparing a vaule to null using unequals (\!=) yields false!
> {noformat}
> Map<String, Integer> m = new HashMap<String, Integer>();
> m.put("a", 1);
> m.put("b", null);
> m.put("c", 1);
> JXPathContext c = JXPathContext.newContext(m);
> System.out.println(c.getValue("a != b") + " should be true");
> System.out.println(c.getValue("a != c") + " should be false");
> System.out.println(c.getValue("a = b") + " should be false");
> System.out.println(c.getValue("a = c") + " should be true");
> System.out.println(c.getValue("not(a = b)") + " should be true");
> System.out.println(c.getValue("not(a = c)") + " should be false");
> {noformat}
> Output using 1.3:
> {color:red} false should be true{color}
> false should be false
> false should be false
> true should be true
> true should be true
> false should be false
> In 1.2 it works correctly!
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