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https://issues.apache.org/jira/browse/DIGESTER-143?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Simone Tripodi resolved DIGESTER-143.
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Resolution: Not A Problem
Fix Version/s: 2.2
Sorry if I reply late :(
The CallMethodRule[1] javadoc reports:
??Note that when a constructor is used with paramCount=0, indicating that the
body of the element is to be passed to the target method, an empty element will
cause an empty string to be passed to the target method, not null. And if
automatic type conversion is being applied (ie if the target function takes
something other than a string as a parameter) then the conversion will fail if
the converter class does not accept an empty string as valid input.??
The behavior is documented in the rule class instead of the
Digester#addCallMethod method.
[1]
http://commons.apache.org/digester/apidocs/org/apache/commons/digester/CallMethodRule.html
> Unintuitive, possibly broken behaviour.
> ---------------------------------------
>
> Key: DIGESTER-143
> URL: https://issues.apache.org/jira/browse/DIGESTER-143
> Project: Commons Digester
> Issue Type: Improvement
> Affects Versions: 2.1
> Environment: Linux 64 bits
> Reporter: i30817
> Priority: Minor
> Fix For: 2.2
>
> Attachments: Main.java
>
>
> When one tag is a substring of another tag and both are used as xml patterns,
> such as:
> "rdf:RDF/pgterms:etext/dc:creator"
> "rdf:RDF/pgterms:etext/dc:creator/rdf:Bag/rdf:li" (instances in a collection
> of creators)
> the callback to the first is called once with empty strings ("") as the body
> of the tag if it encounters a instance of the second tag.
> If additionally the first tag has a argument
> "rdf:RDF/pgterms:etext/dc:creator rdf:type="Literal"" and you bind things
> correctly for a two arguments callback with the text body and the argument
> value ("Literal"), the callback of the first will be called with a null
> rdf:type argument and a empty string as the body. You can use this to
> distinguish the bogus callback as a workaround, but requires a additional
> bean method and confusing binding too.
> The best thing would be if these empty strings callback were avoidable. I can
> just test for empty string in the callback, however, i'm trying also to
> create assertions on the xml content (including, no empty strings).
> If the bogus callback must exist, one of the ways to make it obvious and
> distinguishable, would be to use null as the default value, instead of "". No
> xml document will have the computation null value, unless some very strange
> java binding is happening, in which case, you're asking for trouble. "" is
> even worse, because it is common to both domains.
> So RFE:
> 1) Avoid the bogus callback of the smaller xml tree branch if you can.
> 2) if you can't, use null as a default value instead of the indistinguishable
> "".
> 3) if 2) document this behavior in the javadoc and the digester FAQ.
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