Details

    • Type: Improvement Improvement
    • Status: Closed
    • Priority: Minor Minor
    • Resolution: Not a Problem
    • Affects Version/s: 2.1
    • Fix Version/s: 3.0
    • Labels:
      None
    • Environment:

      Linux 64 bits

      Description

      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.

        Activity

        Hide
        Simone Tripodi added a comment -

        Can you provide please a use case? Thanks in advance!

        Show
        Simone Tripodi added a comment - Can you provide please a use case? Thanks in advance!
        Hide
        i30817 added a comment -

        I attach a minimal test case; that i think is what you meant. The use case i already gave: assert that a xml catalog doens't have empty strings in specific tags, where the tags follow this format.

        Show
        i30817 added a comment - I attach a minimal test case; that i think is what you meant. The use case i already gave: assert that a xml catalog doens't have empty strings in specific tags, where the tags follow this format.
        Hide
        i30817 added a comment -

        testcase

        Show
        i30817 added a comment - testcase
        Hide
        Simone Tripodi added a comment -

        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

        Show
        Simone Tripodi added a comment - 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
        Hide
        Simone Tripodi added a comment -

        included in Apache Commons Digester 3.0 release

        Show
        Simone Tripodi added a comment - included in Apache Commons Digester 3.0 release

          People

          • Assignee:
            Simone Tripodi
            Reporter:
            i30817
          • Votes:
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            Watchers:
            1 Start watching this issue

            Dates

            • Created:
              Updated:
              Resolved:

              Development