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custom outputfilter - return empty string

    • 18174
    • 116 Posts
    manu37 Reply #1, 12 years, 4 months ago
    a bug or a feature?
    If my custom outputfilter returns a null string 
    return '';
    the source value seems to be left untouched. This is not logical.
    if my custom outputfilter returns a blank character 
    return ' ';
    the source value is replaced by the blank character.
    If this is a feature this behaviour should be noticed in the rtfm manual.
    regards
    manu
      • 4172
      • 5,888 Posts
      Bruno17 Reply #2, 12 years, 4 months ago
      in modoutputfilter.class.php there is:

      $tmp = $this->modx->runSnippet($m_cmd, $params);
if ($tmp!='') $output = $tmp;


      so, if you return an emtpy string by your output-filter-snippet, the output isn't touched
      But I can't say what's the reason for this line.
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        • 18174
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        manu37 Reply #3, 12 years, 4 months ago
        That's the point.
        For me it is or was a bit confusing.
        IMO if I want to leave the source value untouched I would 
        return $input;

        There is probabely a reason for this behaviour. If this would have been noticed in the manual, it would have saved time of troubleshooting on developing more complex outputfilters.
          • 3749
          • 24,544 Posts
          BobRay Reply #4, 12 years, 4 months ago
          I added a note about this in the docs.
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            • 37059
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            polrbear Reply #5, 10 years, 7 months ago
            One possible kludge of a solution: Set a dummy value and use the :replace output filter to suppress it.

            [[+myvalue:doSomething:replace=`dummyvalue==`]]
              Jason
              • 18174
              • 116 Posts
              manu37 Reply #6, 10 years, 7 months ago
              I can live with the outcome and know possible work arounds. But as I mentioned in #1 it's just not logical to me.
              If I want to leave the source value untouched I would 
              return $input;
              or
              return;
              But for me a nullstring is a value and therefore 
              return '';
              should return a nullstring.
                • 37059
                • 368 Posts
                polrbear Reply #7, 10 years, 7 months ago
                Yeah, +1 on that. I don't see why an output filter should work differently from a standalone snippet or anything else: return null means return null.
                  Jason