duanfan5012 2018-07-03 18:42
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PHP - 删除XML空节点

I found this code to remove empty nodes from and XML file but it isn't working correctly. It leaves an empty node that really needs to be removed. Yes, it is empty, just white space in it.

$domxml = new DOMDocument('1.0');
$domxml->preserveWhiteSpace = false;
$domxml->formatOutput = true;
$domxml->loadXML($this->response);
$this->response = $domxml->saveXML($domxml->documentElement);

Anyone know of a better way to do this?

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  • dongzhenge2014 2018-07-04 08:13
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    In other words you would like to remove any element node that has no text content, no attribute, no children with text content or attributes and have a parent element node (are not the document element).

    Here is an Xpath function normalize-space() that converts any whitespace sequences to single spaces and strips them from the start/end. Any whitespace only content will result in an empty string.

    Xpath

    //* fetches any element node in the document in a list. You just need to add conditions.

    • Has no text content
      normalize-space(.) = ""
    • No attributes
      not(@*)
    • No descendant node with content (includes comments, ...)
      not(.//node()[normalize-space(.) != ""])
    • No descendant element nodes with attributes
      not(.//*[@*])
    • Has a parent element node
      parent::*

    Put together:

    $xml = <<<'XML'
    <foo>
      <bar></bar>
      <bar>123</bar>
      <bar foo="123"></bar>
      <bar><foo>   </foo></bar>
      <bar><!-- test --></bar>
    </foo>
    XML;
    
    $document = new DOMDocument();
    $document->preserveWhiteSpace = FALSE;
    $document->formatOutput = TRUE; 
    $document->loadXml($xml);
    $xpath = new DOMXpath($document);
    
    $expression = 
      '//*[
        normalize-space(.) = "" and 
        not(@*) and  
        not(.//node()[normalize-space(.) != ""]) and 
        not(.//*[@*]) and
        parent::*
      ]';
    
    $nodes = $xpath->evaluate($expression);
    for ($i = $nodes->length - 1; $i >= 0; $i--) {
      $nodes[$i]->parentNode->removeChild($nodes[$i]);
    }
    
    echo $document->saveXml();
    

    Output:

    <?xml version="1.0"?>
    <foo>
      <bar>123</bar>
      <bar foo="123"/>
      <bar>
        <!-- test -->
      </bar>
    </foo>
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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