Question

我正在编写一个程序，从多个外部来源获取经济和社会统计数据，并在数据库中进行采集（用于数据分析）。一些数据以XML格式提供，为了解析它，我需要识别XML文件中的元素/标签以及属性。识别我尝试过使用getAttribute的属性。

问题：虽然getElementsByTagName有效，但getAttribute并不适用。试图检索属性＆＃39;索引＆＃39;的值。从一个单元格返回＆＃34;＆＃34;即使属性指数＆＃39;确实存在于许多细胞元素中。没有错误，只返回没有值。

我花了很多天阅读PHP手册并研究互联网，试图找到解决方案，但没有成功。对getAttribute的返回值进行回显或var_dump显示它始终返回＆＃34;＆＃34;。我没有放入完整的源代码，而是复制了一个更简单的版本，读取下面的XML文件会遇到无法返回属性的问题（在这种情况下是＆＃39; Index＆＃39;属性）。

<?php

// Creates new DOMDocument
$dom = new DOMDocument();
// Loads XML file into DOMDocument
$dom->load('FRED_formatted_list.xml');

// Stores all the instances of the Row tag into $rows
$rows = $dom->getElementsByTagName('Row');

// Iterates through all the instances of the Row tag
foreach($rows as $row) {

// Stores all the instances of the Cell tag into $cells
$cells = $row->getElementsByTagName('Cell');

// Iterates through all the instances of the Cell tag
foreach($cells as $cell) {

    // Checks if the Index attribute exists in the cell tag
    if($cell->hasAttribute('Index')) {
        // Stores the value of any instances of the Index attribute
        $attr = $cell->getAttribute('Index');
        // Prints the value of any instances of the Index attribute to screen
        echo "Value of index attribute: " . $attr . "<br>";

    }
    // Check that the cell tags have been properly identified in the DOM Object
    echo $cell->nodeValue . "<br>";
    // Double checks whether any index values are even found and stored in $attr
    var_dump($attr) . "<br>";
}
}
?>

以下是XML文件的示例，其中显示了属性＆＃39; Index＆＃39;即使getAttributes没有返回，它确实存在：

<Row>
    <Cell><Data ss:Type="String">AAA</Data></Cell>
    <Cell ss:Index="3"><Data ss:Type="String">Board of Governors of the Federal Reserve System (US)</Data></Cell>
    <Cell><Data ss:Type="String">H.15 Selected Interest Rates</Data></Cell>
    <Cell><Data ss:Type="String">Percent</Data></Cell>
    <Cell><Data ss:Type="String">Not Seasonally Adjusted</Data></Cell>
    <Cell><Data ss:Type="String">The Federal Reserve Board has discontinued this series as of October 11, 2016. More information, including possible alternative series, can be found at http://www.federalreserve.gov/feeds/h15.html. </Data></Cell>
</Row>

任何帮助将不胜感激。我将总结解决方案并重新发布以帮助其他人。

Answer 1

在xml中定义名称空间：

<Row xmlns:ss="something">
  <Cell><Data ss:Type="String">AAA</Data></Cell>
  <Cell ss:Index="3"><Data ss:Type="String">Board of Governors of the Federal Reserve System (US)</Data></Cell>
  <Cell><Data ss:Type="String">H.15 Selected Interest Rates</Data></Cell>
  <Cell><Data ss:Type="String">Percent</Data></Cell>
  <Cell><Data ss:Type="String">Not Seasonally Adjusted</Data></Cell>
  <Cell><Data ss:Type="String">The Federal Reserve Board has discontinued this series as of October 11, 2016. More information, including possible alternative series, can be found at http://www.federalreserve.gov/feeds/h15.html. </Data></Cell>
</Row>

尝试使用以下代码获取带有命名空间的属性值：

<?php

  // Creates new DOMDocument
  $dom = new DOMDocument();
  // Loads XML file into DOMDocument
  $dom->load('FRED_formatted_list.xml');

  // Stores all the instances of the Row tag into $rows
  $rows = $dom->getElementsByTagName('Row');
  $attr ='';
  // Iterates through all the instances of the Row tag
  foreach($rows as $row) {

     // Stores all the instances of the Cell tag into $cells
     $cells = $row->getElementsByTagName('Cell');

    // Iterates through all the instances of the Cell tag
    foreach($cells as $cell) {
        // Checks if the Index attribute exists in the cell tag
       if($cell->attributes->getNamedItem('Index')) {
           // Stores the value of any instances of the Index attribute
           $attr = $cell->attributes->getNamedItem('Index')->nodeValue;
           // Prints the value of any instances of the Index attribute to screen
            echo "Value of index attribute: " . $attr . "<br>";

        }
     // Check that the cell tags have been properly identified in the DOM Object
     echo $cell->nodeValue . "<br>";
     // Double checks whether any index values are even found and stored in $attr
     var_dump($attr) . "<br>";


   }

}

Answer 2

经过进一步的研究后，我发现其他人遇到了这个问题，并设法解决了这个问题。属性＆＃39;索引＆＃39;在XML单元格标签/元素中使用＆s; ss预先修复：＆＃39; （根据<Cell ss:Index="3"><Data ss:Type="String">上面的XML文件摘录）。为了让getAttribute能够解决问题：＆＃39; ss：＆＃39;需要包括在内正确的代码将是getAttribute('ss:Index')而不是 getAttribute('Index')
我不完全理解getAttribute如何识别某个属性，但可能是搜索一串前面带有空格的连续字符，因此＆＃39; ss：＆＃39;需要包括在内。

DOM对象的getAttribute没有返回属性

2 个答案: