根據元素屬性在命令行中拆分xml文件

Question

我擁有具有不同節點和屬性的巨大xml文件。我用grep -c來計算具有特定類型的產品。這裏是我迄今所做的：

grep -c "</products>" products.xml // output : 200023 

grep -c '<product type="cloths"' products.xml // output : 8039 

所以我需要提取與型布料如在new.xml文件樹中的所有產品無所有其他屬性，這樣我可以導入new.xml文件導入數據庫：

<?xml version="1.0"?> 
<!DOCTYPE catalog SYSTEM "catalog.dtd"> 
<catalog> 
    <product type="cloths" product_image="cardigan.jpg"> 
     <catalog_item gender="Men's"> 
     <item_number>QWZ5671</item_number> 
     <price>39.95</price> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     </catalog_item> 
     <catalog_item gender="Women's"> 
     <item_number>RRX9856</item_number> 
     <price>42.50</price> 
     <size description="Small"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Extra Large"> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     </catalog_item> 
    </product> 
</catalog> 

Answer 1

從顯示0​​樣品和應用的問題命令行標記，它看起來像你想要一個純命令行的解決方案。一種選擇是使用xmllint來運行XPath查詢，該查詢只選擇類型爲「布料」的產品。

> xmllint --xpath /catalog/product[@type=\"cloths\"] products.xml 
<product type="cloths" product_image="cardigan.jpg"> 
     <catalog_item gender="Men's"> 
     <item_number>QWZ5671</item_number> 
     <price>39.95</price> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     </catalog_item> 
     <catalog_item gender="Women's"> 
     <item_number>RRX9856</item_number> 
     <price>42.50</price> 
     <size description="Small"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Extra Large"> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     </catalog_item> 
    </product> 

但請注意，這不會產生格式良好的XML文檔。它只是一個包含XPath查詢所選內容的節點集。但是，您可以將其包裝在一些額外的腳本中以生成完整的XML文檔。

printf '<?xml version="1.0"?>\n' > cloths.xml 
printf '<!DOCTYPE catalog SYSTEM "catalog.dtd">\n' >> cloths.xml 
printf '<catalog>\n' >> cloths.xml 
xmllint --xpath /catalog/product[@type=\"cloths\"] products.xml >> cloths.xml 
printf '\n</catalog>\n' >> cloths.xml 

我省略了這些命令之間的錯誤檢查以簡化代碼示例。

您還提到輸入XML文件很大。取決於多大，這種方法在內存消耗方面可能無法很好地擴展。如果這是一個問題，那麼您可能需要採取更多的流式處理方法來解決問題，一次讀取輸入文檔的一小部分並逐步處理。這可能會超出命令行領域和定製編碼領域。流式XML API的一個例子是Java中的StAX。這是一個tutorial。