使用 linq 选择子元素

Question

您好，我几天前刚刚开始研究 LINQ-XML，想知道我是否做错了什么，或者根本不可能做到这一点。我已经搜索过了，没有任何与我相关的问题，我现在已经闲逛了一下。

XML：

<catalog>
<product description="Cardigan Sweater" 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>

和查询：

        var query =
        from size in
            (
                from catalogItem in cardigan.Descendants("catalog_item")
                where catalogItem.Attribute("gender").Value == "Men's"
                select catalogItem.Descendants("size")
            )
        select size.Elements("color_swatch");

这基本上为我提供了男装的所有 color_swatch，但我一直在尝试查看是否可以获得男装大号的所有 color_swatch。

提前致谢。

Answer 1

只需将您的查询更改为

    var query =
    from size in
        (
            from catalogItem in cardigan.Descendants("catalog_item")
            where catalogItem.Attribute("gender").Value == "Men's"
            select catalogItem.Descendants("size")
        )
    where size.Attribute("description") == "Large"
    select size.Elements("color_swatch");

“这”即可工作，因为您首先获得适用于男士的所有“尺码”商品，然后从该列表中筛选出仅抓取“大号”商品的商品。

Answer 2

好吧，我又胡思乱想了一些……我明白了……

var query =        
from catalogItem in cardigan.Descendants("catalog_item")
where catalogItem.Attribute("gender").Value == "Men's"
from size in catalogItem.Descendants("size")
where size.Attribute("description").Value == "Large"
select size.Elements("color_swatch");

花了大约 8 个小时，但我明白了！

我基本上得到了一些复杂的 xml 示例来进行处理。我想这就是你学习的方式。 :)

谢谢大家:)