如何在Linq中使用xpath来检查元素和属性
本文关键字:检查 元素 属性 xpath Linq | 更新日期: 2023-09-27 18:07:06
我试图连接两个XML文件,连接键有时作为元素出现,但有时作为属性出现,如下面的XML文件所示。如何使用XPath或运算符来解决这个问题?任何其他的解决方案都是非常赞赏的。提前感谢!
文件:<bookstore>
<book>
<bookID>100</bookID>
<name> The cat in the hat </name>
</book>
<book>
<bookID>90</bookID>
<name> another book </name>
</book>
<book>
<bookID>103</bookID>
<name> a new book </name>
</book>
</bookstore>
文件二,在这里连接键bookID是属性:
<bookstore>
<book bookID=100>
<content> story </content>
</book>
<book bookID=90>
<content> fiction </content>
</book>
<book bookID=103>
<content> bio </content>
</book>
我想要的结果是
<result>
<bookInfo>
<bookID>103</bookID>
<name> a new book </name>
<content> bio </content>
<bookInfo>
</result>
我当前基于这个问题的连接操作基于c#中的元素值比较两个xml文档中的元素
var bookInfos =
from a in fileone.Descendants("book")
join b in filetwo.Descendants("book")
on (string)a.Element("bookID") equals (string)b.Element("bookID") //how can I change the Join condition as the key might attributes in any of the two files?
select new XElement("bookInfo",
a.Element("bookID"),
a.Element("name"),
b.Element("content")
);
可以使用空合并操作符??
首先检查是否存在名为"bookID"
的属性,如果不存在,则检查该名称的元素:
var bookInfos =
from a in fileone.Descendants("book")
join b in filetwo.Descendants("book")
on ((string)a.Attribute("bookID") ?? (string)a.Element("bookID")) equals ((string)b.Attribute("bookID") ?? (string)b.Element("bookID"))
select new XElement("bookInfo",
new XElement("bookID", (string)a.Attribute("bookID") ?? (string)a.Element("bookID")),
a.Element("name"),
b.Element("content")
);
您可以在连接条件中表达检索元素或属性的逻辑:
var bookInfos =
from a in fileone.Descendants("book")
let aBookID = (string)a.Element("bookID") ?? (string)a.Attribute("bookID")
join b in filetwo.Descendants("book")
on aBookID equals (string)b.Element("bookID") ?? (string)b.Attribute("bookID")
select new XElement("bookInfo",
aBookID,
a.Element("name"),
b.Element("content")
);
试试这个
on (string)a.Element("bookID") equals (string)(b.Attribute("bookID"))
看到小提琴