C# What query language to specify in rule to pull out the two book nodes

问题

<?xml version="1.0" encoding="ISO-8859-1"?>
  <bookstore>

      <book category="COOKING"> 
        <title lang="en">Everyday Italian</title>
        <author>Giada De Laurentiis</author>    
        <year>2005</year>
       <price>30.00</price>
      </book>

      <book category="CHILDREN">
       <title lang="en">Harry Potter</title>
       <author>J K. Rowling</author>
       <year>2005</year>
       <price>29.99</price>
      </book>

      <book category="WEB">
       <title lang="en">XQuery Kick Start</title>
       <author>James McGovern</author>
       <author>Per Bothner</author>
       <author>Kurt Cagle</author>
       <author>James Linn</author>
       <author>Vaidyanathan Nagarajan</author>
       <year>2003</year>
       <price>49.99</price>
      </book>

      <book category="WEB">
       <title lang="en">Learning XML</title>
       <author>Erik T. Ray</author>
       <year>2003</year>
       <price>39.95</price>
      </book>

    </bookstore>

Hi, Currently, I have a rules based system, where incoming xml messages are matched against a rule, and if the rule hits, the packet is processed. To get a match I use xpath to select individual values in the xml, and I specify these in the rule as combined xpath:regexp expressions, something like this.

/bookstore/book[1]/ title: (.+)

For example the above would match against the "Everyday Italian"

But I'm trying to find a query or perhaps a new query language expression which will allow me to select all the book nodes for the above classic msdn docs book.xml, such that if I specify the query expression in the rule, I can lift it using a parser, and use it directly against the xml file to pull out the books node.

I don't know if xpath can do it. I was looking at XQuery, but it seems wordy. XSLT could probably do it, but it's wordy. Any ideas.

Is their a simple way of specifying an expression such that it would lift all book nodes, or say 1 and 2, or 1st and 3rd.

Thanks. Bob.

回答1:

The following questions, which of a different design, answered it indirectly.

XPath Node Select

回答2:

using xquery and flwor:

nicholas@mordor:~/flwor/position$ 
nicholas@mordor:~/flwor/position$ basex position.xq 
<book category="children">
  <title lang="en">Harry Potter</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>
<book category="web">
  <title lang="en">XQuery Kick Start</title>
  <author>James McGovern</author>
  <author>Per Bothner</author>
  <author>Kurt Cagle</author>
  <author>James Linn</author>
  <author>Vaidyanathan Nagarajan</author>
  <year>2003</year>
  <price>49.99</price>
</book>nicholas@mordor:~/flwor/position$ 
nicholas@mordor:~/flwor/position$ 
nicholas@mordor:~/flwor/position$ cat position.xq 

xquery version "3.1";

let $doc := doc("bookstore.xml")
let $books := $doc/bookstore/book

for $book at $p in $books 
where $p gt 1 and $p lt 4
return $book
nicholas@mordor:~/flwor/position$ 
nicholas@mordor:~/flwor/position$ cat bookstore.xml 
<bookstore>
  <book category="cooking">
    <title lang="en">Everyday Italian</title>
    <author>Giada De Laurentiis</author>
    <year>2005</year>
    <price>30.00</price>
  </book>
  <book category="children">
    <title lang="en">Harry Potter</title>
    <author>J K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">XQuery Kick Start</title>
    <author>James McGovern</author>
    <author>Per Bothner</author>
    <author>Kurt Cagle</author>
    <author>James Linn</author>
    <author>Vaidyanathan Nagarajan</author>
    <year>2003</year>
    <price>49.99</price>
  </book>
  <book category="web">
    <title lang="en">Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>
</bookstore>nicholas@mordor:~/flwor/position$ 

the where clause can find the position of each book node, and just return specific nodes.

来源：https://stackoverflow.com/questions/1493639/c-sharp-what-query-language-to-specify-in-rule-to-pull-out-the-two-book-nodes