Question

I have an XML document I generate on the fly, and I need a function to eliminate any duplicate nodes from it.

My function looks like:

declare function local:start2() {     let $data := local:scan_books()     return <books>{$data}</books> }; 

Sample output is:

<books>   <book>     <title>XML in 24 hours</title>     <author>Some Guy</author>     </book>   <book>     <title>XML in 24 hours</title>     <author>Some Guy</author>     </book> </books> 

I want just the one entry in my books root tag, and there are other tags, like say pamphlet in there too that need to have duplicates removed. Any ideas?

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Updated following comments. By unique nodes, I mean remove multiple occurrences of nodes that have the exact same content and structure.

Answer 1

A simpler and more direct one-liner XPath solution:

Just use the following XPath expression:

  /*/book         [index-of(/*/book/title,                    title                  )                   [1]         ] 

When applied, for example, on the following XML document:

<books>     <book>         <title>XML in 24 hours</title>         <author>Some Guy</author>     </book>     <book>         <title>Food in Seattle</title>         <author>Some Guy2</author>     </book>     <book>         <title>XML in 24 hours</title>         <author>Some Guy</author>     </book>     <book>         <title>Food in Seattle</title>         <author>Some Guy2</author>     </book>     <book>         <title>How to solve XPAth Problems</title>         <author>Me</author>     </book> </books> 

the above XPath expression selects correctly the following nodes:

<book>     <title>XML in 24 hours</title>     <author>Some Guy</author> </book> <book>     <title>Food in Seattle</title>     <author>Some Guy2</author> </book> <book>     <title>How to solve XPAth Problems</title>     <author>Me</author> </book> 

The explanation is simple: For every book, select only one of its occurences — such that its index in all-books is the same as the first index of its title in all-titles.