give value to node value in xquery marklogic - xquery

Question

I have a xml format in a variable like below
let $node := <root><a/></root>
I want to give value to the <a>.
I am using marklogic 6 and i want to run this xquery in qconsole of marklogic

Answer 1

Depending on what you want to do with $node, and where you got the value of $node in the first place, there are a few options. It basically comes down to doing an in-memory update, or a database update.
The database update is usefull if you want to preserve the change for other queries, but that involves storing, and retrieving things from database. MarkLogic doesn't support the XQuery Update syntax, but it does allow you to store things. You can use functions like xdmp:document-insert to update complete documents, or functions like xdmp:node-insert-child to manipulate documents stored in database.
For in memory updates, you will have to reconstruct the node tree manually. You can use the in-memory-update library to which dirkk refers, or do it yourself. A simple way would be:
let $node := <root><a/></root>
let $a-value := "a value"
return
<root><a>{$a-value}</a></root>
Or more generically:
let $node := <root><a/></root>
let $a-value := "a value"
return
element { node-name($node) } {
$node/#*,
for $child in $node/node()
return
typeswitch ($child)
case element(a) return
element { node-name($node) } {
$node/#*,
$a-value
}
default return $child
}
HTH!

Answer 2

The general idea is to transform the XML into the shape you want. In the simplest case you can hard-code everything:
let $node := <root><a/></root>
return <root><a>hello world</a></root>
Of course you probably want to make things more dynamic:
let $node := <root><a/></root>
let $value := "hello world"
return <root><a>{ $value }</a></root>
Or
let $node := <root><a/></root>
let $value := "hello world"
return element { node-name($node) } {
<a>{ $value }</a>
}
Or maybe
let $node := <root><a/></root>
let $value := "hello world"
return element { node-name($node) } {
$node/#*,
for $n in $node/node() return typeswitch($n)
case element(a) return element { node-name($n) } { $n/#*, $value }
default return $n
}
From there you can get into recursive typeswitch forms, or XSLT: see http://docs.marklogic.com/guide/app-dev/typeswitch for more.