Difference between revisions of "XQuery Recipes"
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(Added Leo's function (Thanks to Leo & Huib) from https://mailman.uni-konstanz.de/pipermail/basex-talk/2011-January/001034.html) |
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Line 19: | Line 19: | ||
</pre> | </pre> | ||
+ | == Transform List to Tree == | ||
+ | This snippet transform a ''flat'' list of elements with <code>parentId</code>-references to a nested list. | ||
+ | |||
+ | <pre class="brush:xquery"> | ||
+ | declare function local:link($entries as node()*, $id as xs:string) { | ||
+ | let $entry := $entries[@id eq $id], | ||
+ | $children := $entries[@parentId eq $id] | ||
+ | return element entry { | ||
+ | $entry/@*, | ||
+ | for $child in $children | ||
+ | return local:link($entries, $child/@id) | ||
+ | } | ||
+ | }; | ||
+ | |||
+ | let $entries := | ||
+ | <entries> | ||
+ | <entry id="entry1" /> | ||
+ | <entry id="entry2" parentId="entry1" /> | ||
+ | <entry id="entry3" parentId="entry1" /> | ||
+ | <entry id="entry4" parentId="entry2" /> | ||
+ | <entry id="entry5" parentId="entry2" /> | ||
+ | <entry id="entry6" parentId="entry3" /> | ||
+ | <entry id="entry7" parentId="entry3" /> | ||
+ | </entries> | ||
+ | return local:link($entries/entry, 'entry1') | ||
+ | </pre> | ||
+ | results in | ||
+ | <pre class="brush:xml"> | ||
+ | <entry id="entry1"> | ||
+ | <entry id="entry2" parentId="entry1"> | ||
+ | <entry id="entry4" parentId="entry2"/> | ||
+ | <entry id="entry5" parentId="entry2"/> | ||
+ | </entry> | ||
+ | <entry id="entry3" parentId="entry1"> | ||
+ | <entry id="entry6" parentId="entry3"/> | ||
+ | <entry id="entry7" parentId="entry3"/> | ||
+ | </entry> | ||
+ | </entry> | ||
+ | </pre> | ||
[[Category:XQuery]] | [[Category:XQuery]] |
Revision as of 23:32, 24 January 2011
This page contains code snippets that mainly originate from our basex-talk mailing list.
Computed Elements
Returns dynamically named elements:
let $root := "element" let $value := "hi" let $contents := <foo>Bar!</foo> return element { $root } { attribute { "about" } { $value }, $contents }
The result is an XML fragment with <element>
as root node:
<element about="hi"> <foo>Bar!</foo> </element>
Transform List to Tree
This snippet transform a flat list of elements with parentId
-references to a nested list.
declare function local:link($entries as node()*, $id as xs:string) { let $entry := $entries[@id eq $id], $children := $entries[@parentId eq $id] return element entry { $entry/@*, for $child in $children return local:link($entries, $child/@id) } }; let $entries := <entries> <entry id="entry1" /> <entry id="entry2" parentId="entry1" /> <entry id="entry3" parentId="entry1" /> <entry id="entry4" parentId="entry2" /> <entry id="entry5" parentId="entry2" /> <entry id="entry6" parentId="entry3" /> <entry id="entry7" parentId="entry3" /> </entries> return local:link($entries/entry, 'entry1')
results in
<entry id="entry1"> <entry id="entry2" parentId="entry1"> <entry id="entry4" parentId="entry2"/> <entry id="entry5" parentId="entry2"/> </entry> <entry id="entry3" parentId="entry1"> <entry id="entry6" parentId="entry3"/> <entry id="entry7" parentId="entry3"/> </entry> </entry>