Finding unique nodes with xslt - xslt

I have an xml document that contains some "Item" elements with ids. I want to make a list of the unique Item ids. The Item elements are not in a list though - they can be at any depth within the xml document - for example:
<Node>
<Node>
<Item id="1"/>
<Item id="2"/>
</Node>
<Node>
<Item id="1"/>
<Node>
<Item id="3"/>
</Node>
</Node>
<Item id="2"/>
</Node>
I would like the output 1,2,3 (or a similar representation). If this can be done with a single xpath then even better!
I have seen examples of this for lists of sibling elements, but not for a general xml tree structure. I'm also restricted to using xslt 1.0 methods. Thanks!

Selecting all unique items with a single XPath expression (without indexing, beware of performance issues):
//Item[not(#id = preceding::Item/#id)]

Try this (using Muenchian grouping):
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:key name="item-id" match="Item" use="#id" />
<xsl:template match="/Node">
<xsl:for-each select="//Item[count(. | key('item-id', #id)[1]) = 1]">
<xsl:value-of select="#id" />,
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>

Not sure if this is what you mean, but just in case.
In the html
<xsl:apply-templates select="item"/>
The template.
<xsl:template match="id">
<p>
<xsl:value-of select="#id"/> -
<xsl:value-of select="."/>
</p>
</xsl:template>

Related

grouping with complex "selection"

This is the source XML:
<root>
<!-- a and b have the same date entries, c is different -->
<variant name="a">
<booking>
<date from="2017-01-01" to="2017-01-02" />
<date from="2017-01-04" to="2017-01-06" />
</booking>
</variant>
<variant name="b">
<booking>
<date from="2017-01-01" to="2017-01-02" />
<date from="2017-01-04" to="2017-01-06" />
</booking>
</variant>
<variant name="c">
<booking>
<date from="2017-04-06" to="2017-04-07" />
<date from="2017-04-07" to="2017-04-09" />
</booking>
</variant>
</root>
I'd like to group the three variants so that each variants with same #from and #to in each date should be grouped together.
My attempt is:
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output indent="yes"></xsl:output>
<xsl:template match="root">
<variants>
<xsl:for-each-group select="for $i in variant return $i" group-by="booking/date/#from">
<group>
<xsl:attribute name="cgk" select="current-grouping-key()"/>
<xsl:copy-of select="current-group()"></xsl:copy-of>
</group>
</xsl:for-each-group>
</variants>
</xsl:template>
</xsl:stylesheet>
But this gives too many groups. (How) is this possible to achieve?
Using a composite key and XSLT 3.0 you could use
<xsl:template match="root">
<variants>
<xsl:for-each-group select="variant" group-by="booking/date/(#from, #to)" composite="yes">
<group key="{current-grouping-key()}">
<xsl:copy-of select="current-group()"/>
</group>
</xsl:for-each-group>
</variants>
</xsl:template>
which should group any variant elements together which have the same descendant date element sequence.
XSLT 3.0 is supported by Saxon 9.8 (any edition) or 9.7 (PE and EE) or a 2017 release of Altova XMLSpy/Raptor.
Using XSLT 2.0 you could concatenate all those date values with string-join():
<xsl:template match="root">
<variants>
<xsl:for-each-group select="variant" group-by="string-join(booking/date/(#from, #to), '|')">
<group key="{current-grouping-key()}">
<xsl:copy-of select="current-group()"/>
</group>
</xsl:for-each-group>
</variants>
</xsl:template>
Like the XSLT 3.0 solution, it only groups variant with the same sequence of date descendants, I am not sure whether that suffices or whether you might want to sort any date descendants first before computing the grouping key. In the XSLT 3 case you could do that easily with
<xsl:for-each-group select="variant" group-by="sort(booking/date, (), function($d) { xs:date($d/#from), xs:date($d/#to) })!(#from, #to)" composite="yes">
inline (although that leaves 9.8 HE behind as it does not support function expressions/higher order functions, so there you would need to move the sorting to your own user-defined xsl:function and in there use xsl:perform-sort).

msxsl:node-set() not recognized

I am trying to pull nodes out of a node set stored in a variable using the msxsl:node-set() function and am not getting anything. My xml looks like this:
<Root>
<Items olditemnumber="100" newitemnumber="200">
<Item ItemNumber="100" ItemAliasCode="1001" ItemCode="X" />
<Item ItemNumber="100" ItemAliasCode="1002" ItemCode="X" />
<Item ItemNumber="200" ItemAliasCode="2001" ItemCode="X" />
<Item ItemNumber="200" ItemAliasCode="2003" ItemCode="X" />
<Item ItemNumber="100" ItemAliasCode="1003" ItemCode="P" />
<Item ItemNumber="100" ItemAliasCode="1004" ItemCode="P" />
<Item ItemNumber="200" ItemAliasCode="2002" ItemCode="P" />
</Items>
</Root>
In my xslt I try to populate a variable with a subset of the nodes and then call them using the msxsl:node-set() function. This doesn't return anything however.
XSLT looks like this:
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt">
<xsl:template match="//Root">
<xsl:variable name="OldItemNumber" select="/Items/#olditemnumber"/>
<xsl:variable name="NewItemNumber" select="/Items/#newitemnumber"/>
<xsl:variable name="OldItems">
<xsl:value-of select="//Item[#ItemNumber = $OldItemNumber]"/>
</xsl:variable>
<xsl:variable name="NewItems">
<xsl:value-of select="//Item[#ItemNumber = $NewItemNumber]"/>
</xsl:variable>
<xsl:for-each select="msxsl:node-set($OldItems)/Item">
...work
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
The XSLT skips over the for-each loop, though I see in the watch that the the Xpath query grabs the right nodes in assigning the variables. The watch also tells me that the msxsl:node-set() function is undefined. Any help would be appreciated. What am I missing?
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt">
<xsl:template match="//Root">
<xsl:variable name="OldItemNumber" select="/Items/#olditemnumber"/>
<xsl:variable name="NewItemNumber" select="/Items/#newitemnumber"/>
<xsl:variable name="OldItems" select="//Item[#ItemNumber = $OldItemNumber]"/>
<xsl:variable name="NewItems" select="//Item[#ItemNumber = $NewItemNumber]"/>
<xsl:for-each select="$OldItems">
...work
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
msxsl:node-set is for converting a result tree fragment (a.k.a. RTF) to a node set, which is not needed on your case.
xsl:value-of is for creating text nodes, so don't use it for selecting nodes of the input tree that you want to further query/process.

insert PCDATA from the child element into an attribute

I want to insert PCDATA from the child element into a selected node attribute
XML
<root>
<tag>
<tag1>SOME TEXT</tag1>
</tag>
</root>
MY XSL
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xi="http://www.w3.org/2001/XInclude" version="1.0">
<xsl:template match="root">
<tag-out>
<xsl:attribute name="text">
<!-- What should I select? -->
<xsl:value-of select="tag/tag1/???"/>
</xsl:attribute>
<tag-out>
</xsl:template>
...........
</xsl:stylesheet>
Desired output XML
<root-out text="SOME TEXT">
<tag-out/>
</root-out>
Thanks
What's wrong with simply doing
<tag-out text="{tag/tag1}"></tag-out>
? Of course your sample with
<tag-out>
<xsl:attribute name="text">
<xsl:value-of select="tag/tag1"/>
</xsl:attribute>
<tag-out>
is also possible. But as your post is tagged XSLT 2.0 I would at least do
<tag-out>
<xsl:attribute name="text" select="tag/tag1"/>
<tag-out>
if you really need xsl:attribute.

xsl:sort by variable

I've been looking at threads about sorting XML using <xsl:sort> and variables, and still can't get my sorting to work. Here's some XML structure for context:
<records>
<record>
<contributors>
<authors>
<author>Author 1</author>
<author>Author 2</author>
</authors>
</contributors>
<titles>
<title>I'm a Title!</title>
<secondary-title></secondary-title>
</titles>
<dates>
<year>1901</year>
</dates>
</record>
<record>...</record>
<record>...</record>
</records>
And here's the relevant XSL:
<xsl:variable name="sortby"
select="contributors/authors/author[1]" as="element()*"/>
<xsl:for-each select="//record">
<xsl:sort select="$sortby" order="ascending"/>
[a bunch of HTML to render the records as a bibliography]
</xsl:for-each>
If I copy the string in the variable's "select" attributes and paste it into sort, like this:
<xsl:sort select="contributors/authors/author[1]" order="ascending">
then it works. With the variable, it doesn't. I tried it both with and without as="element()*" -- Help?
It is not possible in general to perform dynamic evaluation of XPath expressions -- neither in XSLT/Xpath 1.0 or in XSLT/Xpath 2.0.
This said, one can always implement sorting guided by variables, if there are some limitations on their contents.
Here is an example that solves your specific problem and a class of similar problems:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:param name="pSortName" select="'authors'"/>
<xsl:param name="pSortPosition" select="1"/>
<xsl:template match="node()|#*">
<xsl:copy>
<xsl:apply-templates select="node()|#*"/>
</xsl:copy>
</xsl:template>
<xsl:template match="records">
<records>
<xsl:apply-templates>
<xsl:sort select=
".//*[name()=$pSortName]/*
[position()=$pSortPosition]"/>
</xsl:apply-templates>
</records>
</xsl:template>
</xsl:stylesheet>
when this transformation is applied on this XML document:
<records>
<record>
<contributors>
<authors>
<author>X.Y.Z</author>
<author>A.B.C</author>
</authors>
</contributors>
<titles>
<title>Title B</title>
<secondary-title>Title AB</secondary-title>
</titles>
<dates>
<year>1901</year>
</dates>
</record>
<record>
<contributors>
<authors>
<author>T.U.V</author>
<author>D.E.F</author>
</authors>
</contributors>
<titles>
<title>Title A</title>
<secondary-title>Title BA</secondary-title>
</titles>
<dates>
<year>2001</year>
</dates>
</record>
</records>
the wanted, correct result (the records sorted by first author) is produced:
<records>
<record>
<contributors>
<authors>
<author>T.U.V</author>
<author>D.E.F</author>
</authors>
</contributors>
<titles>
<title>Title A</title>
<secondary-title>Title BA</secondary-title>
</titles>
<dates>
<year>2001</year>
</dates>
</record>
<record>
<contributors>
<authors>
<author>X.Y.Z</author>
<author>A.B.C</author>
</authors>
</contributors>
<titles>
<title>Title B</title>
<secondary-title>Title AB</secondary-title>
</titles>
<dates>
<year>1901</year>
</dates>
</record>
</records>
If we change the parameters to:
<xsl:param name="pSortName" select="'authors'"/>
<xsl:param name="pSortPosition" select="2"/>
then the transformation sorts using as sort-key the second author.
If we change the parameters to:
<xsl:param name="pSortName" select="'titles'"/>
<xsl:param name="pSortPosition" select="1"/>
then the transformation sorts using as sort-key the titles/title element.
If we change the parameters to:
<xsl:param name="pSortName" select="'titles'"/>
<xsl:param name="pSortPosition" select="2"/>
then the transformation sorts using as sort-key the titles/secondary-title element.
Do note: Here we assume that there will be a unique descendent of any element being sorted, whose name is equal to the value specified in pSortName. We also assume that this element has children elements and pSortPosition specifies the position of the child to be used as a sort key.
Two other solutions that haven't been mentioned:
(a) Many processors have an extension, called something like dyn:evaluate() that evaluates an XPath expression supplied in the form of a character string
(b) In some environments it's feasible to modify the stylesheet (using an XSLT transformation of course) before executing it. This allows you to insert whatever XPath expression you need. In XSLT 2.0 you can write the sort key as select="my:sort(.)", and then define my:sort() in a separate xsl:included stylesheet module.
Another related option which I've seen is to use an external entity: select="&sortkey;", where the entity reference can be redirected programmatically to a different XPath expression using an EntityResolver registered with the XML parser.
You can't use a variable in the select= portion of an xsl:sort element. The XSLT specification states:
xsl:sort has a select attribute whose value is an expression. For each node to be processed, the expression is evaluated with that node as the current node and with the complete list of nodes being processed in unsorted order as the current node list.
The expression is evaluated only once, not twice as you seem to expect. Your expression $sortby is evaluated once to result in something that is the same every time (the actual value depends on what was the current node at the time the xsl:variable assignment ran). Therefore, the sort does not change the order of the selected elements.
You must use a specific expression as the sort criteria, as you have discovered.

How can I build a tree from a flat XML list using XSLT?

i use a minimalist MVC framework, where the PHP controler hands the DOM model to the XSLT view (c.f. okapi).
in order to build a navigation tree, i used nested sets in MYSQL. this way, i end up with a model XML that looks as follows:
<tree>
<node>
<name>root</name>
<depth>0</depth>
</node>
<node>
<name>TELEVISIONS</name>
<depth>1</depth>
</node>
<node>
<name>TUBE</name>
<depth>2</depth>
</node>
<node>
<name>LCD</name>
<depth>2</depth>
</node>
<node>
<name>PLASMA</name>
<depth>2</depth>
</node>
<node>
<name>PORTABLE ELECTRONICS</name>
<depth>1</depth>
</node>
<node>
<name>MP3 PLAYERS</name>
<depth>2</depth>
</node>
<node>
<name>FLASH</name>
<depth>3</depth>
</node>
<node>
<name>CD PLAYERS</name>
<depth>2</depth>
</node>
<node>
<name>2 WAY RADIOS</name>
<depth>2</depth>
</node>
</tree>
which represents the following structure:
root
TELEVISIONS
TUBE
LCD
PLASMA
PORTABLE ELECTRONICS
MP3 PLAYERS
FLASH
CD PLAYERS
2 WAY RADIOS
How can I convert this flat XML list to a nested HTML list using XSLT?
PS: this is the example tree from the Managing Hierarchical Data in MySQL.
That form of flat list is very hard to work with in xslt, as you need to find the position of the next grouping, etc. Can you use different xml? For example, with the flat xml:
<?xml version="1.0" encoding="utf-8" ?>
<tree>
<node key="0">root</node>
<node key="1" parent="0">TELEVISIONS</node>
<node key="2" parent="1">TUBE</node>
<node key="3" parent="1">LCD</node>
<node key="4" parent="1">PLASMA</node>
<node key="5" parent="0">PORTABLE ELECTRONICS</node>
<node key="6" parent="5">MP3 PLAYERS</node>
<node key="7" parent="6">FLASH</node>
<node key="8" parent="5">CD PLAYERS</node>
<node key="9" parent="5">2 WAY RADIOS</node>
</tree>
It becomes trivial to do (very efficiently):
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:key name="nodeChildren" match="/tree/node" use="#parent"/>
<xsl:template match="tree">
<ul>
<xsl:apply-templates select="node[not(#parent)]"/>
</ul>
</xsl:template>
<xsl:template match="node">
<li>
<xsl:value-of select="."/>
<ul>
<xsl:apply-templates select="key('nodeChildren',#key)"/>
</ul>
</li>
</xsl:template>
</xsl:stylesheet>
Is that an option?
Of course, if you build the xml as a hierarchy it is even easier ;-p
In XSLT 2.0 it would be rather easy with the new grouping functions.
In XSLT 1.0 it's a little more complicated but this works:
<xsl:template match="/tree">
<xhtml>
<head/>
<body>
<ul>
<xsl:apply-templates select="node[depth='0']"/>
</ul>
</body>
</xhtml>
</xsl:template>
<xsl:template match="node">
<xsl:variable name="thisNodeId" select="generate-id(.)"/>
<xsl:variable name="depth" select="depth"/>
<xsl:variable name="descendants">
<xsl:apply-templates select="following-sibling::node[depth = $depth + 1][preceding-sibling::node[depth = $depth][1]/generate-id() = $thisNodeId]"/>
</xsl:variable>
<li>
<xsl:value-of select="name"/>
</li>
<xsl:if test="$descendants/*">
<ul>
<xsl:copy-of select="$descendants"/>
</ul>
</xsl:if>
</xsl:template>
The heart of the matter is the long and ugly "descendants" variable, which looks for nodes after the current node that have a "depth" child greater than the current depth, but are not after another node that would have the same depth as the current depth (because if they were, they would be children of that node instead of the current one).
BTW there is an error in your example result: "FLASH" should be a child of "MP3 PLAYERS" and not a sibling.
EDIT
In fact (as mentionned in the comments), in "pure" XSLT 1.0 this does not work for two reasons: the path expression uses generate-id() incorrectly, and one cannot use a "result tree fragment" in a path expression.
Here is a correct XSLT 1.0 version of the "node" template (successfully tested with Saxon 6.5) that does not use EXSLT nor XSLT 1.1:
<xsl:template match="node">
<xsl:variable name="thisNodeId" select="generate-id(.)"/>
<xsl:variable name="depth" select="depth"/>
<xsl:variable name="descendants">
<xsl:apply-templates select="following-sibling::node[depth = $depth + 1][generate-id(preceding-sibling::node[depth = $depth][1]) = $thisNodeId]"/>
</xsl:variable>
<xsl:variable name="descendantsNb">
<xsl:value-of select="count(following-sibling::node[depth = $depth + 1][generate-id(preceding-sibling::node[depth = $depth][1]) = $thisNodeId])"/>
</xsl:variable>
<li>
<xsl:value-of select="name"/>
</li>
<xsl:if test="$descendantsNb > 0">
<ul>
<xsl:copy-of select="$descendants"/>
</ul>
</xsl:if>
</xsl:template>
Of course, one should factor the path expression that is repeated, but without the ability to turn "result tree fragments" into XML that can actually be processed, I don't know if it's possible? (writing a custom function would do the trick of course, but then it's much simpler to use EXSLT)
Bottom line: use XSLT 1.1 or EXSLT if you can!
2nd Edit
In order to avoid to repeat the path expression, you can also forget the test altogether, which will simply result in some empty that you can either leave in the result or post-process to eliminate.
very helpful!
one suggestion is moving the < ul > inside the template would remove the empty ul.
<xsl:template match="tree">
<xsl:apply-templates select="node[not(#parent)]"/>
</xsl:template>
<xsl:template match="node">
<ul>
<li>
<xsl:value-of select="."/>
<xsl:apply-templates select="key('nodeChildren',#key)"/>
</li>
</ul>
</xsl:template>
</xsl:stylesheet>
You haven't actually said what you'd like the html output to look like, but I can tell you that from an XSLT point of view going from a flat structure to a tree is going to be complex and expensive if you're also basing this on the position of items in the tree and their relation to siblings.
It would be far better to supply a <parent> attribute/node than the <depth>.