My understanding has been that, despite the fact that XSLT's "node-sets" are called "sets", they are, in fact, ordered lists of nodes (which is why each node is associated with an index). I've therefore been trying to use the "|" operator to concatenate node-sets such that the order of the nodes is respected.
What I am attempting to accomplish is something like the following JavaScript code:
[o1,o2,o3].concat([o4,o5,o6])
Which yields:
[o1,o2,o3,o4,o5,o6]
But, consider the following reduced example:
testFlatten.xsl
<?xml version="1.0"?>
<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
<xsl:output method="xml"/>
<xsl:template match="/">
<xsl:variable name="parentTransition" select="//*[#id='parentTransition']"/>
<xsl:variable name="childTransition" select="//*[#id='childTransition']"/>
<xsl:variable name="parentThenChildTransitions" select="$parentTransition | $childTransition"/>
<xsl:variable name="childThenParentTransitions" select="$childTransition | $parentTransition"/>
<return>
<parentThenChildTransitions>
<xsl:copy-of select="$parentThenChildTransitions"/>
</parentThenChildTransitions>
<childThenParentTransitions>
<xsl:copy-of select="$childThenParentTransitions"/>
</childThenParentTransitions>
</return>
</xsl:template>
</xsl:stylesheet>
Given the following input:
<?xml version="1.0"?>
<root>
<element id="parentTransition"/>
<element id="childTransition"/>
</root>
Which yields (with xsltproc):
<?xml version="1.0"?>
<return>
<parentThenChildTransitions>
<element id="parentTransition"/><element id="childTransition"/>
</parentThenChildTransitions>
<childThenParentTransitions>
<element id="parentTransition"/><element id="childTransition"/>
</childThenParentTransitions>
</return>
So the "|" operator in fact does not respect the order of the node-set operands. Is there a way I can concatenate node-sets such that order is respected?
This is actually not an XSLT but an XPath question.
In XPath 1.0 there isn't anything similar to a "list" datatype. A node-set is a set and it has no order.
In XPath 2.0 there is the sequence data type. Any items in a sequence are ordered. This has nothing to do with document order. Also, the same item (or node) can appear more than once in a sequence.
So, in XSLT 2.0 one just uses the XPath 2.0 sequence concatenation operator ,:
//*[#id='parentTransition'] , //*[#id='childTransition']
and this evaluates to the sequence of all elements in the document with id attribute 'parentTransition' followed by all elements in the document with id attribute 'childTransition'
In XSLT it is still possible to access and process nodes not in document order: for example using the <xsl:sort> instruction -- however the set of nodes that are processed as result of <xsl:apply-templates> or <xsl:for-each> is a node-list -- not a node-set.
Another example of evaluating nodes not in document order is the position() function within <xsl:apply-templates> or <xsl:for-each> that have a <xsl:sort> child or within a predicate of a location step (of an XPath expression) in which a reverse axis is used (such as ancesstor:: or preceeding::)
In XSLT 1.0, you can process nodes in a selected order (for example by use of xsl:sort), but you can't hold a list of nodes in a variable. The only thing you can hold in a variable (or pass to a template, etc) is a node-set; node-sets have no intrinsic order, but when you process them, they are always processed in document order unless you use xsl:sort to request a different processing order.
You might be able to solve your problem by copying the nodes:
<xsl:variable name="temp">
<xsl:copy-of select="$ns0"/>
<xsl:copy-of select="$ns1"/>
</xsl:variable>
...
<xsl:apply-templates select="exslt:node-set($temp/*)"/>
but this depends on your use-case.
Switch to XSLT 2.0 if you can!
The "|" operator will retain nodes in document order. In XSLT 1.0 you will need to have sequential copy or for-each operations.
<xsl:copy-of select="$parentTransition"/>
<xsl:copy-of select="$childTransition"/>
Related
If I have an XSL that creates output like this simple/rough example:
<Parent1>
<ABC><xsl:value-of select="SomeValue1"/></ABC>
<DEF><xsl:value-of select="SomeValue2"/></DEF>
<GHI><xsl:value-of select="SomeValue3"/></GHI>
...
<YZ><xsl:value-of select="SomeValue9"/></YZ>
</Parent1>
... within this same XSL, how can I count how many children the XSL will produce?
You can generate your content into a variable, count the children in the variable, and then emit the content of the variable:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:template match="/">
<xsl:variable name="temp-results">
<Parent1>
<ABC><xsl:value-of select="SomeValue1"/></ABC>
<DEF><xsl:value-of select="SomeValue2"/></DEF>
<GHI><xsl:value-of select="SomeValue3"/></GHI>
...
<YZ><xsl:value-of select="SomeValue9"/></YZ>
</Parent1>
</xsl:variable>
<xsl:text>Number of children:</xsl:text>
<xsl:value-of select="count($temp-results/Parent1/*)"/>
<xsl:sequence select="$temp-results"/>
</xsl:template>
</xsl:stylesheet>
One possibility is wrapping the whole output process in a variable and then count its descendants.
So, for example, you can use the following XSLT code
<xsl:template match="/Parent1">
<xsl:variable name="output">
<ABC><xsl:value-of select="SomeValue1"/><ZZZ>Some Grandchild</ZZZ></ABC>
<DEF><xsl:value-of select="SomeValue2"/></DEF>
<GHI><xsl:value-of select="SomeValue3"/></GHI>
...
<YZ><xsl:value-of select="SomeValue9"/></YZ>
</xsl:variable>
<xsl:value-of select="concat('Outputting ', count($output/descendant::*), ' elements.
')" />
<xsl:copy-of select="$output" />
</xsl:template>
Its output is
Outputting 5 elements.
<ABC>
<ZZZ>Some Grandchild</ZZZ>
</ABC>
<DEF/>
<GHI/>
...
<YZ/>
This code accomplishes three things:
First it generates the result and puts it into the variable
It counts all the
children (child::* axis) or
descendants (descendant::* axis) as in the example above
of the elements in the variable
It copies the variable to the output stream
This approach can even be nested - meaning that it can be applied several times, one after another.
Your choices are:
(a) find a way of computing the result as a function of the input
(b) capture the output in a variable and run a second phase of processing against that variable.
(c) a blend of the above: compute some intermediate result in a variable, and use that variable as input to both processes.
In the example you've given, the first approach works perfectly well; but I guess your real problem is more complex than that, otherwise you wouldn't be asking.
I wish to construct an XSL node set variable using a contained for-each loop. It is important that the constructed node set is the original (a selected) node set, not a copy.
Here is a much simplified version of my problem (which could of course be solved with a select, but that's not the point of the question). I've used the <name> node to test that the constructed node set variable is in fact in the original tree and not a copy.
XSL version 1.0, processor is msxsl.
Non-working XSL:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" encoding="iso-8859-1" omit-xml-declaration="yes" />
<xsl:template match="/">
<xsl:variable name="entries">
<xsl:for-each select="//entry">
<xsl:copy-of select="."/>
</xsl:for-each>
</xsl:variable>
<xsl:variable name="entryNodes" select="msxsl:node-set($entries)"/>
<xsl:for-each select="$entryNodes">
<xsl:value-of select="/root/name"/>
<xsl:value-of select="."/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
XML input:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<name>X</name>
<entry>1</entry>
<entry>2</entry>
</root>
Wanted output:
X1X2
Actual output:
12
Of course the (or a) problem is the copy-of, but I can't work out a way around this.
There isn't a "way around it" in XSLT 1.0 - it's exactly how this is supposed to work. When you have a variable that is declared with content rather than with a select then that content is a result tree fragment consisting of newly-created nodes (even if those nodes are a copy of nodes from the original tree). If you want to refer to the original nodes attached to the original tree then you must declare the variable using select. A better question would be to detail the actual problem and ask how you could write a suitable select expression to find the nodes you want without needing to use for-each - most uses of xsl:if or xsl:choose can be replaced with suitably constructed predicates, maybe involving judicious use of xsl:key, etc.
In XSLT 2.0 it's much more flexible. There's no distinction between node sets and result tree fragments, and the content of an xsl:variable is treated as a generic "sequence constructor" which can give you new nodes if you construct or copy them:
<xsl:variable name="example" as="node()*">
<xsl:copy-of select="//entry" />
</xsl:variable>
or the original nodes if you use xsl:sequence:
<xsl:variable name="example" as="node()*">
<xsl:sequence select="//entry" />
</xsl:variable>
I wish to construct an XSL node set variable using a contained
for-each loop.
I have no idea what that means.
It is important that the constructed node set is the original (a
selected) node set, not a copy.
This part I think I understand a little better. It seems you need to replace:
<xsl:variable name="entries">
<xsl:for-each select="//entry">
<xsl:copy-of select="."/>
</xsl:for-each>
</xsl:variable>
with:
<xsl:variable name="entries" select="//entry"/>
or, preferably:
<xsl:variable name="entries" select="root/entry"/>
The resulting variable is a node-set of the original entry nodes, so you can do simply:
<xsl:for-each select="$entries">
<xsl:value-of select="/root/name"/>
<xsl:value-of select="."/>
</xsl:for-each>
to get your expected result.
Of course, you could do the same thing by operating directly on the original nodes, in their original context - without requiring the variable.
In response to the comments you've made:
We obviously need a better example here, but I think I am getting a vague idea of where you want to go with this. But there are a few things you must understand first:
1.
In order to construct a variable which contains a node-set of nodes in their original context, you must use select. This does not place any limits whatsoever on what you can select. You can do your selection all at once, or in stages, or even in a loop (here I mean a real loop). You can combine the intermediate selections you have made in any way sets can be combined: union, intersection, or difference. But you must use select in all these steps, otherwise you will end up with a set of new nodes, no longer having the context they did in the source tree.
IOW, the only difference between using copy and select is that the former creates new nodes, which is precisely what you wish to avoid.
2.
xsl:for-each is not a loop. It has no hierarchy or chronology. All the nodes are processed in parallel, and there is no way to use the result of previous iteration in the current one - because no iteration is "previous" to another.
If you try to use xsl:for-each in order to add each of n processed nodes to a pre-existing node-set, you will end up with n results, each containing the pre-existing node-set joined with one of the processed nodes.
3.
I think you'll find the XPath language is quite powerful, and allows you to select the nodes you want without having to go through the complicated loops you hint at.
It might help if you showed us a problem that can't be trivially solved in XSLT 1.0. You can't solve your problem the way you are asking for: there is no equivalent of xsl:sequence in XSLT 1.0. But the problem you have shown us can be solved without such a construct. So please explain why you need what you are asking for.
I have a fairly convoluted XML file and I need to do a weighted average of a few values within it using XSL. I am able to complete a sum of the weights OR of the values, but I cannot get the multiplication to work. I get an error:
XPTY0004: A sequence of more than one item is not allowed as the first
operand of '*'
I am not able to share the XML, but I have simplified the XML to the following example (assume there are a large number of foos):
<group>
<fooList>
<foo>
<attributeList>
<Attribute ID="1" Weight="0.5">
<otherParams />
</Attribute>
</attributeList>
<Properties>
<PhysicalProperties>
<Volume Average="125" Unknown="50" />
</PhysicalProperties>
</Properties>
</foo>
</fooList>
</group>
My current attempt to get the weighted average is the following:
<xsl:variable name="WeightedVolume" select="sum(/group/fooList/foo[attributeList/Attribute/[#ID=$test_id]]/attributeList/Attribute/#Weight * /group/fooList/foo[attributeList/Attribute/[#ID=$test_id]]/Properties/PhysicalProperties/Volume/#Average)"/>
I know there are similar questions available - but most of them deal with something like summing and multiplying foo
<foo>
<Weight>0.5</Weight>
<VolumeAverage>125</VolumeAverage>
</foo>
The answer on this StackOverflow Question appeals to me, but I cannot seem to make it work.
I'm using Saxon-HE 9.5.1.1N from Saxonica, with Visual Studio 2013.
Edited
I was able to get something to work for XSL 2, but need to have a fall-back for XSL1.
<xsl:variable name="WeightedVolume" select="sum(for $i in /group/FooList/foo[attributeList/Attribute[#ID=$test_id] return $i/AttributeList/Attribute/#Weight * $i/Properties/PhysicalProperties/Volume/#Average)"/>
To follow the example in that question you linked to, you would use this in XSLT 2.0/XPath 2.0:
<xsl:variable name="FoosToCalculate"
select="/group/fooList/foo[attributeList/Attribute/#ID = $test_id]" />
<xsl:variable name="WeightedVolume"
select="sum($FoosToCalculate/(attributeList/Attribute/#Weight *
Properties/PhysicalProperties/Volume/#Average)
)"/>
Doing this summing in XSLT 1.0 is considerably more involved and typically involves either using recursive templates or some manifestation of the node-set() function. Here is an example of the latter:
<xsl:stylesheet version="1.0"
xmlns:ex="http://exslt.org/common"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text"/>
<xsl:template match="/">
<!-- determine $test_id however you need to -->
<xsl:variable name="products">
<xsl:for-each
select="/group/fooList/foo[attributeList/Attribute/#ID = $test_id]">
<product>
<xsl:value-of select="attributeList/Attribute/#Weight *
Properties/PhysicalProperties/Volume/#Average" />
</product>
</xsl:for-each>
</xsl:variable>
<xsl:value-of select="sum(ex:node-set($products)/product)"/>
</xsl:template>
</xsl:stylesheet>
For completeness, if you want to sum over a computed quantity in XSLT 1.0, there are three ways of doing it:
(a) recursion: write a recursive template that processes the items in the sequence one by one, computing the total as it goes.
(b) create an XML tree in which the computed quantities are node values, and then process this tree using the sum() function. To do this in a single stylesheet you will need the exslt:node-set() extension function.
(c) use an extension function provided by the XSLT vendor, or user-written using the facilities provided by the vendor for calling external functions.
In XSLT 2.0, it can always be done using the construct
sum(for $x in node-set return f($x))
where f is a function that computes the quantity.
I am a novice XSLT developer. I have been asked to fix an issue on a project where the original developer is no longer with us. In the XSLT, there is a for-each loop using a key and a count
<xsl:for-each select="ns0:BOM[count(. | key('subsat', ns0:BomText01)[1]) = 1][ns0:BomText01]">
...
This is the key:
<xsl:key name="subsat" match="ns0:Parts/ns0:BOM[ns0:FindNum!='0']" use="ns0:BomText01" />
In the XML file being transformed, there are two sibling nodes that represent sub-parts:
<ns0:BOM referentId="10000:65091335:65359080">
<ns0:BomText01>3069260-303-SUB0027</ns0:BomText01>
<ns0:ItemNumber>My_part_1</ns0:ItemNumber>
<ns0:ItemType>Part</ns0:ItemType>
<ns0:Qty>67</ns0:Qty>
</ns0:BOM>
<ns0:BOM referentId="10000:65102551:86713230">
<ns0:BomText01>3069260-303-SUB0027</ns0:BomText01>
<ns0:ItemNumber>My_part_2</ns0:ItemNumber>
<ns0:ItemType>Part</ns0:ItemType>
<ns0:Qty>67</ns0:Qty>
</ns0:BOM>
However, the loop is only picking up the first node (My_part_1). I suspect it's because of the count=1 but I really don't know. And I don't know how to modify it. Ideas? If I need to include more data, let me know.
Assuming that the relevant part of your XSLT looks something like this:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ns0="ns0" version="1.0">
<xsl:key name="subsat" match="ns0:BOM[ns0:FindNum!='0']" use="ns0:BomText01"/>
<xsl:template match="ns0:Parts">
<xsl:for-each
select="ns0:BOM[count(. | key('subsat', ns0:BomText01)[1]) = 1][ns0:BomText01]">
<xsl:value-of select="."/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
It will only print the first of the elements because it is selecting the BOM elements which have an unique BomText01 value. That's the expected result.
If the BomText01 is an ID field (as it seems it is) and you expected to get both result (perhaps, because their ItemNumber contains different values), the error is possibly in your source (which assigned equal IDs when it should not have done so).
If you change one of those values in the source, you should be able to select both and verify this.
I'm trying to count the elements my transformation generates (must use XLST1). For example, my transformation creates:
<Parent>
<ElementX Att1="2"/>
<ElementY Att1="1"/>
<ElementZ Att1="6"/>
</Parent>
I need to print 3 within the same transformation, because there are 3 child elements.
Can this be done?
Thanks.
It would help a lot if you provide some extract of your XSLT.
I cn't give you a XSLT code without it. I'll try to give some "way" to the answer :
One solution could be to store the output into a nodeset (use the XSLT 1.0 extension which provides the nodeset() function) and apply the XPath count() function on this variable. After that just output your variable with xsl:value-of, and your count result the same way.
Here is a demo how to do this:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ext="http://exslt.org/common" exclude-result-prefixes="ext">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:template match="/">
<xsl:variable name="vrtfPass1">
<xsl:apply-templates/>
</xsl:variable>
<xsl:value-of select="count(ext:node-set($vrtfPass1)/*/*)"/>
</xsl:template>
<xsl:template match="/*">
<Parent>
<ElementX Att1="2"/>
<ElementY Att1="1"/>
<ElementZ Att1="6"/>
</Parent>
</xsl:template>
</xsl:stylesheet>
When this transformation is applied on any XML document (not used in this Demo), the wanted, correct result is produced:
3
Explanation:
A general way to process the result of the transformation (in a single transformation), is to organize it in two passes where we save the result of the first pass in a variable.
In the second pass we access the result and do the additional processing.
Do note that in XSLT 1.0 if the variable that captures the result of the first pass is of the infamous RTF (Result Tree Fragment) type and needs to be converted to a regular tree in order of any nodes inside this tree to be accessible (xsl:copy-of and string() are still allowed on an RTF).
This conversion to a regular tree is done by an extension function, which most often has the name node-set and always belongs to a vendor-defined namespace. In this demo we are using the node-set() extension function that belongs to the EXSLT namespace -- because most XSLT 1.0 processors implement EXSLT.
For more information on multi-pass processing, see this: Two phase processing: Do not output empty tags from phase-1 XSLT 2.0 processing