I have an XML with 2 XML fragments, 1st one is a fragment where the new values must be applied (which can have pretty complex elements) like
... some static parents
<a:element1>
<a:subelement tag="someString">
<a:s1>a</a:s1>
</a:subelement>
</a:element1>
<a:element2>b</a:element2>
<a:element3>c</a:element3>
... lots of other elements like the above ones
and 2nd fragment that has XPaths generated from the first XML and a new value, like
<field>
<xpath>/Parent/element1/subelement[#tag="someString"]/s1</xpath>
<newValue>1</newValue>
</field>
<field>
<xpath>/Parent/element2</xpath>
<newValue>2</newValue>
</field>
We might not have new values to apply for all the elements in the first fragment.
I'm struggling to make an XSLT transformation that should apply the new values to the places indicated by the XPaths.
The output should be:
... some static parents
<a:element1>
<a:subelement tag="someString">
<a:s1>1</a:s1>
</a:subelement>
</a:element1>
<a:element2>2</a:element2>
... lots of other elements like the above ones
I have access to xalan:evaluate to evaluate the dynamic xpath. I'm trying different solutions, I will write them here when they will start to make sense.
Any ideas of approaches are well received. Thanks
Oki, I found out how, and I will write the answer here maybe someone sometime will need this:
<xsl:template match="/">
<!-- static parents -->
<a:Root>
<xsl:apply-templates select="/a:Root/a:Parent" />
</a:Root>
</xsl:template>
<xsl:template match="#*|*|text()">
<xsl:variable name="x" select="generate-id(../.)" />
<xsl:variable name="y" select="//field[generate-id(xalan:evaluate(xpath)) = $x]" />
<xsl:choose>
<xsl:when test="$y">
<xsl:value-of select="$y/newValue" />
</xsl:when>
<xsl:otherwise>
<xsl:copy>
<xsl:apply-templates select="#*|*|text()" />
</xsl:copy>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
And to explain the transformation:
I'm writing down part that is static and then call apply-templates on the fragment I'm interested in, that has a liquid structure.
Then I'm using a slightly modified identity transformation that copies everything from source to target (starting from the /a:Root/a:Parent fragment), except when we position ourselves on the text I'm interested in changing.
The text() I'm interested in will have as parent (../.) the element referred by an xpath string found in the second fragment. Variable x means, in the context of the when, this element.
Variable y finds a field element that has as child an xpath element that if evaluated using xalan will refer to the same element that the x variable relates to.
Now I used generate-id() in order to compare the physical elements, otherwise it would have compared by the toString of the element (which is wrong). If variable y doesn't exist, it means that I have no xpath element for this element that could have changed, and I'm leaving it alone. If the y variable exists, I can get from it the newValue and I'm currently positioned on the element which text I want to update.
Related
Assume my xml input is a MFMATR element with a few child elements, such as: TRLIST, INTRO, and SBLIST -- in that document order. I am converting to HTML.
I have a template that matches on the MFMATR element, and wants to run xsl:apply-templates on the 3 child elements, but I want INTRO to be processed first (listed first in the HTML). The other two (TRLIST and SBLIST) should keep their relative document order, as long as INTRO comes before both of them.
So I'd like to run <xsl:apply-templates select="INTRO, *"> but not have INTRO matched twice. (Using this syntax with xsl 3.0 causes dupes for me.) I also don't want to explicitly list every tag in the select expression, so unknown tags will still be processed.
A 2nd real life example is this: <xsl:apply-templates select="TITLE, CHGDESC, *"/>. Again, right now that is causing dupes I don't want.
I am using Saxon.
So I'd like to run <xsl:apply-templates select="INTRO, *"> but not have INTRO matched twice
Try:
<xsl:apply-templates select="INTRO, * except INTRO">
This seems to work. If someone has a better answer, let me know and I will change it.
There is no DRY violation here -- no repeated element names or variable names. I want it to look clean at all the call sites I will have.
It seems idiomatic to me since the function was pulled from w3's own website!
<xsl:template match="MFMATR">
<!-- Process INTRO first, no matter where it appears -->
<xsl:variable name="nodes" select="INTRO, *"/>
<xsl:apply-templates select="kp:distinct_nodes_stable($nodes)"/>
</xsl:template>
<xsl:template match="INTRO">
<xsl:variable name="nodes" select="TITLE, CHGDESC, *"/>
<xsl:apply-templates select="kp:distinct_nodes_stable($nodes)"/>
</xsl:template>
<!-- Discard duplicate elements in $seq, but keep their ordering -->
<!-- Adapted from https://www.w3.org/TR/xpath-functions/#func-distinct-nodes-stable -->
<xsl:function name="kp:distinct_nodes_stable" as="node()*">
<xsl:param name="seq" as="node()*"/>
<xsl:sequence select="fold-left($seq, (),
function($foundSoFar as node()*, $this as node()) as node()* {
if ($foundSoFar intersect $this)
then $foundSoFar
else ($foundSoFar, $this)
}) "/>
</xsl:function>
If I have an XSL that creates output like this simple/rough example:
<Parent1>
<ABC><xsl:value-of select="SomeValue1"/></ABC>
<DEF><xsl:value-of select="SomeValue2"/></DEF>
<GHI><xsl:value-of select="SomeValue3"/></GHI>
...
<YZ><xsl:value-of select="SomeValue9"/></YZ>
</Parent1>
... within this same XSL, how can I count how many children the XSL will produce?
You can generate your content into a variable, count the children in the variable, and then emit the content of the variable:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:template match="/">
<xsl:variable name="temp-results">
<Parent1>
<ABC><xsl:value-of select="SomeValue1"/></ABC>
<DEF><xsl:value-of select="SomeValue2"/></DEF>
<GHI><xsl:value-of select="SomeValue3"/></GHI>
...
<YZ><xsl:value-of select="SomeValue9"/></YZ>
</Parent1>
</xsl:variable>
<xsl:text>Number of children:</xsl:text>
<xsl:value-of select="count($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="$output" />
</xsl:template>
Its output is
Outputting 5 elements.
<ABC>
<ZZZ>Some Grandchild</ZZZ>
</ABC>
<DEF/>
<GHI/>
...
<YZ/>
This code accomplishes three things:
First it generates the result and puts it into the variable
It counts all the
children (child::* axis) or
descendants (descendant::* axis) as in the example above
of the elements in the variable
It copies the variable to the output stream
This approach can even be nested - meaning that it can be applied several times, one after another.
Your choices are:
(a) find a way of computing the result as a function of the input
(b) capture the output in a variable and run a second phase of processing against that variable.
(c) a blend of the above: compute some intermediate result in a variable, and use that variable as input to both processes.
In the example you've given, the first approach works perfectly well; but I guess your real problem is more complex than that, otherwise you wouldn't be asking.
xsl
<xsl:variable name="varName>
<xsl:value-of select="/can/be/a/long/path/down/xml/item[#id=1] />
</xsl:variable>
xml
<xml>
<item id="1" text="Yes">
<item id="2" text="No">
</xml>
use
I was thinking I could use like this:
<xsl:when test="$varName/#text = 'Yes'">
blah
</xsl:when>
but blank space is generated in place of variable. Is this even possible, have a node as a variable and use elsewhere?
<xsl:variable name="varName">
<xsl:value-of select="/can/be/a/long/path/down/xml/item[#id=1]" />
</xsl:variable>
This is one of the most common XSLT errors I see. Usually what people intended is:
<xsl:variable name="varName" select="/can/be/a/long/path/down/xml/item[#id=1]"/>
And most of the time, the code works just fine, except that it's a lot slower than it needs to be. But sometimes the fact that the two constructs are quite different beneath the covers comes back to bite you.
To understand the difference, xsl:variable with a select attribute binds the variable to whatever the select expression evaluates to, which in this case is a set of zero or more item elements. By contrast, xsl:variable with nested instructions creates a document node (XSLT 2.0) or result tree fragment (XSLT 1.0) whose content is a COPY of whatever those instructions produce. In this case, because the content is an xsl:value-of instruction, the variable contains a copy of the string-value of the selected node.
And of course, the string value of the selected node doesn't have any attributes, so test="$varname/#text = 'x'" will always return false.
XSLT2.0 seems to allow declaring key inline, inside the <key> element.
All the examples I have seen declare an intermediate XML fragment and match on that, using #use. I think that is wasteful.
Can you please provide an example of a XSLT 2.0 key declaration using sequence constructor inside the key element rather than #use?
Usually the value that you want to index is a very simple function of the objects being indexed, so the #use attribute works perfectly well. You can use a contained sequence constructor for more complex cases if you need to, but I've very rarely seen it needed. For example you might want to index sections by their section number like this:
<xsl:key name="k" match="section">
<xsl:number level="multi" count="section" format="1.1.1"/>
</xsl:key>
I don't know what makes you think that using the #use attribute is "wasteful".
I don't think I have used that feature so far and I can't think of a good sample for an obvious use case but let's assume foo elements have some value child elements and we want to sort the value elements and only key on the first or last few in sort order so we could use e.g.
<xsl:key name="by-first-three-values" match="foo">
<xsl:for-each select="value/xs:decimal(.)">
<xsl:sort select="."/>
<xsl:if test="position() lt 4">
<xsl:sequence select="."/>
</xsl:if>
</xsl:for-each>
</xsl:key>
Of course you could avoid that use by writing a function that sorts with perform-sort and then call that function in use="mf:sort(value)[position() lt 4]" but I guess there is at least the flexibility to do it inline of the xsl:key.
What I am after is even more simple, something similar to:
<xsl:key name="AcronymKey" match="a:acronymItem" use="a:acronym"/>
<xsl:template name="AcronymnStandsFor">
<xsl:param name="acronym"/>
<!-- change context to current document so the key will work -->
<xsl:for-each select="document('')">
<xsl:value-of select="key('AcronymKey',$acronym)/a:standsFor"/>
</xsl:for-each>
</xsl:template>
<a:acronymList>
<a:acronymItem>
<a:acronym>Ant</a:acronym>
<a:standsFor>Another Neat Tool</a:standsFor>
</a:acronymItem>
</a:acronymList>
But where the actual key is inside the key element. Is that possible, given the syntax?
I've got an xsl:variable that contains a pre-processed set (DoesNotContainChildElement). I think msxsl:node-set() is adding a root element so position is always 1. But what I need it the top 15 elements.
<xsl:variable name="Summary">
<xsl:for-each select="msxsl:node-set($DoesNotContainChildElement)">
<xsl:if test="position() < 16">
<xsl:copy-of select="."></xsl:copy-of>
</xsl:if>
</xsl:for-each>
No, the function msxsl:node-set does not add any root node, it is simply that with XSLT 1.0 a sample like
<xsl:variable name="rtf1">
<item>1</item>
<item>2</item>
<item>3</item>
</xsl:variable>
creates a result tree fragment and "A result tree fragment is treated equivalently to a node-set that contains just a single root node". So in the sample above we have a result tree fragment with a single root node containing three item child elements.
Applying the msxsl:node-set(rtf1) extension function then gives you a node-set instead of a result tree fragment where now the node-set contains a single root node with three item child elements. Thus if you want to access the item elements you need msxsl:node-set($rtf1)/* or more general msxsl:node-set($rtf1)/node() to access all child nodes.
You may try msxsl:node-set($DoesNotContainChildElement)/*. If it's true that msxsl:node-set() adds a root node, then adding /* to your path will iterate over the children, where you can test for position.
Alternatively you could simply use <xsl:apply-templates select="msxsl:node-set($DoesNotContainChildElement)/*" mode="testposition"/> and <xsl:template match="*" mode="testposition">….
There's only one variable $DoesNotContainChildElement so a for-each will only yield value 1 for position().
You can check that by running the following:
<xsl:for-each select="$x">
<pos1><xsl:value-of select="position()"/></pos1>
</xsl:for-each>
<xsl:for-each select="$x/*">
<pos2><xsl:value-of select="position()"/></pos2>
</xsl:for-each>
Where x is a (node-set type) variable.
The result will look something like
<pos1>1</pos1>
<pos2>1</pos2>
<pos2>2</pos2>
<pos2>3</pos2>
<pos2>...</pos2>
Adding <xsl:copy-of select="."/> will result in the output of the entire variable contents in case of the first for-each above, whereas for the second for-each it will result in the output of each sub-element of the variable one-by-one.
The second form is the one to use if you wish to output only selected sub-elements.
The same holds when you first apply the node-set function to change an rtf into a node-set.