XSLT: How to check equality of children

Question

I have an array of XML <row> elements each of which can then have an array of <query> elements. It looks something like this:

<row><query></query><query></query></row>
<row><query></query><query></query></row>
<row><query></query><query></query></row>
<row><query></query><query></query></row>

I want to print a table in case the query children are different across the row elements and a comma separated string if the query children are same across all the row children.

I am composing an <xsl:when> for this:

<xsl:choose>
  <xsl:when test="[Table condition]">
    <!--code to print table-->
  </xsl:when>
  <xsl:otherwise>
    <!--code to print string-->
  </xsl:otherwise>
</xsl:choose>

What should be the Table Condition?

I am using XSLT v 1.0. I know there is something called deep equals but don't understand how to use it here.

Can you help me here?

Sorry, don't understand what you need... Please provide sample data (within your empty XML structure) and the expected output. — Shnugo, Nov 17 '15 at 08:28
Do you simply want to compare the number of child elements? Or their data as well? — Martin Honnen, Nov 17 '15 at 08:40
@MartinHonnen I want to compare their data as well. The number of children are assumed to be always equal in all `row`s but the data may differ. — Core_Dumped, Nov 17 '15 at 09:32
@Core_Dumped See: http://stackoverflow.com/questions/33610324/xslt-how-to-find-the-count-of-unique-children-of-a-node/33614575#33614575 — michael.hor257k, Nov 17 '15 at 11:43

score 1 · Answer 1 · answered Nov 17 '15 at 10:09

1

deep-equal is a function introduced in XSLT/XPath 2.0, here is a sample using that (which then of course requires using an XSLT 2.0 processor like Saxon 9, Altova, XmlPrime):

<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>

    <xsl:template match="table[not(row[some $sibling in ../row satisfies not(deep-equal(., $sibling))])]">
        <xsl:value-of select="row/query" separator=","/>
    </xsl:template>
</xsl:transform>

I have obviously put the condition for one case in a match pattern and simply let the copying of other tables work through the identity transformation.

With a sample input like

<root>
    <table>
        <row><query>1</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
    </table>
    <table>
        <row><query>2</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
    </table>
</root>

the result is

<root>
    1,2,1,2,1,2,1,2
    <table>
        <row><query>2</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
        <row><query>1</query><query>2</query></row>
    </table>
</root>

answered Nov 17 '15 at 10:09

Martin Honnen

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Is there a way to do this in XSLT 1.0? I am using that. – Core_Dumped Nov 17 '15 at 10:12
Do you know the number of `query` elements when writing the XSLT code? – Martin Honnen Nov 17 '15 at 10:20
No, I do not. They may vary but the number of them is same for all the `row` elements – Core_Dumped Nov 17 '15 at 13:56
It is difficult with XSLT 1.0 to achieve the comparison if there can be an unknown number of `query` elements which additionally have complex contents. Maybe Dimitre Novatchev comes along later and feels challenged and is going to help you. I am more inclined to suggest to move to XSLT 2.0 in such cases where a lot of code is needed in XSLT 1.0 – Martin Honnen Nov 17 '15 at 14:04
I tried to change my stylesheet version to 2.0 (as suggested in http://stackoverflow.com/questions/9387396/upgrading-xslt-1-0-to-xslt-2-0) but I don't seem to use the XSLT 2.0 functionalities. Do I have to install a new XSL processor as well? If so, how? – Core_Dumped Nov 17 '15 at 14:15
Well options are Saxon 9, Altova (I am not sure they provide the processor as a standalone, you might need to install a trial version of their XML IDE XMLSpy) or XmlPrime. The open source version of Saxon 9, Saxon 9 HE comes in a Java and in a .NET version, see http://saxonica.com/welcome/welcome.xml for details about download, installation, documentation. – Martin Honnen Nov 17 '15 at 14:19
Yes, changing the version number in your stylesheet doesn't automagically convert your XSLT processor into a 2.0 processor. – Michael Kay Nov 17 '15 at 15:32

score 0 · Answer 2 · answered Nov 17 '15 at 10:12

If there is only text inside your query elements, it shouldn't be too difficult in XSLT 1.0. For instance, I assume a sample of two rows might look like this:

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <row><query>foo</query><query>foo</query></row>
    <row><query>foo1</query><query>foo2</query></row>
</root>

If you process this data by an XSLT template like

<xsl:for-each select="//row">
        <xsl:choose>
            <xsl:when test="query[not(. = preceding-sibling::query or . = following-sibling::query)]">
                There is at least one query element which is different from the others
                in the same raw.
            </xsl:when>
            <xsl:otherwise>
                All query elements in this row are equal.
            </xsl:otherwise>
        </xsl:choose>
      </xsl:for-each>

you get the expected result: The first row is treated as "equal", the other as "different". This is done by checking if the preceding and following query: Is there at least one which is not both equal to all preceding and following siblings?

Is this more or less what you're looking for?

That is a dangerous comparison, no? If you have `abc` and `abc` then your comparison will give true although the values are different. — Martin Honnen, Nov 17 '15 at 10:19
There is not necessarily text inside `query`. It might have one or more children. We can assume that the children across `row`s for the same position of `query` have the same tags but might not have the same value and that is what I am trying to compare. — Core_Dumped, Nov 17 '15 at 10:20
@Martin Honnen, at least with Saxon 6 it returns "false" in both cases (as it should) @Core_Dumped: Well, in this case, my suggested solution won't work. A workaround could be to transform all content of `query` to a string and compare it afterwards. — cis, Nov 17 '15 at 10:25

XSLT: How to check equality of children

2 Answers2