How do I write "if elsif" conditions using basic XPath?

Question

I have a very basic XML and wanted to write an Xpath query to get a value. Here is XML:

<?xml version="1.0" encoding="UTF-8"?>
<person>
    <address>
        <type>STD</type>
        <key>1234</key>
    </address>
    <address>
        <type>BA</type>
        <key>1234</key>
    </address>
    <phone>
        <type>TEL</type>
        <key>1234</key>
        <telephonenum>7</num>
    </phone>
    <phone>
        <type>TEL</type>
        <key>1234</key>
        <telephonenum>8</num>
    </phone>
    <phone>
        <type>TEL</type>
        <key>1234</key>
        <telephonenum>9</num>
    </phone>
</person>

Here are the conditions I have:

If (/person/address[type = "STD"]/addresskey = and /person/address[type = "BA"/addresskey )

then I should get the /person/phone[2]/telephonenum. If this second telephone number doesn't exist then it should get the first telephone number.

Answer 1

Here are the conditions I have:

If (/person/address[type = "STD"]/addresskey = and /person/address[type = "BA"/addresskey )

then I should get the /person/phone[2]/telephonenum. If this second telephone number doesn't exist then it should get the first telephone number.

I guess that by addresskey you mean just key (there is no addresskey element in the provided XML).

Also, the XML is not wellformed and I had to correct ie.

Now let us address the stated requirements:

First:

I should get the /person/phone[2]/telephonenum.

Translates to this:

/*/phone[2]

Then:

If this second telephone number doesn't exist then it should get the first telephone number.

Modifies the above expression to this:

/*/phone[not(position() >2)][last()]

Finally:

If (/person/address[type = "STD"]/addresskey = and /person/address[type = "BA"/addresskey )

the complete expression becomes:

/*/phone[not(position() >2)][last()]
            [/*/address[type = 'STD']/key
            =
             /*/address[type = 'BA']/key
            ]

XSLT - based verification:

<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:template match="/">
  <xsl:copy-of select=
   "/*/phone[not(position() >2)][last()]
         [/*/address[type = 'STD']/key
         =
          /*/address[type = 'BA']/key
         ]
   "/>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the provided (and corrected) XML:

<person>
    <address>
        <type>STD</type>
        <key>1234</key>
    </address>
    <address>
        <type>BA</type>
        <key>1234</key>
    </address>
    <phone>
        <type>TEL</type>
        <key>1234</key>
        <telephonenum>7</telephonenum>
    </phone>
    <phone>
        <type>TEL</type>
        <key>1234</key>
        <telephonenum>8</telephonenum>
    </phone>
    <phone>
        <type>TEL</type>
        <key>1234</key>
        <telephonenum>9</telephonenum>
    </phone>
</person>

the wanted node is selected and output:

<phone>
   <type>TEL</type>
   <key>1234</key>
   <telephonenum>8</telephonenum>
</phone>

---

II. XPath 2.0 expression:

for $check in
      /*/address[type = 'STD']/key[1]
     eq
      /*/address[type = 'BA']/key[1],
    $p1 in /*[$check]/phone[1],
    $p2 in /*[$check]/phone[2]
 return
   ($p2, $p1)[1]