CODEWITHSUNDEEP
xmlnestedxqueryparentflwor
Srikrishna Pothukuchi
Srikrishna Pothukuchi

Reputation: 41

Sorting in XQuery: Nested FLWOR

I am trying to sort an XML document using XQuery. First level sorting is by one of the parent element.

And the second level sorting is one of the linked child element.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<FEATURES xmlns="http://www.example.com/" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <FEATURE>
        <abbreviation>CANAL</abbreviation>
        <LINKED_PROPERTIES>
            <LP>
                <abbreviation>zltinf</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>altalt</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>betbet</abbreviation>
                <category>C</category>
                <remarks />
            </LP>
        </LINKED_PROPERTIES>
        <description>Water Canal</description>
        <code>23</code>
        <relation_type />
    </FEATURE>
    <FEATURE>
        <abbreviation>AREA</abbreviation>
        <LINKED_PROPERTIES>
            <LP>
                <abbreviation>zltzlt</abbreviation>
                <category>A</category>
                <remarks>zolt zolt</remarks>
            </LP>
            <LP>
                <abbreviation>altalt</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>betbet</abbreviation>
                <category>C</category>
                <remarks />
            </LP>
        </LINKED_PROPERTIES>
        <description>Area under administration</description>
        <code>1</code>
        <relation_type />
    </FEATURE>
    <FEATURE>
        <abbreviation>BUOY</abbreviation>
        <LINKED_PROPERTIES>
            <LP>
                <abbreviation>zltinf</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>altalt</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>betbet</abbreviation>
                <category>C</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>infinf</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>altalt</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>betbet</abbreviation>
                <category>C</category>
                <remarks />
            </LP>
        </LINKED_PROPERTIES>
        <description>Buoy on water</description>
        <code>18</code>
        <relation_type />
    </FEATURE>
    <FEATURE>
        <abbreviation>DRONE</abbreviation>
        <LINKED_PROPERTIES>
            <LP>
                <abbreviation>zltinf</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>beltam</abbreviation>
                <category>A</category>
                <remarks />
            </LP>
            <LP>
                <abbreviation>betbet</abbreviation>
                <category>C</category>
                <remarks />
            </LP>
        </LINKED_PROPERTIES>
        <description>Drones Inland</description>
        <code>2</code>
        <relation_type />
    </FEATURE>
</FEATURES>

This document contains features of two levels, which belongs to a standard. So obviously I cannot modify the XML document. Above data is anonymized data.

My XQuery is like the below. 

<FEATURES xmlns="http://www.example.com/" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    {
    let $doc := doc("features.xml")
    for $feature in $doc/FEATURES/FEATURE
    order by $feature/abbreviation ascending
    return
    <FEATURE>
        {
        for $ft in $feature
        return if ($ft/child::element/name() eq
        "LINKED_PROPERTIES")then
        <LINKED_PROPERTIES_XXXXXXXX>{
            for $lp in $ft/LINKED_PROPERTIES/LP
            order
            by $lp/abbreviation ascending
            return $lp
            }
        </LINKED_PROPERTIES_XXXXXXXX>
        else $ft/*}
    </FEATURE>
    }
</FEATURES>

I am unable to get the proper equality condition at the child level and hence not getting desired sorting at the child level.

I do not want to go back to DOM/XSL for several reasons. Please assist.

Upvotes: 0

Views: 431

Answers (2)

Ghislain Fourny
Ghislain Fourny

Reputation: 7279

The inner for needs to iterate on the children of the feature, otherwise there will be only one item to iterate on. Also, further down in the tree, LINKED_PROPERTIES must be removed as $ft is already at that node, and other children must be returned as they are. Finally, the kind test was not quite right (must be child::element()).

<FEATURES xmlns="http://www.example.com/"
         xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">{
  let $doc := doc("features.xml")
  for $feature in $doc/FEATURES/FEATURE
  order by $feature/abbreviation ascending
  return <FEATURE>{
    for $ft-child in $feature/child::element()
    return if ($ft-child/name() eq "LINKED_PROPERTIES")
           then <LINKED_PROPERTIES_XXXXXXXX>{
             for $lp in $ft-child/LP
             order by $lp/abbreviation ascending
             return $lp
            }</LINKED_PROPERTIES_XXXXXXXX>
            else $ft-child
  }</FEATURE>
}</FEATURES>

The above query succeeds in oXygen.

Upvotes: 1

har07
har07

Reputation: 89285

If you meant to test if FEATURE has chid element LINKED_PROPERTIES :

return if ($ft/LINKED_PROPERTIES) then 
    <LINKED_PROPERTIES_XXXXXXXX>
    {
        .....
    }
    </LINKED_PROPERTIES_XXXXXXXX>

Your XQuery attempt for the same doesn't make much sense, it will never evaluates to true since it looks for child element named element ($ft/child::element) and further test if the element name equals "LINKED_PROPERTIES" (/name() eq "LINKED_PROPERTIES").

Upvotes: 0

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