1

I have a XML which reads

<Options>
  <option1>Y</option1>
  <option2>N</option2>
  <option3>N</option3>
</Options>

I would like to ensure only one child element (of Options) has value Y so that above XML is valid but not the below one.

<Options>
  <option1>Y</option1>
  <option2>Y</option2>
  <option3>N</option3>
</Options>

I tried unique and referential integrity but couldn't work out.

Any help/idea much appreciated.

Dijkgraaf
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Milind Thakkar
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1 Answers1

1

You'd have to enforce such a constraint outside of XSD 1.0, but you could use xs:assert to enforce it with XSD 1.1:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema attributeFormDefault="unqualified" 
  elementFormDefault="qualified" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning"
  vc:minVersion="1.1">

  <xs:element name="Options">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="option1"/>
        <xs:element name="option2"/>
        <xs:element name="option3"/>
      </xs:sequence>
      <xs:assert test="count(* = 'Y') = 1"/>
    </xs:complexType>
  </xs:element>
 </xs:schema>

Or, to avoid separately naming each option:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema attributeFormDefault="unqualified" 
  elementFormDefault="qualified" 
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning"
  vc:minVersion="1.1">

  <xs:element name="Options">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="option" maxOccurs="unbounded" />
      </xs:sequence>
      <xs:assert test="count(option = 'Y') = 1"/>
    </xs:complexType>
  </xs:element>
 </xs:schema>

Constraining options to be only Y or N could of course also been done if desired.

kjhughes
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  • Thanks. Is there anyway without assert? Also, is XSD 1.1 is supported by major processor? I tried using assert in Visual Studio 2013, but it didn't work. Any free tools where I can verify XML against XSD 1.1 schema? – Milind Thakkar Jan 11 '15 at 18:09
  • As I mentioned, you'll need XSD 1.1 if you want to do it within XSD. For a list of processors that support XSD 1.1, see [**this answer**](http://stackoverflow.com/a/19818871/290085). Thanks. – kjhughes Jan 11 '15 at 18:24