XSD: How to validate the XML file according to value of some tag?

I was trying to validate this XML file .开发者_如何转开发.. where if

1. <tag1> is "Y" then <tag2> must appear

2. if <tag1> is "N" then <tag2> must not appear ..

   <parent>
     <a>
       <tag1>Y</tag1>
       <tag2>sometext</tag2>
     </a>
     <a>
       <tag1>N</tag1>
     </a>
   </parent>
   

I tried <choice> tag but doesn't seem to work .. :( I have come to conclusion that this feature is not available in XSD ..

Can you guide me atleast some alternative to implement this ? by the way I am using Visual Studio 2005 ..

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You cannot validate things like that with XSD.

XML schema is not designed and not intended to check "intra-tag" relationships, e.g. "tag2 must be present if tag1's value is 'Y'" - just cannot be done, sorry.

If you need to check these kind of conditions, you'll have to look at Schematron to do that.

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It's a known fact that this is a handycap of XML schema. But I would appreciate your approach of trying the <choice> tag. It could be successful if your conditions were something like this:

1. If <tag1> is required and appears first then <tag2> isn't required (and appears as second tag)
2. If <tag2> is required and appears first then <tag1> isn't required (and appears as second)

The code is:

<xs:element name="parent">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="a" maxOccurs="unbounded">
        <xs:complexType>
          <xs:choice>
            <xs:sequence>
              <xs:element name="tag1" type="xs:boolean" />
              <xs:element name="tag2" type="xs:string" minOccurs="0" />
            </xs:sequence>
            <xs:sequence>
              <xs:element name="tag2" type="xs:string" />
              <xs:element name="tag1" type="xs:boolean" minOccurs="0" />
            </xs:sequence>
          </xs:choice>
        </xs:complexType>
      </xs:element>
    </xs:sequence>
  </xs:complexType>
</xs:element>

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Unfortunately this problem cannot be fixed using XSD. The reason is that XSD can only be used to define the structure (syntax) of XML-Files. What you would like to do is to couple the syntax to some semantic properties (some TAG must have a certain content to decide on the syntax of some TAGS nearby).

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Its not possible with XSD .. But by the way you can work around something like Infant-programmer if the requirement is bit comfortable as shown in her example ..