XSD for requiring elements with certain attributes

[monsterpot]

Hello,
I have a document like this:

<parameters>
<param ptype="init">somedata</param>
<param ptype="process">moredata</param>
<param ptype="kill">alsodata</param>
</parameters>

<param> has the following definition in my XSD:

<xs:complexType name="param">
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="ptype" type="xs:string" use="required" />
</xs:extension
</xs:simpleContent>
</xs:complexType>

The question I have is: I want to require <parameters> elements to
contain exactly 3 <param> elements, and furthermore, to require one
element with the attribute ptype="init", one element with
ptype="process", and another with ptype="kill".

So, for example I want to invalidate this document:

<parameters>
<param ptype="init">somedata</param>
<param ptype="kill">alsodata</param>
</parameters>

because it is missing an element with ptype="process".

I am somewhat new to XSD. Could someone help me?

 

[Martin Honnen]

I have a document like this:

<parameters>
<param ptype="init">somedata</param>
<param ptype="process">moredata</param>
<param ptype="kill">alsodata</param>
</parameters>

<param> has the following definition in my XSD:

<xs:complexType name="param">
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="ptype" type="xs:string" use="required" />
</xs:extension
</xs:simpleContent>
</xs:complexType>

The question I have is: I want to require <parameters> elements to
contain exactly 3 <param> elements,

That would be
<xsl:element name="parameters">
<xs:complexType>
<xs:sequence>
<xs:element ref="param" />
<xs:element ref="param" />
<xs:element ref="param" />
</xs:sequence>
</xs:complexType>

and furthermore, to require one
element with the attribute ptype="init", one element with
ptype="process", and another with ptype="kill".

I don't think you can model such a constraint with a W3C XML schema.
There you would need to use different kinds of child elements e.g.
<parameters>
<init>somedata</init>
<process>moredata</process>
<kill>alsodata</kill>
</parameters>
and model that as a sequence.

Or you could do as suggested earlier above and model your additional
constraints in a schema language more suitable, schematron, see
<http://xml.ascc.net/resource/schematron/schematron.html>
there you could specify a constraint on the attributes.

 

[Stan Kitsis [MSFT]]

The following schema will do what you need. It defines a sequence with
three occurrences of param element and then uses a uniqueness constraint to
enforce unique attributes.

<?xml version="1.0" encoding="utf-8" ?>

<xs:schema targetNamespace="http://myschemas/foo"

elementFormDefault="qualified"

xmlns:foo="http://myschemas/foo"

xmlns="http://myschemas/foo"

xmlns:xs="http://www.w3.org/2001/XMLSchema">



<xs:complexType name="paramType">

<xs:simpleContent>

<xs:extension base="xs:string">

<xs:attribute name="ptype" type="paramAttrType" use="required" />

</xs:extension>

</xs:simpleContent>

</xs:complexType>



<xs:simpleType name="paramAttrType">

<xs:restriction base="xs:string">

<xs:enumeration value="init"/>

<xs:enumeration value="process"/>

<xs:enumeration value="kill"/>

</xs:restriction>

</xs:simpleType>



<xs:complexType name="paramsType">

<xs:sequence>

<xs:element name="param" minOccurs="3" maxOccurs="3"
type="paramType"/>

</xs:sequence>

</xs:complexType>



<xs:element name="params" type="paramsType">

<xs:unique name="uniqueParams">

<xs:selector xpath="fooaram"/>

<xs:field xpath="@ptype"/>

</xs:unique>

</xs:element>

</xs:schema>


--
Stan Kitsis
Program Manager, XML Technologies
Microsoft Corporation

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