XSD的独特元素和属性

Question

everybody! This is my first question on stackoverflow, although I'm regularly reading posts on this site.

To get to the point, I'm trying to define an XML Schema that looks as following:

<xs:element name="keyConfiguration">
<xs:complexType>
  <xs:sequence>
    <xs:element name="move">
      <xs:complexType>
        <xs:attribute name="N" type="keyCode"/>
        <xs:attribute name="NE" type="keyCode"/>
        <xs:attribute name="E" type="keyCode"/>
        <xs:attribute name="SE" type="keyCode"/>
        <xs:attribute name="S" type="keyCode"/>
        <xs:attribute name="SW" type="keyCode"/>
        <xs:attribute name="W" type="keyCode"/>
        <xs:attribute name="NW" type="keyCode"/>
      </xs:complexType>
    </xs:element>
    <xs:element name="wait" type="keyCode"/>
    <xs:element name="select" type="keyCode"/>
  </xs:sequence>
</xs:complexType>
<xs:unique name="uniqueKeyCode">
  <xs:selector xpath="."/>
  <xs:field xpath="move/@*"/>
  <xs:field xpath="wait"/>
  <xs:field xpath="select"/>
</xs:unique>

The keyCode is an enumeration type used to identify keyboard presses and it accepts a subset of xs:int .

The idea is that I don't want to validate XML files that map multiple possible actions to the same key, so the following XML should be invalid:

<keyConfiguration>
  <move N="101" NE="101" E="102" SE="99" S="98" SW="97" W="100" NW="103"/>
  <wait>101</wait>
  <select>101</select>
</keyConfiguration>

Both attributes for moving to North, North-East etc. and elements for wait/select actions are repeated and none should happen. All atrributes for move directions and all elements for other actions should be unique.

Sadly, when I try to validate the given XML against the XSD, it is valid! I think the XPath's in the unique tag are broken, but I don't know how to fix this (I tried multiple variants, including <xs:field xpath="*/move/@*"/> and <xs:field xpath="*/wait"/> and it still didn't work).

Thanks in advance!

Edit: here is the full schema definition, if it helps:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:simpleType name="keyCode">
    <xs:restriction base="xs:int">
      <xs:enumeration value="10"/> <!-- Enter -->
      ...
      <xs:enumeration value="96"/> <!-- NumPad-0 -->
      <xs:enumeration value="97"/> <!-- NumPad-1 -->
      <xs:enumeration value="98"/> <!-- NumPad-2 -->
      <xs:enumeration value="99"/> <!-- NumPad-3 -->
      <xs:enumeration value="100"/> <!-- NumPad-4 -->
      <xs:enumeration value="101"/> <!-- NumPad-5 -->
      <xs:enumeration value="102"/> <!-- NumPad-6 -->
      <xs:enumeration value="103"/> <!-- NumPad-7 -->
      <xs:enumeration value="104"/> <!-- NumPad-8 -->
      <xs:enumeration value="105"/> <!-- NumPad-9 -->
      ...
      </xs:restriction>
  </xs:simpleType>

  <xs:element name="keyConfiguration">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="move">
          <xs:complexType>
            <xs:attribute name="N" type="keyCode"/>
            <xs:attribute name="NE" type="keyCode"/>
            <xs:attribute name="E" type="keyCode"/>
            <xs:attribute name="SE" type="keyCode"/>
            <xs:attribute name="S" type="keyCode"/>
            <xs:attribute name="SW" type="keyCode"/>
            <xs:attribute name="W" type="keyCode"/>
            <xs:attribute name="NW" type="keyCode"/>
          </xs:complexType>
        </xs:element>
        <xs:element name="wait" type="keyCode"/>
        <xs:element name="select" type="keyCode"/>
      </xs:sequence>
    </xs:complexType>
    <xs:unique name="uniqueKeyCode">
    <xs:selector xpath="."/>
      <xs:field xpath="*/move/@*"/>
      <xs:field xpath="*/wait"/>
      <xs:field xpath="*/select"/>
    </xs:unique>
  </xs:element>
</xs:schema>

Maybe it has something to do with the namespace? I tried looking on the web for with xpath examples, but I couldn't find anything that would help me identify the problem. Thanks!

Answer 1

I don't think this can be done using XSD 1.0. Unique works this way: xs:selector selects a set of elements across wich the fields value should be unique.

So, in the selector you should select every attribute, the value of and the value of , and in the field the value of those nodes (dot character "."). Have in mind that in XPath the operator | gives the union between node-sets. Ideally you could use this to solve your problem:

<xs:unique name="uniqueKeyCode">
    <xs:selector xpath="move/@* | wait | select"/>
    <xs:field xpath="."/>
</xs:unique>

However XSD does not allows to select attributes in xs:selector . But I hope you understand that if N , NE , W , etc were elemnts instead of attributes you are allowed to use something like the following and it will work:

<xs:unique name="uniqueKeyCode">
    <xs:selector xpath="move/* | wait | select"/>
    <xs:field xpath="."/>
</xs:unique>

And this will work because you are only selecting elements in xs:selector.

Using XSD 1.1 this can be done using xs:assert, that allows you to use xpath (selector, field, unique, etc only allows you to use a restricted XPath subset). Example assertion that will solve this problem:

<xs:assert test="count(distinct-values(move/@* | wait | select)) = count(move/@* | wait | select)"/>

---

In addition have in mind that is easier to define the keyCode type using ranges (from 10 to 105) and using unions (from 10 to 50 + from 60 to 105) rather than using xs:enumeration.

Example for continuos values:

<xs:simpleType name="keyCode">
    <xs:restriction base="xs:int">
        <xs:minInclusive value="10"/>
        <xs:maxInclusive value="105"/>
    </xs:restriction>
</xs:simpleType>

Example for non continuous values:

<xs:simpleType name="keyCode">
    <xs:union>
        <xs:simpleType>
            <xs:restriction base="xs:int">
                <xs:minInclusive value="10"/>
                <xs:maxInclusive value="50"/>
            </xs:restriction>
        </xs:simpleType>

        <xs:simpleType>
            <xs:restriction base="xs:int">
                <xs:minInclusive value="60"/>
                <xs:maxInclusive value="105"/>
            </xs:restriction>
        </xs:simpleType>
    </xs:union>
</xs:simpleType>