Question

I’ve been trying to get the UNIQUE constraint placed on some attributes I have in a fairly basic XSD Schema. I’m using XMLSpy and i’m wanting to put a unique constraint around TEMPLATE.ID for my nodes (i.e. it’s important that they remain unique).

I’ve put the below in place and tried the following:

Secenario 1

<xs:unique name="uniqueviewid">
  <xs:selector xpath="./views"/>
  <xs:field xpath="@id"/>
</xs:unique>

Result:
XSD: Validates Ok. XML Validates but doesn’t uphold the unique constraint (ie two or more elements with the same id aren’t picked up

Scenario 2

<xs:unique name="uniqueviewid">
  <xs:selector xpath="views"/>
  <xs:field xpath="@id"/>
</xs:unique>

**Results* Same as Scenario 1. XSD Validates, XML Validates but ignores duplicate @id in view element

Scenario 3

<xs:unique name="uniqueviewid">
  <xs:selector xpath="*"/>
  <xs:field xpath="@id"/>
</xs:unique>

Results: XSD Validates and XML Validats and it respects the UNIQUE constrint (ie if duplicate views with @id it throws an invaldation as per design).

Problem is that the wild card is “*” which means all subnodes under VIEWPODS will be validated, which isnot what I want. I instead want the contraint to be focused on VIEWPOS/VIEWS/@ID exact path.

I think my XPATH is all wrong but i can’t think of what i’m doing specifically wrong?

---

The example XML.

This is the example XML.

<config xmlns="http://tempuri.org/RIAGenicConfig.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://tempuri.org/RIAGenicConfig.xsd RIAGenicConfig.xsd">
  <view>
    <viewpods>
      <views id="view1"/>
      <views id="view1"/>
    </viewpods>
  </view>
</config>

The XSD in Question.

<xs:schema xmlns="http://tempuri.org/RIAGenicConfig.xsd" xmlns:mstns="http://tempuri.org/RIAGenicConfig.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://tempuri.org/RIAGenicConfig.xsd" elementFormDefault="qualified" id="RIAGenicConfig">
  <xs:element name="config">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="view">
          <xs:complexType>
            <xs:choice>
              <xs:element name="viewpods">
                <xs:complexType>
                  <xs:choice>
                    <xs:element name="views" maxOccurs="unbounded">
                      <xs:complexType>
                        <xs:attribute name="id"/>
                      </xs:complexType>
                    </xs:element>
                    <xs:element name="blah"/>
                  </xs:choice>
                </xs:complexType>
                <xs:unique name="uniqueviewid">
                  <xs:selector xpath="*"/>
                  <xs:field xpath="@id"/>
                </xs:unique>
              </xs:element>
            </xs:choice>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

Answer 1

Qualify the xpath selection for mstns:views instead of *(all elements):

<xs:unique name="uniqueviewid">
  <xs:selector xpath="mstns:views"/>
   <xs:field xpath="@id"/>
</xs:unique>