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xmlxsdxsd-validation
Fyntasia
Fyntasia

Reputation: 1143

XSD: Unique ID across all nodes

I'm struggling with an XSD that should apply a unique constraint to all my categories.

Each of my categories can have children which, in turn, are categories. This is what the "Category" portion of my XSD looks like;

<xsd:element name="Categories">
    <xsd:complexType>
        <xsd:sequence>
            <xsd:element name="Category" maxOccurs="unbounded" type="Category"/>
        </xsd:sequence>
    </xsd:complexType>
    <xsd:unique name="CategoryUnique">
        <xsd:selector xpath="Category"/>
        <xsd:field xpath="ID"/>
    </xsd:unique>
</xsd:element>

And the "Category" type:

<xsd:complexType name="Category">
    <xsd:all>
        <xsd:element name="ID" type="xsd:unsignedInt"/>
        <xsd:element name="Title" type="xsd:string"/>
        <xsd:element name="Children" minOccurs="0">
            <xsd:complexType>
                <xsd:sequence>
                    <xsd:element name="Category" type="Category" maxOccurs="unbounded"/>
                </xsd:sequence>
            </xsd:complexType>
            <xsd:unique name="CategoryChildUnique">
                <xsd:selector xpath="Category"/>
                <xsd:field xpath="ID"/>
            </xsd:unique>
        </xsd:element>
    </xsd:all>
</xsd:complexType>

This XSD handles the following things correctly:

  1. Prevents multiple "Category" nodes on the "Categories" level from having identical ID's,
  2. Prevents children in the same parent node from having identical ID's

How do I make sure ANY "Category" node can't have the same ID as any other "Category" node in the same parent container (the "Categories" node is contained in a wrapper)

Upvotes: 0

Views: 363

Answers (1)

Fyntasia
Fyntasia

Reputation: 1143

I've solved this problem!

After a lot of attempts with all additions I could think of, I've figured out how to make the XSD check all the child nodes!

<xsd:unique name="CategoriesUnique">
    <xsd:selector xpath=".//Category"/>
    <xsd:field xpath="ID"/>
</xsd:unique>

This replaces the unique constraint in the "Categories" node and all subsequent category nodes are checked!

Check W3Schools for information about the Xpath syntax:

// Selects nodes in the document from the current node that match the selection no matter where they are.

. Selects the current node

Upvotes: 2

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