XML Schema (XSD)
<xs:choice>
A model group that selects one of its child particles each time the group occurs.
choice expresses alternatives, not unordered children. With its default occurrence range, exactly one branch is selected.
Set minOccurs=0 to make the whole decision optional, or raise maxOccurs when several branch selections may appear in sequence.
- Format
- XML Schema (XSD)
- Namespace
- XML Schema Definition (XSD)
- How many
- Zero or one as a primary model group; it may be nested and repeated.
What our validator does
The XML validator checks well-formedness and selected SOAP or XML Schema vocabulary rules. It reports this content-model defect with a concrete repair while staying silent on rules it cannot establish from one document.
Broken and fixed
Both documents below are well-formed XML — that is the point of this corpus — and both are run through the validator on every test run. The verdicts here are what it returned, not what we expect it to.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:example:catalog">
<xs:complexType name="Product"><xs:attribute name="active" type="xs:boolean" maxOccurs="2"/></xs:complexType>
</xs:schema>xs:attribute cannot use minOccurs or maxOccurs; attributes use the use attribute instead.<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tns="urn:example:catalog" targetNamespace="urn:example:catalog" elementFormDefault="qualified">
<xs:simpleType name="Sku"><xs:restriction base="xs:string"><xs:minLength value="1"/></xs:restriction></xs:simpleType>
<xs:complexType name="Product"><xs:sequence><xs:element name="sku" type="tns:Sku"/></xs:sequence><xs:attribute name="active" type="xs:boolean"/></xs:complexType>
<xs:element name="product" type="tns:Product"/>
</xs:schema>Where it reaches
- FormatsXML Schema (XSD)The XSD format page places this element in the complete document model.
- NamespacesXML Schema Definition (XSD)The exact namespace URI that gives <xs:choice> its vocabulary meaning.
- ToolsXSD validatorCheck schema-document structure before validating an instance against it.
Related elements
- <xs:sequence>A model group requiring child particles to occur in declared order, subject to each occurrence range.
- <xs:element>Declares an element's name, type, occurrence range, defaulting, and whether an explicit xsi:nil is allowed.
- <xs:complexType>Defines structured element content: child elements, attributes, mixed text, and derivation from another type.
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