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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)
Parent
<xs:complexType><xs:sequence><xs:choice>
How many
Zero or one as a primary model group; it may be nested and repeated.

What it contains

Attributes

  • minOccursoptionalSet to zero when selecting no branch is valid.
  • maxOccursoptionalControls how many branch selections may occur.

Cardinality and constraints

Zero or one as a primary model group; it may be nested and repeated.

  • One branch is selected per occurrence.
  • It does not allow child elements in arbitrary order.

What our validator does

The XML validator checks that both examples are well-formed. It does not enforce this vocabulary's semantic content model, so the broken example is intentionally reported as valid XML.

We do not catch this one

This document is well-formed XML but violates a SOAP or XML Schema vocabulary rule. XML syntax alone cannot detect that defect; use a SOAP-aware processor or an XSD validator when conformance matters.

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.

broken
<?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>
No issue reported. This defect passes our checks.
fixed
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" 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="Sku"/></xs:sequence><xs:attribute name="active" type="xs:boolean"/></xs:complexType>
  <xs:element name="product" type="Product"/>
</xs:schema>
No errors. Warnings may remain — a conforming feed can still be missing a self link — but nothing here is wrong.

Where it reaches

Related elements

All 49 elements

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