XML Schema restriction element

XSD Element

Definition and usage

The restriction element defines constraints for simpleType, simpleContent, or complexContent.

Element information

Occurrence Once
Parent element complexContent
Content group, all, choice, sequence, attribute, attributeGroup, anyAttribute

Grammar

<restriction
id=ID
base=QName
any attributes
>
Content for simpleType:
(annotation?,(simpleType?,(minExclusive|minInclusive| 
maxExclusive|maxInclusive|totalDigits|fractionDigits|
length|minLength|maxLength|enumeration|whiteSpace|pattern)*))
Content for simpleContent:
(annotation?,(simpleType?,(minExclusive |minInclusive| 
maxExclusive|maxInclusive|totalDigits|fractionDigits|
(length|minLength|maxLength|enumeration|whiteSpace|pattern)*)?, 
((attribute|attributeGroup)*,anyAttribute?)
Content for complexContent:
(annotation?,(group|all|choice|sequence)?,
((attribute|attributeGroup)*,anyAttribute?)
</restriction>

(? The symbol indicates that the element can appear zero or one time in the restriction element.)

Attributes Description
id Optional. Specifies the unique ID of the element.
base Required. Specifies the names of the built-in data types, simpleType, or complexType elements defined in the schema (or in another schema indicated by the specified namespace).
any attributes Optional. Specifies any other attributes with a non-schema namespace.

Instance

Example 1

The following example defines an element named "age" with constraints. The value of age cannot be less than 0 or greater than 100:

<xs:element name="age">
  <xs:simpleType>
    <xs:restriction base="xs:integer">
      <xs:minInclusive value="0"/>
      <xs:maxInclusive value="100"/>
    </xs:restriction>
  </xs:simpleType>
</xs:element>

Example 2

This example defines an element named "initials". The "initials" element is a constrained simple type. Acceptable values are three uppercase or lowercase letters from a to z:

<xs:element name="initials">
  <xs:simpleType>
    <xs:restriction base="xs:string">
      <xs:pattern value="[a-zA-Z][a-zA-Z][a-zA-Z]"/>
    </xs:restriction>
  </xs:simpleType>
</xs:element>

Example 3

This example defines an element named "password". The "password" element is a constrained simple type. The value must be at least 5 characters and at most 8 characters long:

<xs:element name="password">
  <xs:simpleType>
    <xs:restriction base="xs:string">
      <xs:minLength value="5"/>
      <xs:maxLength value="8"/>
    </xs:restriction>
  </xs:simpleType>
</xs:element>

Example 4

This example demonstrates a complex type definition using constraints. The complex type "Chinese_customer" is derived from a common "customer" complex type, with the fixed value of the "country" element being "China":

<xs:complexType name="customer">
  <xs:sequence>
    <xs:element name="firstname" type="xs:string"/>
    <xs:element name="lastname" type="xs:string"/>
    <xs:element name="country" type="xs:string"/>
  </xs:sequence>
</xs:complexType>
<xs:complexType name="Chinese_customer">
  <xs:complexContent>
    <xs:restriction base="customer">
      <xs:sequence>
        <xs:element name="firstname" type="xs:string"/>
        <xs:element name="lastname" type="xs:string"/>
        <xs:element name="country" type="xs:string" fixed="China"/>
      </xs:sequence>
    </xs:restriction>
  </xs:complexContent>
</xs:complexType>

XSD Element