Chapter 16

Substitution groups

Binding Test

Schema

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:annotation>
    <xsd:documentation>
      This example illustrates substitution groups.
    </xsd:documentation>
  </xsd:annotation>

  <xsd:element name="items" type="ItemsType"/>
  <xsd:complexType name="ItemsType">
    <xsd:sequence>
      <xsd:element ref="product" maxOccurs="unbounded"/>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:element name="product" type="ProductType"/>
  <xsd:complexType name="ProductType">
    <xsd:sequence>
      <xsd:element name="number" type="xsd:integer"/>
      <xsd:element name="name" type="xsd:string"/>
    </xsd:sequence>
  </xsd:complexType>

  <xsd:element name="shirt" type="ShirtType"
                substitutionGroup="product"/>
  <xsd:complexType name="ShirtType">
    <xsd:complexContent>
      <xsd:extension base="ProductType">
        <xsd:sequence>
          <xsd:element name="size" type="ShirtSizeType"/>
          <xsd:element name="color" type="ColorType"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>

  <xsd:element name="hat" substitutionGroup="product">
  <xsd:complexType>
    <xsd:complexContent>
      <xsd:extension base="ProductType">
        <xsd:sequence>
          <xsd:element name="size" type="HatSizeType"/>
        </xsd:sequence>
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
  </xsd:element>

  <xsd:element name="umbrella" substitutionGroup="product"/>

  <xsd:complexType name="ShirtSizeType">
    <xsd:simpleContent>
      <xsd:extension base="xsd:integer">
        <xsd:attribute name="system" type="xsd:token"/>
      </xsd:extension>
    </xsd:simpleContent>
  </xsd:complexType>

  <xsd:complexType name="HatSizeType">
    <xsd:simpleContent>
      <xsd:extension base="xsd:token">
        <xsd:attribute name="system" type="xsd:token"/>
      </xsd:extension>
    </xsd:simpleContent>
  </xsd:complexType>

  <xsd:complexType name="ColorType">
    <xsd:attribute name="value" type="xsd:string"/>
  </xsd:complexType>

</xsd:schema>

XML Document

<items xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:noNamespaceSchemaLocation="chapter16.xsd">
  <product>
    <number>999</number>
    <name>Special Seasonal</name>
  </product>
  <shirt>
    <number>557</number>
    <name>Short-Sleeved Linen Blouse</name>
    <size>10</size>
    <color value="blue"/>
  </shirt>
  <hat>
    <number>563</number>
    <name>Ten-Gallon Hat</name>
    <size>L</size>
  </hat>
  <umbrella>
    <number>443</number>
    <name>Deluxe Golf Umbrella</name>
  </umbrella>
</items>

xsData XML Document

<items xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <umbrella>
    <number>443</number>
    <name>Deluxe Golf Umbrella</name>
  </umbrella>
  <hat>
    <number>563</number>
    <name>Ten-Gallon Hat</name>
    <size>L</size>
  </hat>
  <shirt>
    <number>557</number>
    <name>Short-Sleeved Linen Blouse</name>
    <size>10</size>
    <color value="blue"/>
  </shirt>
  <product>
    <number>999</number>
    <name>Special Seasonal</name>
  </product>
</items>

xsData JSON

{
    "umbrella": [
        {
            "any_element": {
                "qname": null,
                "text": null,
                "tail": null,
                "ns_map": {},
                "children": [
                    {
                        "qname": "number",
                        "text": "443",
                        "tail": null,
                        "ns_map": {
                            "xsi": "http://www.w3.org/2001/XMLSchema-instance"
                        },
                        "children": [],
                        "attributes": {}
                    },
                    {
                        "qname": "name",
                        "text": "Deluxe Golf Umbrella",
                        "tail": null,
                        "ns_map": {
                            "xsi": "http://www.w3.org/2001/XMLSchema-instance"
                        },
                        "children": [],
                        "attributes": {}
                    }
                ],
                "attributes": {}
            }
        }
    ],
    "hat": [
        {
            "number": 563,
            "name": "Ten-Gallon Hat",
            "size": {
                "value": "L",
                "system": null
            }
        }
    ],
    "shirt": [
        {
            "number": 557,
            "name": "Short-Sleeved Linen Blouse",
            "size": {
                "value": 10,
                "system": null
            },
            "color": {
                "value": "blue"
            }
        }
    ],
    "product": [
        {
            "number": 999,
            "name": "Special Seasonal"
        }
    ]
}

Example 16-1 The head of a substitution group

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="items" type="ItemsType" />
  <xs:complexType name="ItemsType">
    <xs:sequence>
      <xs:element ref="product" maxOccurs="unbounded" />
    </xs:sequence>
  </xs:complexType>
  <xs:element name="product" type="ProductType" />
  <xs:complexType name="ProductType">
    <xs:sequence>
      <xs:element name="number" type="xs:integer" />
      <xs:element name="name" type="xs:string" />
    </xs:sequence>
  </xs:complexType>
</xs:schema>

from dataclasses import dataclass, field
from typing import List, Optional


@dataclass
class ProductType:
    """
    :ivar number:
    :ivar name:
    """
    number: Optional[int] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )
    name: Optional[str] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )


@dataclass
class Product(ProductType):
    class Meta:
        name = "product"


@dataclass
class ItemsType:
    """
    :ivar product:
    """
    product: List[Product] = field(
        default_factory=list,
        metadata=dict(
            type="Element",
            min_occurs=1,
            max_occurs=9223372036854775807
        )
    )


@dataclass
class Items(ItemsType):
    class Meta:
        name = "items"

Example 16-2 Members of a substitution group

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:include schemaLocation="chapter16.xsd" />
  <xs:element name="shirt" type="ShirtType" substitutionGroup="product" />
  <xs:complexType name="ShirtType">
    <xs:complexContent>
      <xs:extension base="ProductType">
        <xs:sequence>
          <xs:element name="size" type="ShirtSizeType" />
          <xs:element name="color" type="xs:string" />
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>
  <xs:element name="hat" substitutionGroup="product">
    <xs:complexType>
      <xs:complexContent>
        <xs:extension base="ProductType">
          <xs:sequence>
            <xs:element name="size" type="HatSizeType" />
          </xs:sequence>
        </xs:extension>
      </xs:complexContent>
    </xs:complexType>
  </xs:element>
  <xs:element name="umbrella" substitutionGroup="product" />
</xs:schema>

from dataclasses import dataclass, field
from typing import Optional
from tests.fixtures.defxmlschema.chapter16.chapter16 import (
    HatSizeType,
    ProductType,
    ShirtSizeType,
)


@dataclass
class Umbrella:
    """
    :ivar any_element:
    """
    class Meta:
        name = "umbrella"

    any_element: Optional[object] = field(
        default=None,
        metadata=dict(
            type="Wildcard",
            namespace="##any",
            required=True
        )
    )


@dataclass
class ShirtType(ProductType):
    """
    :ivar size:
    :ivar color:
    """
    size: Optional[ShirtSizeType] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )
    color: Optional[str] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )


@dataclass
class Hat(ProductType):
    """
    :ivar size:
    """
    class Meta:
        name = "hat"

    size: Optional[HatSizeType] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )


@dataclass
class Shirt(ShirtType):
    class Meta:
        name = "shirt"

Example 16-4 Substitution group with simple types

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="number" />
  <xs:element name="skuNumber" type="xs:string" substitutionGroup="number" />
  <xs:element name="productID" type="xs:integer" substitutionGroup="number" />
</xs:schema>

from dataclasses import dataclass, field
from typing import Optional


@dataclass
class Number:
    """
    :ivar any_element:
    """
    class Meta:
        name = "number"

    any_element: Optional[object] = field(
        default=None,
        metadata=dict(
            type="Wildcard",
            namespace="##any",
            required=True
        )
    )


@dataclass
class ProductId:
    """
    :ivar value:
    """
    class Meta:
        name = "productID"

    value: Optional[int] = field(
        default=None,
        metadata=dict(
            required=True
        )
    )


@dataclass
class SkuNumber:
    """
    :ivar value:
    """
    class Meta:
        name = "skuNumber"

    value: Optional[str] = field(
        default=None,
        metadata=dict(
            required=True
        )
    )

Example 16-5 A member of two substitution groups

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:include schemaLocation="example1607.xsd" />
  <xs:element name="product" type="ProductType" />
  <xs:element name="discontinuedProduct" type="ProductType" />
  <xs:element name="hat" type="HatType" substitutionGroup="product" />
  <xs:element name="shirt" type="ShirtType" substitutionGroup="product" />
  <xs:element name="umbrella" type="UmbrellaType" substitutionGroup="product discontinuedProduct" />
</xs:schema>

from dataclasses import dataclass
from tests.fixtures.defxmlschema.chapter16.example1607 import (
    HatType,
    ShirtType,
    UmbrellaType,
)
from tests.fixtures.defxmlschema.chapter22.example2207 import (
    ProductType,
)


@dataclass
class DiscontinuedProduct(ProductType):
    class Meta:
        name = "discontinuedProduct"


@dataclass
class Hat(HatType):
    class Meta:
        name = "hat"


@dataclass
class Product(ProductType):
    class Meta:
        name = "product"


@dataclass
class Shirt(ShirtType):
    class Meta:
        name = "shirt"


@dataclass
class Umbrella(UmbrellaType):
    class Meta:
        name = "umbrella"

Example 16-6 Using a choice group

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:include schemaLocation="../chapter16/example1607.xsd" />
  <xs:element name="items" type="ItemsType" />
  <xs:complexType name="ItemsType">
    <xs:group ref="ProductGroup" maxOccurs="unbounded" />
  </xs:complexType>
  <xs:group name="ProductGroup">
    <xs:choice>
      <xs:element name="product" type="ProductType" />
      <xs:element name="shirt" type="ShirtType" />
      <xs:element name="hat" type="HatType" />
      <xs:element name="umbrella" type="ProductType" />
    </xs:choice>
  </xs:group>
</xs:schema>

from dataclasses import dataclass, field
from typing import List
from tests.fixtures.defxmlschema.chapter16.example1607 import (
    HatType,
    ShirtType,
)
from tests.fixtures.defxmlschema.chapter22.example2207 import (
    ProductType,
)


@dataclass
class ItemsType:
    """
    :ivar product:
    :ivar shirt:
    :ivar hat:
    :ivar umbrella:
    """
    product: List[ProductType] = field(
        default_factory=list,
        metadata=dict(
            type="Element",
            namespace="",
            min_occurs=0,
            max_occurs=9223372036854775807
        )
    )
    shirt: List[ShirtType] = field(
        default_factory=list,
        metadata=dict(
            type="Element",
            namespace="",
            min_occurs=0,
            max_occurs=9223372036854775807
        )
    )
    hat: List[HatType] = field(
        default_factory=list,
        metadata=dict(
            type="Element",
            namespace="",
            min_occurs=0,
            max_occurs=9223372036854775807
        )
    )
    umbrella: List[ProductType] = field(
        default_factory=list,
        metadata=dict(
            type="Element",
            namespace="",
            min_occurs=0,
            max_occurs=9223372036854775807
        )
    )

Example 16-7 Defining derived types

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:include schemaLocation="../chapter22/example2207.xsd" />
  <xs:complexType name="ShirtType">
    <xs:complexContent>
      <xs:extension base="ProductType">
        <xs:sequence>
          <xs:element name="size" type="xs:int" />
          <xs:element name="color" type="xs:string" />
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>
  <xs:complexType name="HatType">
    <xs:complexContent>
      <xs:extension base="ProductType">
        <xs:sequence>
          <xs:element name="size" type="xs:int" />
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>
  <xs:complexType name="UmbrellaType">
    <xs:complexContent>
      <xs:extension base="ProductType" />
    </xs:complexContent>
  </xs:complexType>
</xs:schema>

from dataclasses import dataclass, field
from typing import Optional
from tests.fixtures.defxmlschema.chapter22.example2207 import (
    ProductType,
)


@dataclass
class HatType:
    """
    :ivar number:
    :ivar name:
    :ivar size:
    """
    number: Optional[int] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )
    name: Optional[str] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )
    size: Optional[int] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )


@dataclass
class ShirtType:
    """
    :ivar number:
    :ivar name:
    :ivar size:
    :ivar color:
    """
    number: Optional[int] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )
    name: Optional[str] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )
    size: Optional[int] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )
    color: Optional[str] = field(
        default=None,
        metadata=dict(
            type="Element",
            namespace="",
            required=True
        )
    )


@dataclass
class UmbrellaType(ProductType):
    pass

Example 16-9 Using final to control substitution group declaration

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:include schemaLocation="example1606.xsd" />
  <xs:include schemaLocation="../chapter13/example13011.xsd" />
  <xs:element name="product" type="ProductType" final="#all" />
  <xs:element name="items" type="ItemsType" final="extension" />
  <xs:element name="color" type="xs:string" final="restriction" />
  <xs:element name="size" type="SizeType" final="" />
</xs:schema>

from dataclasses import dataclass, field
from typing import Optional
from tests.fixtures.defxmlschema.chapter16.example1606 import (
    ItemsType,
)
from tests.fixtures.defxmlschema.chapter22.example2207 import (
    ProductType,
)
from tests.fixtures.defxmlschema.chapter13.example13011 import (
    SizeType,
)


@dataclass
class Color:
    """
    :ivar value:
    """
    class Meta:
        name = "color"

    value: Optional[str] = field(
        default=None,
        metadata=dict(
            required=True
        )
    )


@dataclass
class Items(ItemsType):
    class Meta:
        name = "items"


@dataclass
class Product(ProductType):
    class Meta:
        name = "product"


@dataclass
class Size(SizeType):
    class Meta:
        name = "size"

Example 16-10 Using block to prevent substitution group use

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:include schemaLocation="example1607.xsd" />
  <xs:element name="product" type="ProductType" block="#all" />
  <xs:element name="hat" type="HatType" block="substitution" />
</xs:schema>

from dataclasses import dataclass
from tests.fixtures.defxmlschema.chapter16.example1607 import (
    HatType,
)
from tests.fixtures.defxmlschema.chapter22.example2207 import (
    ProductType,
)


@dataclass
class Hat(HatType):
    class Meta:
        name = "hat"


@dataclass
class Product(ProductType):
    class Meta:
        name = "product"

Samples Source

Definitive XML Schema by Priscilla Walmsley (c) 2012 Prentice Hall PTR