XML Schema restrictions are not reflected within __dataclass_fields__ due to inheritance

[skinkie]

I have yesterday encountered a situation where there was a presumable recursive definition of an object. NeTEx-CEN/NeTEx#526 I have learned this definitionis actually prevented by an XML Schema restriction, which implicitly removes the fields that are not in use. xsData seems to do the right job, but for anyone that is using inspection on the dataclasses is faced with inheritance from the subsitutionGroup.

        <xsd:element name="AlternativeText" substitutionGroup="VersionedChild">
                <xsd:annotation>
                        <xsd:documentation>Alternative Text. +v1.1</xsd:documentation>
                </xsd:annotation>
                <xsd:complexType>
                        <xsd:complexContent>
                                <xsd:restriction base="AlternativeText_VersionedChildStructure">
                                        <xsd:sequence>
                                                <xsd:sequence>
                                                        <xsd:element name="DataManagedObjectRef" type="VersionOfObjectRefStructure" minOccurs="0">
                                                                <xsd:annotation>
                                                                        <xsd:documentation>Object for  attribute for which ALTERNATIVE TEXTprovides an alias. May be omitted if given by context.</xsd:documentation>
                                                                </xsd:annotation>
                                                        </xsd:element>
                                                        <xsd:element name="Text" type="MultilingualString">
                                                                <xsd:annotation>
                                                                        <xsd:documentation>Name of the entity.</xsd:documentation>
                                                                </xsd:annotation>
                                                        </xsd:element>
                                                </xsd:sequence>
                                        </xsd:sequence>
                                        <xsd:attribute name="id" type="AlternativeTextIdType" use="optional">
                                                <xsd:annotation>
                                                        <xsd:documentation>Identifier of ENTITY.</xsd:documentation>
                                                </xsd:annotation>
                                        </xsd:attribute>
                                        <xsd:attribute name="attributeName" type="xsd:NCName">
                                                <xsd:annotation>
                                                        <xsd:documentation>Name of text attribute for which this is the  alternative tex. Must be an existing attribute name </xsd:documentation>
                                                </xsd:annotation>
                                        </xsd:attribute>
                                </xsd:restriction>
                        </xsd:complexContent>
                </xsd:complexType>
        </xsd:element>

Is transformed into:

@dataclass(unsafe_hash=True, kw_only=True)
class AlternativeTextVersionedChildStructure(VersionedChildStructure):
    """
    Type for ALTERNATIVE TEXT.

    :ivar data_managed_object_ref: Object for  attribute for which
        ALTERNATIVE TEXTprovides an alias. May be omitted if given by
        context.
    :ivar text: Name of the entity.
    :ivar attribute_name: Name of text attribute for which this is the
        alternative tex. Must be an existing attribute name
    :ivar use_for_language: Name of language for which this is to be
        used.
    :ivar order: Order of name.
    """ 
    class Meta:
        name = "AlternativeText_VersionedChildStructure"
        
    data_managed_object_ref: Optional[VersionOfObjectRefStructure] = field(
        default=None,
        metadata={
            "name": "DataManagedObjectRef",
            "type": "Element",
            "namespace": "http://www.netex.org.uk/netex",
        }
    )       
    text: MultilingualString = field(
        metadata={
            "name": "Text",
            "type": "Element",
            "namespace": "http://www.netex.org.uk/netex",
            "required": True,
        }
    )
    attribute_name: Optional[str] = field(
        default=None,
        metadata={
            "name": "attributeName",
            "type": "Attribute",
        }
    )
    use_for_language: Optional[str] = field(
        default=None,
        metadata={
            "name": "useForLanguage",
            "type": "Attribute",
        }
    )
    order: Optional[int] = field(
        default=None,
        metadata={
            "type": "Attribute",
        }
    )

But the effect when looking at AlternativeText.dataclass_fields still include the fields outside the restriction inhereted via VersionedChildStructure:

I have been naively started to experiment if there was a clean way to clear the upstream inheritance, which was surprisingly simple. By just setting the already created field to None, dataclass_fields would ignore it.

@dataclass(unsafe_hash=True, kw_only=True)
class AlternativeTextVersionedChildStructure(VersionedChildStructure):
    """
    Type for ALTERNATIVE TEXT.

    :ivar data_managed_object_ref: Object for  attribute for which
        ALTERNATIVE TEXTprovides an alias. May be omitted if given by
        context.
    :ivar text: Name of the entity.
    :ivar attribute_name: Name of text attribute for which this is the
        alternative tex. Must be an existing attribute name
    :ivar use_for_language: Name of language for which this is to be
        used.
    :ivar order: Order of name.
    """
    class Meta:
        name = "AlternativeText_VersionedChildStructure"

    alternative_texts: None

    validity_conditions_or_valid_between: None

    extensions: None

    data_managed_object_ref: Optional[VersionOfObjectRefStructure] = field(
        default=None,
        metadata={
            "name": "DataManagedObjectRef",
            "type": "Element",
            "namespace": "http://www.netex.org.uk/netex",
        }
    )
    text: MultilingualString = field(
        metadata={
            "name": "Text",
            "type": "Element",
            "namespace": "http://www.netex.org.uk/netex",
            "required": True,
        }
    )
    attribute_name: Optional[str] = field(
        default=None,
        metadata={
            "name": "attributeName",
            "type": "Attribute",
        }
    )
    use_for_language: Optional[str] = field(
        default=None,
        metadata={
            "name": "useForLanguage",
            "type": "Attribute",
        }
    )
    order: Optional[int] = field(
        default=None,
        metadata={
            "type": "Attribute",
        }
    )

[skinkie]

Important comment:
NeTEx-CEN/NeTEx#531 (comment)

[tefra]

Hey @skinkie can you please provide a simple example of the behavior that needs to change? I am sorry netex is too complicated to follow.

[skinkie]

I think I already have an example schema somewhere. I'll try to post it tonight.

[skinkie]

Needed to be a bit more creative. As you can see from the (valid) XML example test3 is not allowed in the output. But the attribute version is correctly inherited. This has been described by O'Reilly. xsdata (current version) incorrently inherits test3, while it is not part of the restriction, thus should not be part of the final object.

ssp.xml.txt
ssp.xsd.txt

[tefra]

Our options here are

1. Flatten the extension (let's not do that)
2. Use ClassVar to override parent definition

from typing import ClassVar as RestrictedVar

@dataclass
class Parent:
    one: int
    two: int

@dataclass
class Child(Parent):
    two: RestrictedVar
    three: int

[skinkie]

RestrictedVar looks nice :-) Should I reuse is_prohibited, instead of my introduction of is_null?

[tefra]

the is_prohibited has a different application let's not mix those two

[tefra]

Hrm my suggestion doesn't work either mypy complaints with

error: Cannot override instance variable (previously declared on base class "Parent") with class variable

[tefra]

Our only options is to override the new field with init=Faslse