Pydantic aliases

Aliased fields

pydantic library allows to set the alias for a field that is used during serialization/deserialization instead of the field name. pydantic-xml respects field aliases too:

Model

class Company(BaseXmlModel, tag='company'):
    title: str = attr(alias='trade-name')
    website: HttpUrl = element(alias='web-site')

Document

XML

<company trade-name="SpaceX">
    <web-site>https://www.spacex.com</web-site>
</company>

JSON

{
    "trade-name": "SpaceX",
    "web-site": "https://www.spacex.com"
}

Template models

pydantic aliases make it possible to declare so-called template models. The base model implements the data-validation and data-processing logic but the fields mapping is described in the inherited classes:

Model

class VehicleTemplate(BaseXmlModel):
    drivers: int = attr()
    title: str = attr()
    engine: str = element()


class Car(VehicleTemplate, tag='car'):
    model_config = pd.ConfigDict(
        alias_generator=lambda field: {'title': 'make', 'engine': 'motor'}.get(field, field),
    )


class Airplane(VehicleTemplate, tag='airplane'):
    model_config = pd.ConfigDict(
        alias_generator=lambda field: {'drivers': 'pilots', 'title': 'model'}.get(field, field),
    )


class Vehicles(BaseXmlModel, tag='vehicles'):
    items: List[Union[Car, Airplane]]

Document

XML

<vehicles>
    <car make="Ford Mustang" drivers="1">
        <motor>Coyote V8</motor>
    </car>
    <airplane model="Bombardier Global 7500" pilots="2">
        <engine>General Electric Passport</engine>
    </airplane>
    <car make="Audi A8" drivers="1">
        <motor>V8</motor>
    </car>
</vehicles>

JSON

{
    "items": [
        {
            "make": "Ford Mustang",
            "drivers": 1,
            "motor": "Coyote V8"
        },
        {
            "model": "Bombardier Global 7500",
            "pilots": 2,
            "engine": "General Electric Passport"
        },
        {
            "make": "Audi A8",
            "drivers": 1,
            "motor": "V8"
        }
    ]
}