PydanticModel class

[dantownsend]

Currently we have good Pydantic support, via the create_pydantic_model function (see docs). For example:

BandModel = create_pydantic_model(table=Band, exclude_columns=(Band.popularity,), model_name='BandModel')

We could potentially add a PydanticModel class, which performs something similar (it will likely use create_pydantic_model under the hood):

# The class will accept most of the arguments that `create_pydantic_model` does:
class BandModel(PydanticModel, table=Band, exclude_columns=(Band.popularity,)):
    # We can define additional fields:
    some_extra_field: int

It would require some metaclass magic to make this work.

The advantages over create_pydantic_model are:

It's easier to add additional fields to the model

With create_pydantic_model:

BandModel = create_pydantic_model(table=Band)
class BandModelExtended(BandModel):
    some_extra_field: str

With PydanticModel:

class BandModelExtended(PydanticModel, table=Band):
    some_extra_field: str

Less likely a name clash will occur

With create_pydantic_model, if it's used multiple times on the same table, it's important to provide the model_name argument, to prevent issues with FastAPI:

BandModel = create_pydantic_model(table=Band, model_name='BandModel')
BandModelOptional = create_pydantic_model(table=Band, optional=True, model_name='BandModelOptional')

With PydanticModel, this problem is avoided, as the model name is automatically just the class name.

class BandModel(PydanticModel, table=Band):
    pass

class BandModelOptional(PydanticModel, table=Band, optional=True):
    pass

Update 24/3/2022

If building a new API around Pydantic model creation, these are the other things I'd change from the current create_pydantic_model implementation:

• Support choices properly (see Choices enum not reflected in Swagger #467)
• Remove the include_default_columns option, as it's redundant now include_columns and exclude_columns exist.