orm2pydantic/src/orm2pydantic/sqla.py

83 lines
2.9 KiB
Python

from typing import Container, Type
from pydantic import create_model, BaseConfig, Field
from pydantic.fields import FieldInfo
from sqlalchemy.inspection import inspect
from sqlalchemy.orm import ColumnProperty, RelationshipProperty, Mapper
from sqlalchemy.orm.decl_api import DeclarativeMeta
from sqlalchemy.sql.schema import Column, ColumnDefault
from .utils import resolve_dotted_path
__all__ = [
'field_from_column',
'from_sqla'
]
FieldDef = tuple[type, FieldInfo]
_local_namespace = {}
class OrmConfig(BaseConfig):
orm_mode = True
def field_from_column(column: Column) -> FieldDef:
try:
field_type = column.type.impl.python_type
except AttributeError:
try:
field_type = column.type.python_type
except AttributeError:
raise AssertionError(f"Could not infer Python type for {column.key}")
default = ... if column.default is None and not column.nullable else column.default
if isinstance(default, ColumnDefault):
if default.is_scalar:
field_info = Field(default=default.arg)
else:
assert callable(default.arg)
dotted_path = default.arg.__module__ + '.' + default.arg.__name__
factory = resolve_dotted_path(dotted_path)
assert callable(factory)
field_info = Field(default_factory=factory)
else:
field_info = Field(default=default)
return field_type, field_info
def from_sqla(db_model: Type[DeclarativeMeta], incl_many_to_one: bool = True, incl_one_to_many: bool = False,
config: Type[BaseConfig] = OrmConfig, exclude: Container[str] = (),
add_fields: dict[str, FieldDef] = None):
assert isinstance(db_model, DeclarativeMeta)
assert not (incl_one_to_many and incl_many_to_one)
fields = {}
for attr in inspect(db_model).attrs:
if attr.key in exclude:
continue
if isinstance(attr, ColumnProperty):
assert len(attr.columns) == 1
column = attr.columns[0]
fields[attr.key] = field_from_column(column)
elif isinstance(attr, RelationshipProperty):
related = attr.mapper
assert isinstance(related, Mapper)
if incl_many_to_one and attr.direction.name == 'MANYTOONE':
fields[attr.key] = (related.class_.__name__, Field(default=None))
if incl_one_to_many and attr.direction.name == 'ONETOMANY':
fields[attr.key] = (list[related.class_.__name__], Field(default=None))
else:
raise AssertionError("Unknown attr type", attr)
if add_fields is not None:
fields |= add_fields
name = db_model.__name__
pydantic_model = create_model(name, __config__=config, **fields)
pydantic_model.__name__ = name
pydantic_model.update_forward_refs(**_local_namespace)
_local_namespace[name] = pydantic_model
return pydantic_model