Files
ormar/ormar/models/metaclass.py

200 lines
6.3 KiB
Python

from typing import Any, Dict, List, Optional, TYPE_CHECKING, Tuple, Type, Union
import databases
import pydantic
import sqlalchemy
from pydantic import BaseConfig
from pydantic.fields import FieldInfo
from ormar import ForeignKey, ModelDefinitionError # noqa I100
from ormar.fields import BaseField
from ormar.fields.foreign_key import ForeignKeyField
from ormar.queryset import QuerySet
from ormar.relations import AliasManager
if TYPE_CHECKING: # pragma no cover
from ormar import Model
alias_manager = AliasManager()
class ModelMeta:
tablename: str
table: sqlalchemy.Table
metadata: sqlalchemy.MetaData
database: databases.Database
columns: List[sqlalchemy.Column]
pkname: str
model_fields: Dict[str, Union[BaseField, ForeignKey]]
alias_manager: AliasManager
def register_relation_on_build(table_name: str, field: ForeignKey) -> None:
alias_manager.add_relation_type(field, table_name)
def reverse_field_not_already_registered(
child: Type["Model"], child_model_name: str, parent_model: Type["Model"]
) -> bool:
return (
child_model_name not in parent_model.__fields__
and child.get_name() not in parent_model.__fields__
)
def expand_reverse_relationships(model: Type["Model"]) -> None:
for model_field in model.Meta.model_fields.values():
if issubclass(model_field, ForeignKeyField):
child_model_name = model_field.related_name or model.get_name() + "s"
parent_model = model_field.to
child = model
if reverse_field_not_already_registered(
child, child_model_name, parent_model
):
register_reverse_model_fields(parent_model, child, child_model_name)
def register_reverse_model_fields(
model: Type["Model"], child: Type["Model"], child_model_name: str
) -> None:
model.Meta.model_fields[child_model_name] = ForeignKey(
child, name=child_model_name, virtual=True
)
def check_pk_column_validity(
field_name: str, field: BaseField, pkname: str
) -> Optional[str]:
if pkname is not None:
raise ModelDefinitionError("Only one primary key column is allowed.")
if field.pydantic_only:
raise ModelDefinitionError("Primary key column cannot be pydantic only")
return field_name
def sqlalchemy_columns_from_model_fields(
model_fields: Dict, table_name: str
) -> Tuple[Optional[str], List[sqlalchemy.Column]]:
columns = []
pkname = None
for field_name, field in model_fields.items():
if field.primary_key:
pkname = check_pk_column_validity(field_name, field, pkname)
if not field.pydantic_only:
columns.append(field.get_column(field_name))
if issubclass(field, ForeignKeyField):
register_relation_on_build(table_name, field)
return pkname, columns
def populate_default_pydantic_field_value(
type_: Type[BaseField], field: str, attrs: dict
) -> dict:
def_value = type_.default_value()
curr_def_value = attrs.get(field, "NONE")
if curr_def_value == "NONE" and isinstance(def_value, FieldInfo):
attrs[field] = def_value
elif curr_def_value == "NONE" and type_.nullable:
attrs[field] = FieldInfo(default=None)
return attrs
def populate_pydantic_default_values(attrs: Dict) -> Dict:
for field, type_ in attrs["__annotations__"].items():
if issubclass(type_, BaseField):
if type_.name is None:
type_.name = field
attrs = populate_default_pydantic_field_value(type_, field, attrs)
return attrs
def extract_annotations_and_module(
attrs: dict, new_model: "ModelMetaclass", bases: Tuple
) -> dict:
annotations = attrs.get("__annotations__") or new_model.__annotations__
attrs["__annotations__"] = annotations
attrs = populate_pydantic_default_values(attrs)
attrs["__module__"] = attrs["__module__"] or bases[0].__module__
attrs["__annotations__"] = attrs["__annotations__"] or bases[0].__annotations__
return attrs
def populate_meta_orm_model_fields(
attrs: dict, new_model: Type["Model"]
) -> Type["Model"]:
model_fields = {
field_name: field
for field_name, field in attrs["__annotations__"].items()
if issubclass(field, BaseField)
}
new_model.Meta.model_fields = model_fields
return new_model
def populate_meta_tablename_columns_and_pk(
name: str, new_model: Type["Model"]
) -> Type["Model"]:
tablename = name.lower() + "s"
new_model.Meta.tablename = new_model.Meta.tablename or tablename
if hasattr(new_model.Meta, "columns"):
columns = new_model.Meta.table.columns
pkname = new_model.Meta.pkname
else:
pkname, columns = sqlalchemy_columns_from_model_fields(
new_model.Meta.model_fields, new_model.Meta.tablename
)
new_model.Meta.columns = columns
new_model.Meta.pkname = pkname
if not new_model.Meta.pkname:
raise ModelDefinitionError("Table has to have a primary key.")
return new_model
def populate_meta_sqlalchemy_table_if_required(
new_model: Type["Model"],
) -> Type["Model"]:
if not hasattr(new_model.Meta, "table"):
new_model.Meta.table = sqlalchemy.Table(
new_model.Meta.tablename, new_model.Meta.metadata, *new_model.Meta.columns
)
return new_model
def get_pydantic_base_orm_config() -> Type[BaseConfig]:
class Config(BaseConfig):
orm_mode = True
arbitrary_types_allowed = True
return Config
class ModelMetaclass(pydantic.main.ModelMetaclass):
def __new__(mcs: type, name: str, bases: Any, attrs: dict) -> type:
attrs["Config"] = get_pydantic_base_orm_config()
new_model = super().__new__( # type: ignore
mcs, name, bases, attrs
)
if hasattr(new_model, "Meta"):
attrs = extract_annotations_and_module(attrs, new_model, bases)
new_model = populate_meta_orm_model_fields(attrs, new_model)
new_model = populate_meta_tablename_columns_and_pk(name, new_model)
new_model = populate_meta_sqlalchemy_table_if_required(new_model)
expand_reverse_relationships(new_model)
new_model = super().__new__( # type: ignore
mcs, name, bases, attrs
)
new_model.Meta.alias_manager = alias_manager
new_model.objects = QuerySet(new_model)
return new_model