Files
ormar/ormar/relations.py
2020-08-23 12:54:58 +02:00

106 lines
3.8 KiB
Python

import pprint
import string
import uuid
from random import choices
from typing import List, TYPE_CHECKING, Union
from weakref import proxy
from ormar.fields.foreign_key import ForeignKeyField
if TYPE_CHECKING: # pragma no cover
from ormar.models import FakePydantic, Model
def get_table_alias() -> str:
return "".join(choices(string.ascii_uppercase, k=2)) + uuid.uuid4().hex[:4]
class RelationshipManager:
def __init__(self) -> None:
self._relations = dict()
self._aliases = dict()
def add_relation_type(
self,
relations_key: str,
reverse_key: str,
field: ForeignKeyField,
table_name: str,
) -> None:
if relations_key not in self._relations:
self._relations[relations_key] = {"type": "primary"}
self._aliases[f"{table_name}_{field.to.Meta.tablename}"] = get_table_alias()
if reverse_key not in self._relations:
self._relations[reverse_key] = {"type": "reverse"}
self._aliases[f"{field.to.Meta.tablename}_{table_name}"] = get_table_alias()
def deregister(self, model: "FakePydantic") -> None:
for rel_type in self._relations.keys():
if model.get_name() in rel_type.lower():
if model._orm_id in self._relations[rel_type]:
del self._relations[rel_type][model._orm_id]
def add_relation(
self,
parent: "FakePydantic",
child: "FakePydantic",
child_model_name: str,
virtual: bool = False,
) -> None:
parent_id, child_id = parent._orm_id, child._orm_id
parent_name = parent.get_name(title=True)
child_name = (
child_model_name
if child.get_name() != child_model_name
else child.get_name() + "s"
)
if virtual:
child_name, parent_name = parent_name, child.get_name()
child_id, parent_id = parent_id, child_id
child, parent = parent, proxy(child)
child_name = child_name.lower() + "s"
else:
child = proxy(child)
parent_relation_name = parent_name.title() + "_" + child_name
parents_list = self._relations[parent_relation_name].setdefault(parent_id, [])
self.append_related_model(parents_list, child)
child_relation_name = child.get_name(title=True) + "_" + parent_name.lower()
children_list = self._relations[child_relation_name].setdefault(child_id, [])
self.append_related_model(children_list, parent)
@staticmethod
def append_related_model(relations_list: List["Model"], model: "Model") -> None:
for relation_child in relations_list:
try:
if relation_child.__same__(model):
return
except ReferenceError:
continue
relations_list.append(model)
def contains(self, relations_key: str, instance: "FakePydantic") -> bool:
if relations_key in self._relations:
return instance._orm_id in self._relations[relations_key]
return False
def get(
self, relations_key: str, instance: "FakePydantic"
) -> Union["Model", List["Model"]]:
if relations_key in self._relations:
if instance._orm_id in self._relations[relations_key]:
if self._relations[relations_key]["type"] == "primary":
return self._relations[relations_key][instance._orm_id][0]
return self._relations[relations_key][instance._orm_id]
def resolve_relation_join(self, from_table: str, to_table: str) -> str:
return self._aliases.get(f"{from_table}_{to_table}", "")
def __str__(self) -> str: # pragma no cover
return pprint.pformat(self._relations, indent=4, width=1)
def __repr__(self) -> str: # pragma no cover
return self.__str__()