OpenHome/venv/Lib/site-packages/flask_sqlalchemy/model.py
2021-07-21 21:33:05 +02:00

155 lines
4.9 KiB
Python

import re
import sqlalchemy as sa
from sqlalchemy import inspect
from sqlalchemy.ext.declarative import DeclarativeMeta, declared_attr
from sqlalchemy.schema import _get_table_key
from ._compat import to_str
def should_set_tablename(cls):
"""Determine whether ``__tablename__`` should be automatically generated
for a model.
* If no class in the MRO sets a name, one should be generated.
* If a declared attr is found, it should be used instead.
* If a name is found, it should be used if the class is a mixin, otherwise
one should be generated.
* Abstract models should not have one generated.
Later, :meth:`._BoundDeclarativeMeta.__table_cls__` will determine if the
model looks like single or joined-table inheritance. If no primary key is
found, the name will be unset.
"""
if (
cls.__dict__.get('__abstract__', False)
or not any(isinstance(b, DeclarativeMeta) for b in cls.__mro__[1:])
):
return False
for base in cls.__mro__:
if '__tablename__' not in base.__dict__:
continue
if isinstance(base.__dict__['__tablename__'], declared_attr):
return False
return not (
base is cls
or base.__dict__.get('__abstract__', False)
or not isinstance(base, DeclarativeMeta)
)
return True
camelcase_re = re.compile(r'([A-Z]+)(?=[a-z0-9])')
def camel_to_snake_case(name):
def _join(match):
word = match.group()
if len(word) > 1:
return ('_%s_%s' % (word[:-1], word[-1])).lower()
return '_' + word.lower()
return camelcase_re.sub(_join, name).lstrip('_')
class NameMetaMixin(type):
def __init__(cls, name, bases, d):
if should_set_tablename(cls):
cls.__tablename__ = camel_to_snake_case(cls.__name__)
super(NameMetaMixin, cls).__init__(name, bases, d)
# __table_cls__ has run at this point
# if no table was created, use the parent table
if (
'__tablename__' not in cls.__dict__
and '__table__' in cls.__dict__
and cls.__dict__['__table__'] is None
):
del cls.__table__
def __table_cls__(cls, *args, **kwargs):
"""This is called by SQLAlchemy during mapper setup. It determines the
final table object that the model will use.
If no primary key is found, that indicates single-table inheritance,
so no table will be created and ``__tablename__`` will be unset.
"""
# check if a table with this name already exists
# allows reflected tables to be applied to model by name
key = _get_table_key(args[0], kwargs.get('schema'))
if key in cls.metadata.tables:
return sa.Table(*args, **kwargs)
# if a primary key or constraint is found, create a table for
# joined-table inheritance
for arg in args:
if (
(isinstance(arg, sa.Column) and arg.primary_key)
or isinstance(arg, sa.PrimaryKeyConstraint)
):
return sa.Table(*args, **kwargs)
# if no base classes define a table, return one
# ensures the correct error shows up when missing a primary key
for base in cls.__mro__[1:-1]:
if '__table__' in base.__dict__:
break
else:
return sa.Table(*args, **kwargs)
# single-table inheritance, use the parent tablename
if '__tablename__' in cls.__dict__:
del cls.__tablename__
class BindMetaMixin(type):
def __init__(cls, name, bases, d):
bind_key = (
d.pop('__bind_key__', None)
or getattr(cls, '__bind_key__', None)
)
super(BindMetaMixin, cls).__init__(name, bases, d)
if bind_key is not None and getattr(cls, '__table__', None) is not None:
cls.__table__.info['bind_key'] = bind_key
class DefaultMeta(NameMetaMixin, BindMetaMixin, DeclarativeMeta):
pass
class Model(object):
"""Base class for SQLAlchemy declarative base model.
To define models, subclass :attr:`db.Model <SQLAlchemy.Model>`, not this
class. To customize ``db.Model``, subclass this and pass it as
``model_class`` to :class:`SQLAlchemy`.
"""
#: Query class used by :attr:`query`. Defaults to
# :class:`SQLAlchemy.Query`, which defaults to :class:`BaseQuery`.
query_class = None
#: Convenience property to query the database for instances of this model
# using the current session. Equivalent to ``db.session.query(Model)``
# unless :attr:`query_class` has been changed.
query = None
def __repr__(self):
identity = inspect(self).identity
if identity is None:
pk = "(transient {0})".format(id(self))
else:
pk = ', '.join(to_str(value) for value in identity)
return '<{0} {1}>'.format(type(self).__name__, pk)