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[英]Using a different schema for the same declarative Base in sqlalchemy
[英]SqlAlchemy ForeignKey on different schema not found
所以在 2 個不同的模式上有 2 個不同的模型。 一個與另一個有外鍵關系。 我運行BaseOne.metadata.create_all(engine)
然后BaseTwo.metadata.create_all(engine)
我得到BaseTwo.metadata.create_all(engine)
sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column...
BaseOne = declarative_base(metadata=MetaData(schema="a"))
BaseTwo = declarative_base(metadata=MetaData(schema="b"))
class Parent(BaseOne):
__tablename__ = "parent"
parent_id = Column(Integer, primary_key=True)
other_col = Column(String(20))
children = relationship("Child", backref="parent")
class Child(BaseTwo):
__tablename__ = "child"
child_id = Column(Integer, primary_key=True)
parent_id = Column(Integer, ForeignKey("a.parent.parent_id"), nullable=False)
# Where I'm creating them
BaseOne.metadata.create_all(engine)
BaseTwo.metadata.create_all(engine)
應該注意,我還嘗試通過__table_args__
明確說明架構。 此外,我已連接到我的 postgres 實例並驗證了父表是否存在於目標列中。
看來問題是由於我使用了多個MetaData
對象。 似乎他們無法見面。 簡化為單個聲明性基礎並使用__table_args__
來聲明模式似乎有效。 如果有人知道如何聲明多個元數據對象並且仍然能夠使用.create_all
隨時發布。
這可以通過使用 Alembic 來管理表創建來解決。 確保所有鹼基都包含在target_metadata
列表中,例如:
# pylint: skip-file
import os
from logging.config import fileConfig
from alembic import context
from sqlalchemy import engine_from_config
from sqlalchemy import pool
import unimatrix.ext.octet.orm
import gpo.infra.orm
# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name)
# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
target_metadata = [
unimatrix.ext.octet.orm.metadata,
gpo.infra.orm.Relation.metadata
]
# Configure SQLAlchemy to use the DB_URI environment variable.
config.set_main_option("sqlalchemy.url", os.environ["DB_URI"])
def run_migrations_offline():
"""Run migrations in 'offline' mode.
This configures the context with just a URL
and not an Engine, though an Engine is acceptable
here as well. By skipping the Engine creation
we don't even need a DBAPI to be available.
Calls to context.execute() here emit the given string to the
script output.
"""
url = config.get_main_option("sqlalchemy.url")
context.configure(
url=url,
target_metadata=target_metadata,
literal_binds=True,
dialect_opts={"paramstyle": "named"},
)
with context.begin_transaction():
context.run_migrations()
def run_migrations_online():
"""Run migrations in 'online' mode.
In this scenario we need to create an Engine
and associate a connection with the context.
"""
connectable = engine_from_config(
config.get_section(config.config_ini_section),
prefix="sqlalchemy.",
poolclass=pool.NullPool,
)
with connectable.connect() as connection:
context.configure(
connection=connection, target_metadata=target_metadata
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
``
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