在现有表中定义外键

Question

How would I define a foreign key between the tables in the example below? They have an identically named column, but I currently am unable to make joins.

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy import Table, Column, Integer, String

engine = create_engine('my connection details', echo=False)
Session = sessionmaker(bind=engine)
session = Session()
Base = declarative_base()

my_table = Table('my_table', 
    Base.metadata, 
    autoload=True, 
    autoload_with=engine, 
    schema='my_schema')

other_table = Table('other_table', 
    Base.metadata, 
    autoload=True, 
    autoload_with=engine, 
    schema='other_schema')

class MyClass(Base):
    __table__ = my_table

class OtherClass(Base):
    __table__ = other_table

Answer 1

I believe the ForeignKey s should be automatically reflected by sqlalchemy . Maybe the fact that you have two different schema s is the reason why it does not work in your case.

Anyways, according to Overriding Reflected Columns , you should be able to do something like:

my_table = Table('my_table', Base.metadata, 
    Column("my_id", Integer, ForeignKey("[other_schema].other_table.my_id")),
    autoload=True, autoload_with=engine, schema='my_schema')