[英]Many-to-many multi-database join with Flask-SQLAlchemy
I'm trying to make this many-to-many join work with Flask-SQLAlchemy and two MySQL databases, and it's very close except it's using the wrong database for the join table. 我正在尝试使用Flask-SQLAlchemy和两个MySQL数据库进行多对多连接,除非它使用错误的数据库连接表,否则它非常接近。 Here's the basics...
这是基础......
I've got main_db
and vendor_db
. 我有
main_db
和vendor_db
。 The tables are setup as main_db.users
, main_db.user_products
(the relation table), and then vendor_db.products
. 这些表设置为
main_db.users
, main_db.user_products
(关系表),然后是vendor_db.products
。 Should be pretty clear how those are all connected. 应该很清楚这些是如何连接的。
in my app.py, I'm seting up the databases like this: 在我的app.py中,我正在设置这样的数据库:
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://user:pass@localhost/main_db'
app.config['SQLALCHEMY_BINDS'] = {
'vendor_db': 'mysql://user:pass@localhost/vendor_db'
}
Model definitions are set up like this: 模型定义设置如下:
from app import db
# Setup relationship
user_products_tbl = db.Table('user_products', db.metadata,
db.Column('user_id', db.Integer, db.ForeignKey('users.user_id')),
db.Column('product_id', db.Integer, db.ForeignKey('products.product_id'))
)
class User(db.Model):
__tablename__ = 'users'
id = db.Column('user_id', db.Integer, primary_key=True)
products = db.relationship("Product", secondary=user_products_tbl,
backref="users", lazy="dynamic")
class Product(db.Model):
__bind_key__ = 'vendor_db'
__tablename__ = 'products'
id = db.Column('product_id', db.Integer, primary_key=True)
name = db.Column(db.String(120))
The problem is that when I try to get a user's products it's trying to use vendor_db
for the join table instead of main_db
. 问题是,当我尝试获取用户的产品时,它试图使用
vendor_db
作为连接表而不是main_db
。 Any ideas how I can make it use main_db
instead? 有什么想法我可以使用
main_db
吗? I've tried setting up another bind to main_db
and setting info={'bind_key': 'main_db'}
on the relationship table definition, but no luck. 我已经尝试设置另一个绑定到
main_db
并在关系表定义上设置info={'bind_key': 'main_db'}
,但没有运气。 Thanks! 谢谢!
Turns out what I needed to do here was specify the schema in my user_products_tbl
table definition. 原来我需要做的是在
user_products_tbl
表定义中指定模式。 So, 所以,
user_products_tbl = db.Table('user_products', db.metadata,
db.Column('user_id', db.Integer, db.ForeignKey('users.user_id')),
db.Column('product_id', db.Integer, db.ForeignKey('products.product_id')),
schema='main_db'
)
Hope this helps someone else! 希望这有助于其他人!
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