提交会话之前获取插入的密钥 [英] Get inserted key before commit session
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问题描述
id = db.Column(db.Integer,primary_key = True)
$ b $ class Child(db .Model):
id = db.Column(db.Integer,primary_key = True)
parent_id = db.Column(db.Integer,db.ForeignKey('parent.id'))
parent = Parent()
db.session.add(parent)
$ b $ child = Child()
child.parent_id = parent.id
db.session.add(child)
db.session.commit()
我想将 INSERT 插入会话中的父
和子
表中, parent_id
必须包含在子
表中。在创建子元素
对象的那一刻, parent.id
为 None >
如何才能达到这个目标?
=http://docs.sqlalchemy.org/en/latest/orm/session_api.html?highlight=flush#sqlalchemy.orm.session.Session.flush =noreferrer> flush()刷新对数据库的更改,从而更新主键字段:$ $ $ $ $ $ $ $ $ $ $ $ $ $ db $。 session.add(parent)
db.session.flush()
在flush()后打印parent.id,父对象将被自动赋值为
#其ID域的键
child = Child()
child.parent_id = parent.id
db.session.add(child)
class Parent(db.Model):
id = db.Column(db.Integer, primary_key=True)
class Child(db.Model):
id = db.Column(db.Integer, primary_key=True)
parent_id = db.Column(db.Integer, db.ForeignKey('parent.id'))
parent = Parent()
db.session.add(parent)
child = Child()
child.parent_id = parent.id
db.session.add(child)
db.session.commit()
I want to INSERT into both parent
and child
tables inside a session considering that the parent_id
must be included in the child
table. In the moment I create the child
object, parent.id
is None.
How can I achieve that?
解决方案
You could use flush() to flush changes to the database and thus have your primary-key field updated:
parent = Parent()
db.session.add(parent)
db.session.flush()
print parent.id # after flush(), parent object would be automatically
# assigned with a unique primary key to its id field
child = Child()
child.parent_id = parent.id
db.session.add(child)
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