Khi tôi cố gắng mã của bạn với sqlite
nó báo lỗi không cho nhưng khi nào, tôi đã cố gắng với MySQL
cơ sở dữ liệu tôi đã nhận lỗi
2012-03-29 10:43:15,330 INFO sqlalchemy.engine.base.Engine SELECT DATABASE()
2012-03-29 10:43:15,331 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,332 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'character_set%%'
2012-03-29 10:43:15,332 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,333 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'lower_case_table_names'
2012-03-29 10:43:15,333 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,334 INFO sqlalchemy.engine.base.Engine SHOW COLLATION
2012-03-29 10:43:15,334 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,337 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES LIKE 'sql_mode'
2012-03-29 10:43:15,338 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,339 INFO sqlalchemy.engine.base.Engine DESCRIBE `user_tasks`
2012-03-29 10:43:15,339 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,355 INFO sqlalchemy.engine.base.Engine DESCRIBE `users`
2012-03-29 10:43:15,355 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,356 INFO sqlalchemy.engine.base.Engine DESCRIBE `tasks`
2012-03-29 10:43:15,356 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,357 INFO sqlalchemy.engine.base.Engine
DROP TABLE user_tasks
2012-03-29 10:43:15,357 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,439 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:15,440 INFO sqlalchemy.engine.base.Engine
DROP TABLE users
2012-03-29 10:43:15,440 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,573 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:15,573 INFO sqlalchemy.engine.base.Engine
DROP TABLE tasks
2012-03-29 10:43:15,573 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,623 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:15,624 INFO sqlalchemy.engine.base.Engine DESCRIBE `tasks`
2012-03-29 10:43:15,624 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,632 INFO sqlalchemy.engine.base.Engine ROLLBACK
2012-03-29 10:43:15,633 INFO sqlalchemy.engine.base.Engine DESCRIBE `users`
2012-03-29 10:43:15,633 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,634 INFO sqlalchemy.engine.base.Engine ROLLBACK
2012-03-29 10:43:15,634 INFO sqlalchemy.engine.base.Engine DESCRIBE `user_tasks`
2012-03-29 10:43:15,634 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,635 INFO sqlalchemy.engine.base.Engine ROLLBACK
2012-03-29 10:43:15,635 INFO sqlalchemy.engine.base.Engine
CREATE TABLE tasks (
task_id INTEGER NOT NULL AUTO_INCREMENT,
description TEXT,
PRIMARY KEY (task_id)
)
2012-03-29 10:43:15,635 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,732 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:15,733 INFO sqlalchemy.engine.base.Engine
CREATE TABLE users (
user_id INTEGER NOT NULL AUTO_INCREMENT,
email VARCHAR(20),
PRIMARY KEY (user_id),
UNIQUE (email)
)
2012-03-29 10:43:15,733 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,841 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:15,842 INFO sqlalchemy.engine.base.Engine
CREATE TABLE user_tasks (
user_id INTEGER,
task_id INTEGER,
FOREIGN KEY(user_id) REFERENCES users (user_id),
FOREIGN KEY(task_id) REFERENCES tasks (task_id)
)
2012-03-29 10:43:15,842 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:15,959 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:15,964 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2012-03-29 10:43:15,965 INFO sqlalchemy.engine.base.Engine INSERT INTO users (email) VALUES (%s)
2012-03-29 10:43:15,965 INFO sqlalchemy.engine.base.Engine ('user',)
2012-03-29 10:43:15,966 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:16,010 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2012-03-29 10:43:16,010 INFO sqlalchemy.engine.base.Engine SELECT users.user_id AS users_user_id, users.email AS users_email
FROM users
2012-03-29 10:43:16,011 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:16,013 INFO sqlalchemy.engine.base.Engine INSERT INTO tasks (description) VALUES (%s)
2012-03-29 10:43:16,014 INFO sqlalchemy.engine.base.Engine ('user_one task',)
2012-03-29 10:43:16,015 INFO sqlalchemy.engine.base.Engine INSERT INTO user_tasks (user_id, task_id) VALUES (%s, %s)
2012-03-29 10:43:16,016 INFO sqlalchemy.engine.base.Engine (1L, 1L)
2012-03-29 10:43:16,016 INFO sqlalchemy.engine.base.Engine COMMIT
2012-03-29 10:43:16,085 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2012-03-29 10:43:16,086 INFO sqlalchemy.engine.base.Engine SELECT tasks.task_id AS tasks_task_id, tasks.description AS tasks_description
FROM tasks
2012-03-29 10:43:16,086 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:16,087 INFO sqlalchemy.engine.base.Engine SELECT user_tasks.user_id AS user_tasks_user_id, user_tasks.task_id AS user_tasks_task_id
FROM user_tasks
2012-03-29 10:43:16,088 INFO sqlalchemy.engine.base.Engine()
2012-03-29 10:43:16,089 INFO sqlalchemy.engine.base.Engine SELECT user_tasks.user_id AS user_tasks_user_id, user_tasks.task_id AS user_tasks_task_id
FROM user_tasks
2012-03-29 10:43:16,089 INFO sqlalchemy.engine.base.Engine()
[(1L, 1L)]
2012-03-29 10:43:16,091 INFO sqlalchemy.engine.base.Engine DELETE FROM tasks
2012-03-29 10:43:16,091 INFO sqlalchemy.engine.base.Engine()
Traceback (most recent call last):
File "/tmp/test2.py", line 46, in <module>
s.query(Task).delete()
File "/home/npatel/.local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2283, in delete
result = session.execute(delete_stmt, params=self._params)
File "/home/npatel/.local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 762, in execute
clause, params or {})
File "/home/npatel/.local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1399, in execute
params)
File "/home/npatel/.local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1532, in _execute_clauseelement
compiled_sql, distilled_params
File "/home/npatel/.local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1640, in _execute_context
context)
File "/home/npatel/.local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1633, in _execute_context
context)
File "/home/npatel/.local/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 325, in do_execute
cursor.execute(statement, parameters)
File "/usr/lib64/python2.7/site-packages/MySQLdb/cursors.py", line 174, in execute
self.errorhandler(self, exc, value)
File "/usr/lib64/python2.7/site-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
raise errorclass, errorvalue
sqlalchemy.exc.IntegrityError: (IntegrityError) (1451, 'Cannot delete or update a parent row: a foreign key constraint fails (`test1`.`user_tasks`, CONSTRAINT `user_tasks_ibfk_2` FOREIGN KEY (`task_id`) REFERENCES `tasks` (`task_id`))') 'DELETE FROM tasks'()
Vì vậy, sau đó tôi đến để biết rằng sqlite
không duy trì ràng buộc khoá ngoại . Bây giờ tôi thay đổi mã của bạn và kiểm tra đầu ra.
from sqlalchemy import create_engine, Column, Integer, Text, Table, ForeignKey, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import Session, relationship
Model = declarative_base()
class User(Model):
__tablename__ = 'users'
id = Column('user_id', Integer, primary_key=True)
email = Column('email', String(length=20), unique=True)
def __init__(self, email):
self.email = email
user_tasks = Table('user_tasks', Model.metadata,
Column('user_id', Integer, ForeignKey('users.user_id')),
Column('task_id', Integer, ForeignKey('tasks.task_id')))
class Task(Model):
__tablename__ = 'tasks'
id = Column('task_id', Integer, primary_key=True)
description = Column('description', Text)
assigned_to = relationship('User', secondary=user_tasks, backref='tasks')
def __init__(self, description):
self.description = description
if __name__ == '__main__':
engine = create_engine('mysql://test:[email protected]/test', echo=True)
Model.metadata.drop_all(engine)
Model.metadata.create_all(engine)
s = Session(engine)
the_user = User('user')
s.add(the_user)
s.commit()
assert s.query(User).all() == [the_user]
user_task = Task('user_one task')
user_task.assigned_to.append(the_user)
s.add(user_task)
s.commit()
assert s.query(Task).all() == [user_task]
assert s.query(user_tasks).all() == [(1, 1)]
the_user.tasks = []
s.query(Task).delete()
s.commit()
assert s.query(Task).all() == []
assert s.query(User).all() == [the_user]
assert s.query(user_tasks).all() == [(1,1)] # I was expecting [] .
tôi tin rằng phiên bản của tôi về sqlite3 (? 3.7.3 tôi nghĩ) hỗ trợ bảng nước ngoài? Tôi có phải bật tính năng này một cách cụ thể không? Hoặc là có cách nào khác để làm cho nó hoạt động với SQLite3? – Buttons840
Tính năng của SQLite3 được mô tả tại http://sqlite.org/foreignkeys.html. Nếu bạn muốn sử dụng điều đó, bạn sẽ sử dụng trình xử lý sự kiện trong SQLAlchemy để đặt PRAGMA mỗi khi một kết nối mới được tạo (sự kiện "kết nối"). Một cách khác để làm điều này là sử dụng Session.delete() trên mỗi đối tượng Task trực tiếp, SQLA sẽ đi qua nỗ lực phụ để duy trì mối quan hệ "assigned_to". – zzzeek
Liên kết http://docs.sqlalchemy.org/en/latest/core/schema.html#on-update-and-on-delete hợp lệ, nhưng không tìm thấy liên kết đến 'on-update-and- on-delete'. Nó dường như bị mất, cũng như trong phiên bản 0.9 và 1.0. – fedorqui