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我正在尝试创建一个使用 UUID_SHORT() 作为主键的表。我有一个触发器,可以在您执行插入操作时插入一个值。我无法让 sqlalchemy 将列识别为 primary_key
而不会提示不提供默认值。如果我确实包含默认值,即使声明了 server_default=FetchedValue()
,它也会在刷新后使用该默认值。我似乎能让事情正常工作的唯一方法是如果该列不是主键。
我正在使用 Pyramid、SQLAlchemy ORM 和 MySQL。
这是模型对象:
Base = declarative_base()
class Patient(Base):
__tablename__ = 'patient'
patient_id = Column(BigInteger(unsigned=True), server_default=FetchedValue(), primary_key=True, autoincrement=False)
details = Column(Binary(10000))
在 initializedb.py 中我有:
with transaction.manager:
patient1 = Patient(details = None)
DBSession.add(patient1)
DBSession.flush()
print(patient1.patient_id)
运行 ../bin/initialize_mainserver_db development.ini
给我以下错误:
2012-11-01 20:17:22,168 INFO [sqlalchemy.engine.base.Engine][MainThread] BEGIN (implicit)
2012-11-01 20:17:22,169 INFO [sqlalchemy.engine.base.Engine][MainThread] INSERT INTO patient (details) VALUES (%(details)s)
2012-11-01 20:17:22,169 INFO [sqlalchemy.engine.base.Engine][MainThread] {'details': None}
2012-11-01 20:17:22,170 INFO [sqlalchemy.engine.base.Engine][MainThread] ROLLBACK
Traceback (most recent call last):
File "/sites/metrics_dev/lib/python3.3/site-packages/sqlalchemy/engine/base.py", line 1691, in _execute_context
context)
File "/sites/metrics_dev/lib/python3.3/site-packages/sqlalchemy/engine/default.py", line 333, in do_execute
cursor.execute(statement, parameters)
File "/sites/metrics_dev/lib/python3.3/site-packages/mysql/connector/cursor.py", line 418, in execute
self._handle_result(self._connection.cmd_query(stmt))
File "/sites/metrics_dev/lib/python3.3/site-packages/mysql/connector/cursor.py", line 345, in _handle_result
self._handle_noresultset(result)
File "/sites/metrics_dev/lib/python3.3/site-packages/mysql/connector/cursor.py", line 321, in _handle_noresultset
self._warnings = self._fetch_warnings()
File "/sites/metrics_dev/lib/python3.3/site-packages/mysql/connector/cursor.py", line 608, in _fetch_warnings
raise errors.get_mysql_exception(res[0][1],res[0][2])
mysql.connector.errors.DatabaseError: 1364: Field 'patient_id' doesn't have a default value
使用 mysql 客户端运行手动插入会导致一切正常,因此问题似乎出在 SQLAlchemy 上。
mysql> insert into patient(details) values (null);
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> select * from patient;
+-------------------+---------+
| patient_id | details |
+-------------------+---------+
| 94732327996882980 | NULL |
+-------------------+---------+
1 row in set (0.00 sec)
mysql> show triggers;
+-----------------------+--------+---------+-------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+
| Trigger | Event | Table | Statement | Timing | Created | sql_mode | Definer | character_set_client | collation_connection | Database Collation |
+-----------------------+--------+---------+-------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+
| before_insert_patient | INSERT | patient | SET new.`patient_id` = UUID_SHORT() | BEFORE | NULL | | root@localhost | utf8 | utf8_general_ci | latin1_swedish_ci |
+-----------------------+--------+---------+-------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+
1 row in set (0.00 sec)
最佳答案
这是我作为解决方法所做的...
DBSession.execute(
"""CREATE TRIGGER before_insert_patient BEFORE INSERT ON `patient`
FOR EACH ROW BEGIN
IF (NEW.patient_id IS NULL OR NEW.patient_id = 0) THEN
SET NEW.patient_id = UUID_SHORT();
END IF;
END""")
在患者类中:
patient_id = Column(BigInteger(unsigned=True), default=text("uuid_short()"), primary_key=True, autoincrement=False, server_default="0")
因此,只有当有人直接访问数据库而不是通过 python 代码时,触发器才会执行某些操作。希望没有人这样做 patient1 = Patient(patient_id=0, details = None)
因为 SQLAlchemy 将使用“0”值而不是触发器产生的值
关于mysql - sqlalchemy FetchedValue 和 primary_key,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13184916/
我正在尝试创建一个使用 UUID_SHORT() 作为主键的表。我有一个触发器,可以在您执行插入操作时插入一个值。我无法让 sqlalchemy 将列识别为 primary_key 而不会提示不提供默
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