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[英]ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails That I can't fix
[英]How to fix 'Cannot add or update a child row: a foreign key constraint fails' when creating new model instance in peewee
我想在表中添加一个新的模型实例,但它总是显示“无法添加或更新子行:外键约束失败”。
我已经检查过userTd是否有UserId。 这是userTable的内容:
{“ID”:1,“UserId”:“001201400047”,“UserName”:“用户A”,“UserPass”:“admin”,“UserStatus”:“admin”},
{“ID”:2,“UserId”:“100100010000”,“UserName”:“User B”,“UserPass”:“user”,“UserStatus”:“student”}
from peewee import *
from datetime import datetime
database = MySQLDatabase('AAS', **{'passwd': 'admin', 'charset': 'utf8', 'user': 'yusfa', 'use_unicode': True})
class UnknownField(object):
def __init__(self, *_, **__): pass
class BaseModel(Model):
class Meta:
database = database
class Classtable(BaseModel):
classid = CharField(column_name='ClassId', primary_key=True)
lecturerid = ForeignKeyField(column_name='LecturerId', model=Lecturertable)
roomid = ForeignKeyField(column_name='RoomId', model=Roomtable)
subjectid = ForeignKeyField(column_name='SubjectId', model=Subjecttable)
class Meta:
table_name = 'classTable'
class Usertable(BaseModel):
id = AutoField(column_name='ID')
userid = CharField(column_name='UserId', unique=True)
username = CharField(column_name='UserName', null=True)
userpass = CharField(column_name='UserPass', null=True)
userstatus = CharField(column_name='UserStatus', null=True)
class Meta:
table_name = 'userTable'
class Attendancetable(BaseModel):
classid = ForeignKeyField(column_name='ClassId', model=Classtable, null=True)
date = DateTimeField(column_name='Date', null=True)
id = AutoField(column_name='ID')
userid = ForeignKeyField(column_name='UserId', model=Usertable, null=True)
class Meta:
table_name = 'attendanceTable'
database.connect()
times = ' 7:30:00'
x = 001201400047
x_attended = Attendancetable.create(classid = 'IT_20141', date = str(datetime.now()).split(' ')[0] + times, userid = str(x))
x_attended.save()
database.close()
我预计会有里面Attendancetable一个新的模型实例,但实际产量peewee.IntegrityError:(1452,“不能添加或更新子行,外键约束失败( AAS
。 attendanceTable
,约束fk_attendanceTable_1
外键( UserId
)参考userTable
( userid
))')。
编辑 :我试图将x值更改为字符串,问题保持不变。 以下是完整的错误消息:
Traceback (most recent call last):
File "test6.py", line 93, in <module>
x_attended = Attendancetable.create(classid = 'IT_20141', date = str(datetime.now()).split(' ')[0] + times, userid = x)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 5580, in create
inst.save(force_insert=True)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 5727, in save
pk_from_cursor = self.insert(**field_dict).execute()
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 1622, in inner
return method(self, database, *args, **kwargs)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 1693, in execute
return self._execute(database)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2355, in _execute
return super(Insert, self)._execute(database)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2118, in _execute
cursor = database.execute(self)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2724, in execute
return self.execute_sql(sql, params, commit=commit)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2718, in execute_sql
self.commit()
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2509, in __exit__
reraise(new_type, new_type(*exc_args), traceback)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2711, in execute_sql
cursor.execute(sql, params or ())
File "/usr/lib/python2.7/dist-packages/MySQLdb/cursors.py", line 250, in execute
self.errorhandler(self, exc, value)
File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 50, in defaulterrorhandler
raise errorvalue
peewee.IntegrityError: (1452, 'Cannot add or update a child row: a foreign key constraint fails (`AAS`.`attendanceTable`, CONSTRAINT `fk_attendanceTable_1` FOREIGN KEY (`UserId`) REFERENCES `userTable` (`userid`))')
Traceback (most recent call last):
File "test6.py", line 93, in <module>
x_attended = Attendancetable.create(classid = 'IT_20141', date = str(datetime.now()).split(' ')[0] + times, userid = x)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 5580, in create
inst.save(force_insert=True)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 5727, in save
pk_from_cursor = self.insert(**field_dict).execute()
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 1622, in inner
return method(self, database, *args, **kwargs)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 1693, in execute
return self._execute(database)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2355, in _execute
return super(Insert, self)._execute(database)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2118, in _execute
cursor = database.execute(self)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2724, in execute
return self.execute_sql(sql, params, commit=commit)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2718, in execute_sql
self.commit()
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2509, in __exit__
reraise(new_type, new_type(*exc_args), traceback)
File "/home/user/.local/lib/python2.7/site-packages/peewee.py", line 2711, in execute_sql
cursor.execute(sql, params or ())
File "/usr/lib/python2.7/dist-packages/MySQLdb/cursors.py", line 250, in execute
self.errorhandler(self, exc, value)
File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 50, in defaulterrorhandler
raise errorvalue
peewee.IntegrityError: (1452, 'Cannot add or update a child row: a foreign key constraint fails (`AAS`.`attendanceTable`, CONSTRAINT `fk_attendanceTable_1` FOREIGN KEY (`UserId`) REFERENCES `userTable` (`userid`))')
当您将x
转换为下一行的字符串时, x
的前导零不会被保留。 行插入失败,因为"1201400047"
不在["001201400047", "100100010000"]
str(x).zfill(USER_ID_WIDTH)
可能是一个解决方案
模型类表示fk来自Attendancetable.userid - > Usertable.id
db约束表示外键来自Attendancetable.userid - > Usertable.userid
可能需要修复模型定义,以便FK指向右列:
class Attendancetable(BaseModel):
classid = ForeignKeyField(column_name='ClassId', model=Classtable, null=True)
date = DateTimeField(column_name='Date', null=True)
id = AutoField(column_name='ID')
userid = ForeignKeyField(column_name='UserId', field='userid', model=Usertable, null=True)
看起来你预先存在的架构也许有点乱。 所以你可能需要稍微清理一下。
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