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I have a Salad model:
class Salad(models.Model):
some_field = models.ForeignKey(Profile, on_delete=models.CASCADE, null=True)
No matter how I call the class, the single field, what models I put instead of Profile, or whichever on_delete option I choose. I systematically get the error:
django.db.utils.IntegrityError: (1215, 'Cannot add foreign key constraint')
The error log:
Traceback (most recent call last):
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
Applying playerdata.0053_auto_20180724_1943... return self.cursor.execute(sql, params)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\mysql\base.py", line 71, in execute
return self.cursor.execute(query, args)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 250, in execute
self.errorhandler(self, exc, value)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 50, in defaulterrorhandler
raise errorvalue
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 247, in execute
res = self._query(query)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 411, in _query
rowcount = self._do_query(q)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 374, in _do_query
db.query(q)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 292, in query
_mysql.connection.query(self, query)
_mysql_exceptions.IntegrityError: (1215, 'Cannot add foreign key constraint')
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "C:\Program Files\JetBrains\PyCharm 2017.3.2\helpers\pycharm\django_manage.py", line 52, in <module>
run_command()
File "C:\Program Files\JetBrains\PyCharm 2017.3.2\helpers\pycharm\django_manage.py", line 46, in run_command
run_module(manage_file, None, '__main__', True)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\runpy.py", line 205, in run_module
return _run_module_code(code, init_globals, run_name, mod_spec)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\runpy.py", line 96, in _run_module_code
mod_name, mod_spec, pkg_name, script_name)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\runpy.py", line 85, in _run_code
exec(code, run_globals)
File "E:/Python/DjangoProjects/rolegate\manage.py", line 15, in <module>
execute_from_command_line(sys.argv)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\__init__.py", line 371, in execute_from_command_line
utility.execute()
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\__init__.py", line 365, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\base.py", line 288, in run_from_argv
self.execute(*args, **cmd_options)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\base.py", line 335, in execute
output = self.handle(*args, **options)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\core\management\commands\migrate.py", line 200, in handle
fake_initial=fake_initial,
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 147, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\migrations\executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\base\schema.py", line 90, in __exit__
self.execute(sql)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\base\schema.py", line 117, in execute
cursor.execute(sql, params)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 100, in execute
return super().execute(sql, params)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\utils.py", line 89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\django\db\backends\mysql\base.py", line 71, in execute
return self.cursor.execute(query, args)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 250, in execute
self.errorhandler(self, exc, value)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 50, in defaulterrorhandler
raise errorvalue
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 247, in execute
res = self._query(query)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 411, in _query
rowcount = self._do_query(q)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\cursors.py", line 374, in _do_query
db.query(q)
File "C:\Users\Div-o\AppData\Local\Programs\Python\Python35-32\lib\site-packages\MySQLdb\connections.py", line 292, in query
_mysql.connection.query(self, query)
django.db.utils.IntegrityError: (1215, 'Cannot add foreign key constraint')
651
The usual cause are generally a mismatch in the type of the column of the primary table and the foreign table. It can also be a mismatch in the Engine type of two tables i.e. MyISAM or InnoDB. Datatype both columns should have same datatype. int(11) on one table and smallint(5) on another will cause problem.
The error message itself showing there is a foreign key constraint error, which means you are deleting a parent table where the child table contains the Primary table identifier as a foreign key. To avoid this error, you need to delete child table records first and after that the parent table record.
Normally it is caused by the fact that your two related tables are not using InnoDB and at least one of them uses MyISAM engine instead.
The problem is Foreign keys are not supported on MyISAM.
Here is a related Django ticket #26777.
Since this is entirely related to MYSQL and not a Django specific, I will link this thread that could potentially help you,
Converting Tables from MyISAM to InnoDB
FUN FACT
I'm not the one that took care of this Django ticket even if the names are similar. @SimonCharette is.
133
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