在数据库模式中做了一些广泛的更改之后,我运行了makemigrations。它成功地创建了迁移。但随后迁移失败,原因是:
AttributeError: 'str' object has no attribute '_meta'
这是我更改的代码。我将Hardskills的多对多模型从一个直通表拆分为用户和作业的两个不同直通表
首字母
class Hardskills(models.Model):
user = models.ManyToManyField(User, related_name="user_hs",through="HardskillsProfile")
job = models.ManyToManyField(Job, related_name="job_hs",through="HardskillsProfile")
hardskills = models.CharField(max_length=100, db_index=True)
def __str__(self):
return self.hardskills
class HardskillsProfile(models.Model):
"""Through Model for Many to Many relationship for user/jobs and hardskills"""
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="user",null=True)
job = models.ForeignKey(Job, on_delete=models.CASCADE, related_name="job",null=True)
hardskills = models.ForeignKey(Hardskills, on_delete=models.CASCADE)
更改后的最终版本
from attributes.models import Category
from django.contrib.auth.models import User
from content.models import Job
from django.db import models
class Hardskills(models.Model):
user = models.ManyToManyField(User, related_name="user_hs",through="UserHardskillsProfile")
job = models.ManyToManyField(Job, related_name="job_hs",through="JobHardskillsProfile")
hardskills = models.CharField(max_length=100, db_index=True)
def __str__(self):
return self.hardskills
class UserHardskillsProfile(models.Model):
"""Through Model for Many to Many relationship for user and hardskills"""
user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="user",null=True)
hardskills = models.ForeignKey(Hardskills, on_delete=models.CASCADE)
class JobHardskillsProfile(models.Model):
"""Through Model for Many to Many relationship for user/jobs and hardskills"""
job = models.ForeignKey(Job, on_delete=models.CASCADE, related_name="job",null=True)
hardskills = models.ForeignKey(Hardskills, on_delete=models.CASCADE)
错误日志
Operations to perform:
Synchronize unmigrated apps: messages, rest_framework, staticfiles
Apply all migrations: accounts, admin, attributes, auth, authtoken, content, contenttypes, data, interactions, scoring, sessions
Synchronizing apps without migrations:
Creating tables...
Running deferred SQL...
Running migrations:
Applying scoring.0017_auto_20201224_1023...Traceback (most recent call last):
File "manage.py", line 22, in <module>
main()
File "manage.py", line 18, in main
execute_from_command_line(sys.argv)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
utility.execute()
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/core/management/__init__.py", line 395, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/core/management/base.py", line 330, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/core/management/base.py", line 371, in execute
output = self.handle(*args, **options)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/core/management/base.py", line 85, in wrapped
res = handle_func(*args, **kwargs)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/core/management/commands/migrate.py", line 245, in handle
fake_initial=fake_initial,
File "/home/yk09/miniconda3/lib/python3.7/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 "/home/yk09/miniconda3/lib/python3.7/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 "/home/yk09/miniconda3/lib/python3.7/site-packages/django/db/migrations/executor.py", line 227, in apply_migration
state = migration.apply(state, schema_editor)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/db/migrations/migration.py", line 124, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/db/migrations/operations/fields.py", line 236, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/db/backends/sqlite3/schema.py", line 138, in alter_field
super().alter_field(model, old_field, new_field, strict=strict)
File "/home/yk09/miniconda3/lib/python3.7/site-packages/django/db/backends/base/schema.py", line 555, in alter_field
old_field.remote_field.through._meta.auto_created and
AttributeError: 'str' object has no attribute '_meta'
有人能提出建议吗?如果我的问题不清楚,也请告诉我:)
在迁移文件
scoring.0017_auto_20201224_1023...
中将有操作列表。在这里,您可以找到一个删除模型迁移将其移动到迁移列表的末尾,如
来自
至
然后迁移
这个想法已经通过了。makemigrations应该处理悬空引用,如果在迁移过程中较早地删除了被引用的模型,稍后再引用,就会发生悬空引用,所以您可以手动重新排列它们
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