问题
I was playing with the django framework and I ran into an issue running the makemigration command. Here is a copy of the model and the stack trace it produces. I have seen a couple of posts with the same error but none has led me to resolve my problem here. I am working with django 1.9.4
from django.db import models
import os, uuid
# Create your models here.
def video_directory_path(instance, folder):
return os.path.join('video', str(instance.person.id), str(instance.video_id))
def photo_directory_path(instance, folder):
return os.path.join('image', str(instance.person.id), str(instance.photo_id))
class Image(models.Model):
name = models.CharField(max_length=128)
photo_id = models.UUIDField(verbose_name='photo id', default=uuid.uuid4, editable=False, unique=True)
photo = models.ImageField(upload_to=photo_directory_path)
person = models.ForeignKey('Person', on_delete=models.CASCADE)
movie = models.ForeignKey('Movie', on_delete=models.CASCADE)
class Meta:
db_table = 'Image'
def __str__(self):
return '[{0}- {1}]'.format(self.__class__.__name__, self.id)
def __repr__(self):
return self.__str__()
class Video(models.Model):
name = models.CharField(max_length=128)
video_id = models.UUIDField(verbose_name='video id', default=uuid.uuid4, editable=False, unique=True)
video = models.FileField(upload_to=video_directory_path)
person = models.ForeignKey('Person', on_delete=models.CASCADE)
movie = models.ForeignKey('Movie', on_delete=models.CASCADE)
class Meta:
db_table = 'Video'
def __str__(self):
return '[{0}-{1}]'.format(self.__class__.__name__, self.id)
def __repr__(self):
return self.__str__()
class Filmography(models.Model):
filmography = models.CharField(max_length=128, db_index=True)
class Meta:
db_table = 'Filmography'
def __str__(self):
return '[{0}-{1}]'.format(self.__class__.__name__, self.id)
def __repr__(self):
return self.__str__()
class Person(models.Model):
bio = models.TextField()
filmography = models.ManyToManyField('Filmography')
photos = models.ManyToManyField(
'Image',
through='ImagePerson',
through_fields=('person', 'photo')
)
class Meta:
abstract = True
def __str__(self):
return '[{0}-{1}]'.format(self.__class__.__name__, self.id)
def __repr__(self):
return self.__str__()
class Profile(Person):
first_name = models.CharField(max_length=128, verbose_name="first name")
last_name = models.CharField(max_length=128, verbose_name="last name")
dob = models.DateField()
class Meta:
index_together = ["first_name", "last_name"]
db_table = 'Profile'
class Character(Person):
name = models.CharField(max_length=128)
class Meta:
db_table = 'Character'
class Crew(models.Model):
name = models.CharField(max_length=256)
members = models.ManyToManyField(
'Profile',
through='MovieCrew',
through_fields=('crew', 'profile'),
)
class Meta:
db_table = 'Crew'
def __str__(self):
return '{0}: {1}'.format(self.__class__.__name__, self.name)
def __repr__(self):
return self.__str__()
class MovieCrew(models.Model):
crew = models.ForeignKey(
'Crew',
on_delete=models.CASCADE,
)
profile = models.ForeignKey(
'Profile',
on_delete=models.CASCADE,
)
role = models.CharField(max_length=256)
class Meta:
db_table = 'MovieCrew'
class Genre(models.Model):
genre = models.CharField(max_length=128, db_index=True)
class Meta:
db_table = 'Genre'
class Movie(models.Model):
name = models.CharField(max_length=128, db_index=True)
summary = models.CharField(max_length=256)
story = models.CharField(max_length=256)
release_date = models.DateField()
crew = models.OneToOneField(
'Crew',
on_delete=models.CASCADE,
)
genre = models.ManyToManyField('Genre')
photos = models.ManyToManyField('Image')
videos = models.ManyToManyField('Video')
class Meta:
db_table = 'Movie'
get_latest_by = 'release_date'
def __str__(self):
return '[{0}-{1}]'.format(self.__class__.__name__, self.name)
def __repr__(self):
return self.__str__()
and the error stacktrace
Traceback (most recent call last):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "C:\Python34\lib\site-packages\django\core\management\__init__.py", line 353, in execute_from_command_line
utility.execute()
File "C:\Python34\lib\site-packages\django\core\management\__init__.py", line 345, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "C:\Python34\lib\site-packages\django\core\management\base.py", line 348, in run_from_argv
self.execute(*args, **cmd_options)
File "C:\Python34\lib\site-packages\django\core\management\base.py", line 398, in execute
self.check()
File "C:\Python34\lib\site-packages\django\core\management\base.py", line 426, in check
include_deployment_checks=include_deployment_checks,
File "C:\Python34\lib\site-packages\django\core\checks\registry.py", line 75, in run_checks
new_errors = check(app_configs=app_configs)
File "C:\Python34\lib\site-packages\django\core\checks\model_checks.py", line 28, in check_all_models
errors.extend(model.check(**kwargs))
File "C:\Python34\lib\site-packages\django\db\models\base.py", line 1170, in check
errors.extend(cls._check_fields(**kwargs))
File "C:\Python34\lib\site-packages\django\db\models\base.py", line 1249, in _check_fields
errors.extend(field.check(from_model=cls, **kwargs))
File "C:\Python34\lib\site-packages\django\db\models\fields\related.py", line 1165, in check
errors.extend(self._check_relationship_model(**kwargs))
File "C:\Python34\lib\site-packages\django\db\models\fields\related.py", line 1366, in _check_relationship_model
for f in through._meta.fields:
AttributeError: 'str' object has no attribute '_meta'
回答1:
There doesn't seem to be a class named ImagePerson in that file which is what you are setting the through (the through table) to be in the M2M on Person.
回答2:
Indentation problem on your Crew class? Your str method here seems to be defined on the Meta:
class Crew(models.Model):
name = models.CharField(max_length=256)
members = models.ManyToManyField(
'Profile',
through='MovieCrew',
through_fields=('crew', 'profile'),
)
class Meta:
db_table = 'Crew'
def __str__(self):
return '{0}: {1}'.format(self.__class__.__name__, self.name)
def __repr__(self):
return self.__str__()
Is that really what you're after?
回答3:
For some people getting this error, don't forget to add a newly created app into Django's INSTALLED_APPS for your ManyToMany's through= intermediary model to be recognized.
来源：https://stackoverflow.com/questions/36393393/django-makemigrations-attributeerror-str-object-has-no-attribute-meta