Django.core.exceptions.FieldDoesNotExist:模型没有名为<function SET\u NULL at 0x7fc5ae8836e0>

Question

经过一些谷歌搜索，只找到了一个dead-end topic，我仍然停留在迁移问题上。

我的模型：

class CurationArticle(models.Model):

        title = models.CharField(max_length=150, null=True, blank=True)
        description = models.TextField(null=True, blank=True)
        link = models.CharField(max_length=255, null=True, blank=True)
        author = models.CharField(max_length=150, blank=True, null=True)
        author_link = models.CharField(max_length=255, blank=True, null=True)

        def __unicode__(self):
            return self.title

模型文件中的导入：

from django.template.defaultfilters import date as _date
import datetime
from django.db import models
from django.utils.text import slugify
from redactor.fields import RedactorField

数据库：

create TABLE auth_group (
    id integer not null default nextval('auth_group_id_seq'::regclass),
    name varchar(80) not null,
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX auth_group_pkey ON auth_group (id);
CREATE UNIQUE INDEX auth_group_name_key ON auth_group (name);
CREATE INDEX auth_group_name_253ae2a6331666e8_like ON auth_group (name);
create TABLE auth_group_permissions (
    id integer not null default nextval('auth_group_permissions_id_seq'::regclass),
    group_id integer not null,
    permission_id integer not null,
    PRIMARY KEY (id),
    FOREIGN KEY (group_id) REFERENCES auth_group (id),
    FOREIGN KEY (permission_id) REFERENCES auth_permission (id)
);
CREATE UNIQUE INDEX auth_group_permissions_pkey ON auth_group_permissions (id);
CREATE UNIQUE INDEX auth_group_permissions_group_id_permission_id_key ON auth_group_permissions (group_id, permission_id);
CREATE INDEX auth_group_permissions_0e939a4f ON auth_group_permissions (group_id);
CREATE INDEX auth_group_permissions_8373b171 ON auth_group_permissions (permission_id);
create TABLE auth_permission (
    id integer not null default nextval('auth_permission_id_seq'::regclass),
    name varchar(255) not null,
    content_type_id integer not null,
    codename varchar(100) not null,
    PRIMARY KEY (id),
    FOREIGN KEY (content_type_id) REFERENCES django_content_type (id)
);
CREATE UNIQUE INDEX auth_permission_pkey ON auth_permission (id);
CREATE UNIQUE INDEX auth_permission_content_type_id_codename_key ON auth_permission (content_type_id, codename);
CREATE INDEX auth_permission_417f1b1c ON auth_permission (content_type_id);
create TABLE django_admin_log (
    id integer not null default nextval('django_admin_log_id_seq'::regclass),
    action_time timestamp with time zone not null,
    object_id text,
    object_repr varchar(200) not null,
    action_flag smallint not null,
    change_message text not null,
    content_type_id integer,
    user_id integer not null,
    PRIMARY KEY (id),
    FOREIGN KEY (content_type_id) REFERENCES django_content_type (id),
    FOREIGN KEY (user_id) REFERENCES main_useraccount (id)
);
CREATE UNIQUE INDEX django_admin_log_pkey ON django_admin_log (id);
CREATE INDEX django_admin_log_417f1b1c ON django_admin_log (content_type_id);
CREATE INDEX django_admin_log_e8701ad4 ON django_admin_log (user_id);
create TABLE django_content_type (
    id integer not null default nextval('django_content_type_id_seq'::regclass),
    app_label varchar(100) not null,
    model varchar(100) not null,
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX django_content_type_pkey ON django_content_type (id);
CREATE UNIQUE INDEX django_content_type_app_label_45f3b1d93ec8c61c_uniq ON django_content_type (model, #4);
create TABLE django_migrations (
    id integer not null default nextval('django_migrations_id_seq'::regclass),
    app varchar(255) not null,
    name varchar(255) not null,
    applied timestamp with time zone not null,
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX django_migrations_pkey ON django_migrations (id);
create TABLE django_session (
    session_key varchar(40) not null,
    session_data text not null,
    expire_date timestamp with time zone not null,
    PRIMARY KEY (session_key)
);
CREATE UNIQUE INDEX django_session_pkey ON django_session (session_key);
CREATE INDEX django_session_session_key_461cfeaa630ca218_like ON django_session (session_key);
CREATE INDEX django_session_de54fa62 ON django_session (expire_date);
create TABLE main_blogpost (
    id integer not null default nextval('main_blogpost_id_seq'::regclass),
    title varchar(150) not null,
    slug varchar(255),
    image varchar(100),
    created_at varchar(150),
    updated_at varchar(150),
    published boolean not null,
    author_id integer not null,
    open_graph_description text,
    content text,
    curation_article_id integer,
    PRIMARY KEY (id),
    FOREIGN KEY (#12) REFERENCES main_curationarticle (id),
    FOREIGN KEY (open_graph_description) REFERENCES main_useraccount (id)
);
CREATE UNIQUE INDEX main_blogpost_pkey ON main_blogpost (id);
CREATE UNIQUE INDEX main_blogpost_slug_key ON main_blogpost (slug);
CREATE INDEX main_blogpost_slug_6206488e633eef95_like ON main_blogpost (slug);
CREATE INDEX main_blogpost_4f331e2f ON main_blogpost (open_graph_description);
CREATE INDEX main_blogpost_8093b65d ON main_blogpost (#12);
create TABLE main_blogpost_categories (
    id integer not null default nextval('main_blogpost_categories_id_seq'::regclass),
    blogpost_id integer not null,
    blogpostcategory_id integer not null,
    PRIMARY KEY (id),
    FOREIGN KEY (blogpostcategory_id) REFERENCES main_blogpostcategory (id)
);
CREATE UNIQUE INDEX main_blogpost_categories_pkey ON main_blogpost_categories (id);
CREATE UNIQUE INDEX main_blogpost_categories_blogpost_id_blogpostcategory_id_key ON main_blogpost_categories (blogpost_id, blogpostcategory_id);
CREATE INDEX main_blogpost_categories_53a0aca2 ON main_blogpost_categories (blogpost_id);
CREATE INDEX main_blogpost_categories_fa55acd5 ON main_blogpost_categories (blogpostcategory_id);
create TABLE main_blogpostcategory (
    id integer not null default nextval('main_blogpostcategory_id_seq'::regclass),
    name varchar(150) not null,
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX main_blogpostcategory_pkey ON main_blogpostcategory (id);
create TABLE main_curationarticle (
    id integer not null default nextval('main_curationarticle_id_seq'::regclass),
    title varchar(150),
    description text,
    link varchar(255),
    author varchar(150),
    author_link varchar(255),
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX main_curationarticle_pkey ON main_curationarticle (id);
create TABLE main_newsletteraccount (
    id integer not null default nextval('main_newsletteraccount_id_seq'::regclass),
    email varchar(254) not null,
    created_at date not null,
    is_active boolean not null,
    frequency varchar(2) not null,
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX main_newsletteraccount_pkey ON main_newsletteraccount (id);
CREATE UNIQUE INDEX main_newsletteraccount_email_key ON main_newsletteraccount (email);
CREATE INDEX main_newsletteraccount_email_71d3d7a4170cd1fe_like ON main_newsletteraccount (email);
create TABLE main_useraccount (
    id integer not null default nextval('main_useraccount_id_seq'::regclass),
    password varchar(128) not null,
    last_login timestamp with time zone,
    email varchar(254) not null,
    first_name varchar(150) not null,
    last_name varchar(150) not null,
    "position" varchar(150),
    image varchar(100),
    bio text,
    created_at date not null,
    is_active boolean not null,
    is_staff boolean not null,
    is_admin boolean not null,
    is_superuser boolean not null,
    PRIMARY KEY (id)
);
CREATE UNIQUE INDEX main_useraccount_pkey ON main_useraccount (id);
CREATE UNIQUE INDEX main_useraccount_email_68fbb6e11cf0e24_uniq ON main_useraccount (email);
create TABLE main_useraccount_groups (
    id integer not null default nextval('main_useraccount_groups_id_seq'::regclass),
    useraccount_id integer not null,
    group_id integer not null,
    PRIMARY KEY (id),
    FOREIGN KEY (useraccount_id) REFERENCES main_useraccount (id),
    FOREIGN KEY (group_id) REFERENCES auth_group (id)
);
CREATE UNIQUE INDEX main_useraccount_groups_pkey ON main_useraccount_groups (id);
CREATE UNIQUE INDEX main_useraccount_groups_useraccount_id_group_id_key ON main_useraccount_groups (useraccount_id, group_id);
CREATE INDEX main_useraccount_groups_f705e196 ON main_useraccount_groups (useraccount_id);
CREATE INDEX main_useraccount_groups_0e939a4f ON main_useraccount_groups (group_id);
create TABLE main_useraccount_user_permissions (
    id integer not null default nextval('main_useraccount_user_permissions_id_seq'::regclass),
    useraccount_id integer not null,
    permission_id integer not null,
    PRIMARY KEY (id),
    FOREIGN KEY (useraccount_id) REFERENCES main_useraccount (id),
    FOREIGN KEY (permission_id) REFERENCES auth_permission (id)
);
CREATE UNIQUE INDEX main_useraccount_user_permissions_pkey ON main_useraccount_user_permissions (id);
CREATE UNIQUE INDEX main_useraccount_user_permissi_useraccount_id_permission_id_key ON main_useraccount_user_permissions (useraccount_id, permission_id);
CREATE INDEX main_useraccount_user_permissions_f705e196 ON main_useraccount_user_permissions (useraccount_id);
CREATE INDEX main_useraccount_user_permissions_8373b171 ON main_useraccount_user_permissions (permission_id);

引用该模型的ForeignKey：

class BlogPost(models.Model):
    title = models.CharField(max_length=150)
    slug = models.CharField(max_length=255, unique=True,null=True, blank=True)
    image = models.ImageField(upload_to='blog_post_images', null=True, blank=True)
    content = RedactorField(max_length=10000, verbose_name='Redactor', null=True, blank=True)
    open_graph_description = models.TextField(null=True, blank=True)
    created_at = models.CharField(blank=True, null=True, max_length=150)
    updated_at = models.CharField(blank=True, null=True, max_length=150)
    author = models.ForeignKey('UserAccount')
    categories = models.ManyToManyField('BlogPostCategory')
    published = models.BooleanField(default=False)
    curation_article = models.ForeignKey('CurationArticle', null=True, blank=True, on_delete=models.SET_NULL)

使用migrate时的完整回溯：

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 330, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 393, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 444, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/migrate.py", line 221, in handle
    executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 110, in migrate
    self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 148, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/migration.py", line 115, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/operations/fields.py", line 201, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "/usr/local/lib/python2.7/dist-packages/django/db/backends/base/schema.py", line 456, in alter_field
    new_db_params = new_field.db_parameters(connection=self.connection)
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 2008, in db_parameters
    return {"type": self.db_type(connection), "check": []}
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 1999, in db_type
    rel_field = self.related_field
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 1902, in related_field
    return self.foreign_related_fields[0]
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 1636, in foreign_related_fields
    return tuple(rhs_field for lhs_field, rhs_field in self.related_fields)
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 1623, in related_fields
    self._related_fields = self.resolve_related_fields()
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/related.py", line 1616, in resolve_related_fields
    else self.rel.to._meta.get_field(to_field_name))
  File "/usr/local/lib/python2.7/dist-packages/django/db/models/options.py", line 554, in get_field
    raise FieldDoesNotExist('%s has no field named %r' % (self.object_name, field_name))
django.core.exceptions.FieldDoesNotExist: CurationArticle has no field named <function SET_NULL at 0x7fc5ae8836e0>

为什么models.SET_NULL要在CurationArticle中调用字段？
我敢肯定这是我自己的错。

Answer 1

在我的例子中，我删除了一个字段，但最初忘记更改唯一的_-together元属性，将删除的字段留在其中。Django显然抱怨了，我一起改变了unique_，但是迁移在migrations.RemoveField之前出现了migrations.AlterUniqueTogether，我得到了这个错误。

从以下位置更改迁移文件中的顺序后：

# -*- coding: utf-8 -*-
# Generated by Django 1.9.1 on 2016-11-04 15:00
from __future__ import unicode_literals

from django.db import migrations, models


class Migration(migrations.Migration):

    dependencies = [
        ('team', '0021_auto_20161102_1930'),
    ]

    operations = [
        migrations.RemoveField(
            model_name='csvideo',
            name='youtube',
        ),
        migrations.AlterUniqueTogether(
            name='csvideo',
            unique_together=set([('casestudy', 'platform', 'video_id')]),
        ),
    ]

致：

# -*- coding: utf-8 -*-
# Generated by Django 1.9.1 on 2016-11-04 15:00
from __future__ import unicode_literals

from django.db import migrations, models


class Migration(migrations.Migration):

    dependencies = [
        ('team', '0021_auto_20161102_1930'),
    ]

    operations = [
        migrations.AlterUniqueTogether(
            name='csvideo',
            unique_together=set([('casestudy', 'platform', 'video_id')]),
        ),
        migrations.RemoveField(
            model_name='csvideo',
            name='youtube',
        ),
    ]

。。。小美人迁移了。

希望能帮上忙