这就是我的models.py看起来的样子：
from django.db import models
from django.core.validators import RegexValidator
# Create your models here.
class Customer(models.Model):
customer_id = models.AutoField(primary_key=True,unique=True)
full_name = models.CharField(max_length=50)
user_email = models.EmailField(max_length=50)
user_pass = models.CharField(max_length=30)
def __str__(self):
return "%s" % self.full_name
class CustomerDetail(models.Model):
phone_regex = RegexValidator(regex = r'^\d{10}$', message = "Invalid format! E.g. 4088385778")
date_regex = RegexValidator(regex = r'\d{2}[-/]\d{2}[-/]\d{2}', message = "Invalid format! E.g. 05/16/91")
address = models.CharField(max_length=100)
date_of_birth = models.CharField(validators = [date_regex], max_length = 10, blank = True)
company = models.CharField(max_length=30)
home_phone = models.CharField(validators = [phone_regex], max_length = 10, blank = True)
work_phone = models.CharField(validators = [phone_regex], max_length = 10, blank = True)
customer_id = models.ForeignKey(Customer, on_delete=models.CASCADE)
我在customer_id中添加Customer作为外键后添加CustomerDetail。为什么在运行迁移后仍然会出现此错误，即使我已将unique=True添加到customer_id？
Error:
Rendering model states... DONE
Applying newuser.0003_auto_20160823_0128...Traceback (most recent call last):
File "/home/krag91/Documents/djangodev/virtualenv /lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/krag91/Documents/djangodev/virtualenv /lib/python3.5/site-packages/django/db/backends/sqlite3/base.py", line 337, in execute
return Database.Cursor.execute(self, query, params)
sqlite3.IntegrityError: UNIQUE constraint failed: newuser_customer.customer_id
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "manage.py", line 22, in <module>
execute_from_command_line(sys.argv)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/__init__.py", line 367, in execute_from_command_line utility.execute()
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/__init__.py", line 359, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/base.py", line 305, in run_from_argv
self.execute(*args, **cmd_options)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/base.py", line 356, in execute
output = self.handle(*args, **options)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 202, in handle
targets, plan, fake=fake, fake_initial=fake_initial
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 97, in migrate
state = self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_initial)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 132, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 237, in apply_migration
state = migration.apply(state, schema_editor)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/migration.py", line 129, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/operations/fields.py", line 84, in database_forwards
field,
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/sqlite3/schema.py", line 231, in add_field
self._remake_table(model, create_fields=[field])
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/sqlite3/schema.py", line 199, in _remake_table
self.quote_name(model._meta.db_table),
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 112, in execute
cursor.execute(sql, params)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/utils.py", line 79, in execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/utils.py", line 94, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/utils/six.py", line 685, in reraise
raise value.with_traceback(tb)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
return self.cursor.execute(sql, params)
File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/sqlite3/base.py", line 337, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.IntegrityError: UNIQUE constraint failed: newuser_customer.customer_id
答案 0 :(得分：1)
好像你是already having some objects as per old model definitions。 By default django creates a field named as id to every model in database。它可以通过modelName.id访问。
在你的情况下，我猜想发生的事情是你在数据库中有一些对象，customer.id作为主键。因此，当您更改模型并应用迁移时，existing objects are checked and another unique field is tried to added as a primary key。解决方法是在删除customer_id字段后删除所有现有对象，然后尝试重新创建字段并运行迁移。
HTH