执行generate_city命令触发IntegrityError：主键重复问题求助

我是一名Django开发者，已通过pip安装iranian_cities库并将其加入项目settings.py的INSTALLED_APPS中，但运行命令py manage.py generate_city时触发如下错误：

> (myenv) D:\myproject\math\maths>py manage.py generate_city
Traceback (most recent call last):
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\backends\utils.py", line 89, in _execute
    return self.cursor.execute(sql, params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
psycopg2.errors.UniqueViolation: duplicate key value violates unique constraint "iranian_cities_ostan_pkey"
DETAIL:  Key (id)=(1) already exists.


The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "D:\myproject\math\maths\manage.py", line 22, in <module>
    main()
  File "D:\myproject\math\maths\manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "D:\myproject\math\myenv\Lib\site-packages\django\core\management\__init__.py", line 442, in execute_from_command_line
    utility.execute()
  File "D:\myproject\math\myenv\Lib\site-packages\django\core\management\__init__.py", line 436, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "D:\myproject\math\myenv\Lib\site-packages\django\core\management\base.py", line 412, in run_from_argv
    self.execute(*args, **cmd_options)
  File "D:\myproject\math\myenv\Lib\site-packages\django\core\management\base.py", line 458, in execute
    output = self.handle(*args, **options)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\myproject\math\myenv\Lib\site-packages\iranian_cities\management\commands\generate_city.py", line 128, in handle
    self.generate_ostan(ostan_data_path)
  File "D:\myproject\math\myenv\Lib\site-packages\iranian_cities\management\commands\generate_city.py", line 37, in generate_ostan     
    Ostan.objects.bulk_create(ostan_objs)
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\models\manager.py", line 87, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\models\query.py", line 786, in bulk_create
    returned_columns = self._batched_insert(
                       ^^^^^^^^^^^^^^^^^^^^^
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\models\query.py", line 1831, in _batched_insert
    self._insert(
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\models\query.py", line 1805, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\models\sql\compiler.py", line 1822, in execute_sql
    cursor.execute(sql, params)
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\backends\utils.py", line 102, in execute
    return super().execute(sql, params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\backends\utils.py", line 67, in execute
    return self._execute_with_wrappers(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\backends\utils.py", line 80, in _execute_with_wrappers
    return executor(sql, params, many, context)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\backends\utils.py", line 84, in _execute
    with self.db.wrap_database_errors:
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\utils.py", line 91, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "D:\myproject\math\myenv\Lib\site-packages\django\db\backends\utils.py", line 89, in _execute
    return self.cursor.execute(sql, params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
django.db.utils.IntegrityError: duplicate key value violates unique constraint "iranian_cities_ostan_pkey"
DETAIL:  Key (id)=(1) already exists.

问题原因 #

iranian_cities_ostan表中已存在id=1的记录，而generate_city命令尝试再次插入相同主键的数据，违反了数据库的唯一约束规则。通常是因为你之前已经执行过该命令，或者手动向该表中添加过数据。

解决方法 #

方法一：清空已有数据后重新生成 #

这是最直接的解决方案：

1. 启动Django Shell：

py manage.py shell

2. 按外键依赖顺序清空iranian_cities库的所有相关表数据：

from iranian_cities.models import Ostan, Shahrestan, Dehestan, Abadi

Abadi.objects.all().delete()
Dehestan.objects.all().delete()
Shahrestan.objects.all().delete()
Ostan.objects.all().delete()

3. 退出Shell后重新执行生成命令：

py manage.py generate_city

方法二：重置PostgreSQL序列（仅针对PostgreSQL数据库） #

如果不想清空数据，且使用的是PostgreSQL，可能存在主键序列与实际数据不匹配的问题，可手动重置序列：

1. 连接到你的PostgreSQL数据库
2. 执行以下SQL命令：

-- 重置Ostan表的主键序列
SELECT setval('iranian_cities_ostan_id_seq', (SELECT MAX(id) FROM iranian_cities_ostan));
-- 重置Shahrestan表的主键序列
SELECT setval('iranian_cities_shahrestan_id_seq', (SELECT MAX(id) FROM iranian_cities_shahrestan));
-- 重置Dehestan表的主键序列
SELECT setval('iranian_cities_dehestan_id_seq', (SELECT MAX(id) FROM iranian_cities_dehestan));
-- 重置Abadi表的主键序列
SELECT setval('iranian_cities_abadi_id_seq', (SELECT MAX(id) FROM iranian_cities_abadi));

3. 再次执行py manage.py generate_city命令

方法三：修改命令源码（不推荐） #

可以修改iranian_cities库中generate_city.py的代码，将bulk_create替换为get_or_create逻辑，避免重复插入。但这种方法会修改第三方库源码，后续更新库时会覆盖修改，因此不推荐使用。

内容的提问来源于stack exchange，提问作者MohammadAminGHS