python - Django 说字段不存在时它确实存在

Question

所以我在我的 Django 应用程序中创建了一个投票模型。我正在阅读 Django 网站上发布的投票应用程序教程，但是，我使用的是远程 MySQL 数据库而不是 SQLite 数据库。

from django.db import models

class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField()

class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE, default='')
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

然后我去终端输入 $ python manage.py makemigrations其次是 $ python manage.py migrate .这一切都运行得很好，并输出以下内容:

Migrations for 'polls':
polls/migrations/0001_initial.py
- Create model Question
- Create model Choice

到现在为止还挺好。但是当我尝试在 shell 中创建问题时，麻烦就来了

$ python manage.py shell
>>> from polls.models import Choice, Question
>>> from django.utils import timezone
>>> q = Question(question_text="What's new?", pub_date=timezone.now())
>>> q.save()

Traceback (most recent call last):
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/mysql/base.py", line 73, in execute
    return self.cursor.execute(query, args)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 206, in execute
    res = self._query(query)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 319, in _query
    db.query(q)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/MySQLdb/connections.py", line 259, in query
    _mysql.connection.query(self, query)
MySQLdb._exceptions.OperationalError: (1054, "Unknown column 'pub_date' in 'field list'")

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

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/models/base.py", line 727, in save
    force_update=force_update, update_fields=update_fields)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/models/base.py", line 765, in save_base
    force_update, using, update_fields,
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/models/base.py", line 868, in _save_table
    results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/models/base.py", line 908, in _do_insert
    using=using, raw=raw,
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/models/query.py", line 1270, in _insert
    return query.get_compiler(using=using).execute_sql(returning_fields)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1416, in execute_sql
    cursor.execute(sql, params)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 98, in execute
    return super().execute(sql, params)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/django/db/backends/mysql/base.py", line 73, in execute
    return self.cursor.execute(query, args)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 206, in execute
    res = self._query(query)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 319, in _query
    db.query(q)
  File "/Users/caineardayfio/Documents/CodingProjects/mysite/venv/lib/python3.7/site-packages/MySQLdb/connections.py", line 259, in query
    _mysql.connection.query(self, query)
django.db.utils.OperationalError: (1054, "Unknown column 'pub_date' in 'field list'")

有谁知道发生了什么？我知道一个事实 pub_date 是一个字段，因为当我运行 Question._meta.fields 它输出 (, , < django.db.models.fields.DateTimeField: pub_date>)
编辑
这是我运行的迁移文件。只有一个迁移文件，0001_initial.py

# Generated by Django 3.2.4 on 2021-06-15 19:24

from django.db import migrations, models
import django.db.models.deletion


class Migration(migrations.Migration):

    initial = True

    dependencies = [
    ]

    operations = [
        migrations.CreateModel(
            name='Question',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('question_text', models.CharField(max_length=200)),
                ('pub_date', models.DateTimeField()),
            ],
        ),
        migrations.CreateModel(
            name='Choice',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('choice_text', models.CharField(max_length=200)),
                ('votes', models.IntegerField(default=0)),
                ('question', models.ForeignKey(default='', on_delete=django.db.models.deletion.CASCADE, to='polls.question')),
            ],
        ),
    ]

Answer 1

我认为嫌疑人是一次不成功的迁移。让我们撤消它并重试

python manage.py migrate polls zero
python manage.py migrate