Python 在django迁移中使用特定日期预先填充DateTimeField

我想为已经存在的对象创建并预先填充带有特定日期的DateTimeField

型号.py

    publish_date = models.DateTimeField(verbose_name=_('publish date'))

def set_default_publish_date(apps, schema_editor):
    MyModel = apps.get_model('myapp', 'MyModel')
    MyModel.objects.all().update(publish_date=datetime.date(day=1, month=1, year=2019))


class Migration(migrations.Migration):

dependencies = [
    ('myapp', '0005_auto_20200831_1208'),
]

operations = [
    migrations.AddField(
        model_name='mymodel',
        name='publish_date',
        field=models.DateTimeField(null=True, verbose_name='publish date'),
        preserve_default=False,
    ),
    migrations.RunPython(set_default_publish_date, migrations.RunPython.noop),
    migrations.AlterField(
        model_name='mymodel',
        name='publish_date',
        field=models.DateTimeField(verbose_name='publish date'),
        preserve_default=False,
    ),
]

我首先尝试创建一个可空字段，用一些数据填充它，然后从中删除

null=True

：

迁移。py

    publish_date = models.DateTimeField(verbose_name=_('publish date'))

def set_default_publish_date(apps, schema_editor):
    MyModel = apps.get_model('myapp', 'MyModel')
    MyModel.objects.all().update(publish_date=datetime.date(day=1, month=1, year=2019))


class Migration(migrations.Migration):

dependencies = [
    ('myapp', '0005_auto_20200831_1208'),
]

operations = [
    migrations.AddField(
        model_name='mymodel',
        name='publish_date',
        field=models.DateTimeField(null=True, verbose_name='publish date'),
        preserve_default=False,
    ),
    migrations.RunPython(set_default_publish_date, migrations.RunPython.noop),
    migrations.AlterField(
        model_name='mymodel',
        name='publish_date',
        field=models.DateTimeField(verbose_name='publish date'),
        preserve_default=False,
    ),
]

由于运行迁移，我得到一个错误：

django.db.utils.OperationalError:无法更改表 “myapp_mymodel”，因为它有挂起的触发事件

---

我能做些什么来修复它呢？

只需将您的迁移分为2个或3个。您应该能够在一次mig中执行前2项操作，但不能执行第3项操作