将模型 slug 字段迁移到现有数据库的唯一字段

Question

在旧数据库中，slug 字段不是唯一的，因此会创建重复项。现在我想迁移 slug 字段 unique=True.

slug = models.CharField(max_length=255, unique=True)

$ python manage.py migrate

django.db.utils.IntegrityError: (1062, "Duplicate entry 'some-x-slug' for key 'some_model_slug_6c7ae6ae040a5e98_uniq'")

迁移时如果 django 检测到重复的 slug 是否有可能，我想在 slug 字段的末尾添加 object_id，以使该 slug 唯一。

以上问题有什么简单的解决方法

Answer 1

使用以下 RunPython 操作更新您的迁移应该就足够了。按照 this Django guide on writing migrations 进行推理和更多示例。

your_new_migration.py

def update_slugs(apps, schema_editor):
    SomeModel = apps.get_model("some_app", "SomeModel")

    for instance in SomeModel.objects.all():
        instance.slug = '%s-%s' % (instance.slug, instance.object_id)
        instance.save()


class Migration(migrations.Migration):

    dependencies = [
        # ... your existing dependencies
    ]

    operations = [
        # add this operation ...
        migrations.RunPython(update_slugs, reverse_code=migrations.RunPython.noop),

        # ... before your original migration, such as:
        # migrations.AlterField(
        #     model_name='somemodel',
        #     name='slug',
        #     field=models.CharField(unique=True),
        # ),
    ]

将模型 slug 字段迁移到现有数据库的唯一字段

migrate model slug field to unique for existing database

python

django

django-models

django-migrations

your_new_migration.py