Django GenericForeignKey 更新

Question

我正在尝试在 Django 中将 ForeignKey 转换为 GenericForeignKey。我计划在三个迁移中执行此操作，mig1、mig2、mig3。

迁移1(mig1)有以下代码

class Migration(migrations.Migration):

    dependencies = [
        ('contenttypes', '0002_remove_content_type_name'),
        ('post_service', '0008_auto_20180802_1112'),
    ]

    operations = [
        migrations.AddField(
            model_name='comment',
            name='content_type',
            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.CASCADE, to='contenttypes.ContentType'),
        ),
        migrations.AddField(
            model_name='comment',
            name='object_id',
            field=models.PositiveIntegerField(null=True),
        ),
    ]

迁移2(mig2)有以下代码

def change_posts_to_generic_key_comment(apps, schema_editor):
    Comment  = apps.get_model('post_service', 'Comment')
    db_alias = schema_editor.connection.alias
    comments = Comment.objects.using(db_alias).all()
    for comment in comments:
        Comment.objects.filter(id=comment.id).update(content_object=comment.post)

def reverse_change_posts_to_generic_key_comment(apps, schema_editor):
    Comment  = apps.get_model('post_service', 'Comment')
    db_alias = schema_editor.connection.alias
    comments = Comment.objects.using(db_alias).all()
    for comment in comments:
        Comment.objects.filter(id=comment.id).update(content_object=)

class Migration(migrations.Migration):

    dependencies = [
        ('post_service', '0009_auto_20180802_1623'),
    ]

    operations = [
        migrations.RunPython(change_posts_to_generic_key_comment, reverse_change_posts_to_generic_key_comment),
    ]

我尝试同时使用对象的更新和直接分配
comment.content_object = content.post其次是 comment.save()
它们似乎都不起作用。我如何更新通用外键字段。

一种方法是手动设置 content_type和 object_id .有没有更好的方法来做到这一点？

编辑:评论模型

class Comment(models.Model):

    post = models.ForeignKey(Post,on_delete=models.CASCADE)

    # Fields for generic relation
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE, null=True)
    object_id = models.PositiveIntegerField(null=True)
    content_object = GenericForeignKey()

Answer 1

没有理由在这里使用过滤器和更新。你已经有了对象。

for comment in comments:
    comment.content_object = comment.post
    comment.save()