从数据库重新加载 django 对象

问题描述

是否可以从数据库中刷新 django 对象的状态?我的意思是行为大致相当于:

Is it possible to refresh the state of a django object from database? I mean behavior roughly equivalent to:

new_self = self.__class__.objects.get(pk=self.pk)
for each field of the record:
    setattr(self, field, getattr(new_self, field))

更新:在跟踪器中发现重新打开/不会修复战争:http://code.djangoproject.com/ticket/901.还是不明白为什么维护者不喜欢这个.

UPDATE: Found a reopen/wontfix war in the tracker: http://code.djangoproject.com/ticket/901.Still don't understand why the maintainers don't like this.

推荐答案

自 Django 1.8 起，刷新对象已内置.链接到文档.

As of Django 1.8 refreshing objects is built in. Link to docs.

def test_update_result(self):
    obj = MyModel.objects.create(val=1)
    MyModel.objects.filter(pk=obj.pk).update(val=F('val') + 1)
    # At this point obj.val is still 1, but the value in the database
    # was updated to 2. The object's updated value needs to be reloaded
    # from the database.
    obj.refresh_from_db()
    self.assertEqual(obj.val, 2)

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