Python 从数据库重新加载 django 对象
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Reload django object from database
提问by grep
Is it possible to refresh the state of a django object from database? I mean behavior roughly equivalent to:
是否可以从数据库刷新 django 对象的状态？我的意思是行为大致相当于：
new_self = self.__class__.objects.get(pk=self.pk)
for each field of the record:
setattr(self, field, getattr(new_self, field))
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.
更新：在跟踪器中发现了重新打开/不会修复的War：http://code.djangoproject.com/ticket/901 。仍然不明白为什么维护者不喜欢这个。
采纳答案by Tim Fletcher
As of Django 1.8 refreshing objects is built in. Link to docs.
从 Django 1.8 开始，刷新对象是内置的。链接到 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)
回答by Rory
I've found it relatively easy to reload the object from the databaselike so:
我发现像这样从数据库重新加载对象相对容易：
x = X.objects.get(id=x.id)
回答by Eloff
In reference to @grep's comment, shouldn't it be possible to do:
关于@grep 的评论，难道不应该这样做：
# Put this on your base model (or monkey patch it onto django's Model if that's your thing)
def reload(self):
new_self = self.__class__.objects.get(pk=self.pk)
# You may want to clear out the old dict first or perform a selective merge
self.__dict__.update(new_self.__dict__)
# Use it like this
bar.foo = foo
assert bar.foo.pk is None
foo.save()
foo.reload()
assert bar.foo is foo and bar.foo.pk is not None
回答by Ron
As @Flimm pointed out, this is a really awesome solution:
正如@Flimm 指出的，这是一个非常棒的解决方案：
foo.refresh_from_db()
This reloads all data from the database into the object.
这会将数据库中的所有数据重新加载到对象中。
