mongodb - 迁移到 0.8 后如何修复 mongoengine 取消引用错误？

Question

我刚刚升级了 mongoengine，但现在出现错误。目前，模型定义如下:

class Descriptor(Document):
    root = ReferenceField(DescriptorNode, required=True)
    (..)

class DescriptorNode(Document):
    channel = ReferenceField(Channel, required=True)
    (..)

class Channel(Document):
    (..)

使用 DBRef = True，这是我在 mongoengine==0.7.10 中使用的当前代码:

descriptor =  Descriptor.objects.get(id = xxxx)
channel = descriptor.root.channel

我选择删除 DBRef = True 以便迁移到 mongoengine==0.8.1，然后重建数据库。

现在我收到这个错误:

channel = descriptor.root.channel
AttributeError: channel
/site-packages/bson/dbref.py Line:88

我尝试了 select_related()，但似乎没有什么能正常工作。

描述符:

{
    "_id" : ObjectId("51ae3f6ba2aa1c0a32998952"),
    "created_date" : ISODate("2013-06-04T19:26:35.630Z"),
    "modified_date" : ISODate("2013-06-05T12:45:55.570Z"),
    "sequence" : 843174,
    "groups" : [ ],
    "name" : "desktop-BR",
    "root" : ObjectId("51ae3f6ba2aa1c0a329988b0"),
    "tree_hash" : "97e3716db74543e66a11405e9e04185452183ac1"
}

描述符节点:

{
    "_id" : ObjectId("51ae3f6aa2aa1c0a3299885a"),
    "channel" : ObjectId("51ae0f06a2aa1c0a327f3958"),
    "created_date" : ISODate("2013-06-04T19:26:34.235Z"),
    "groups" : [ ],
    "is_prioritized" : false,
    "is_published" : true,
    "modified_date" : ISODate("2013-06-05T12:46:02.704Z"),
    "order" : 0,
    "sequence" : 842926
}

Answer 1

你有没有和例子做的一样？

首先，将 DBRef = True 更改为 DBRef = False。其次，手动迁移:

for d in Descriptor.objects():
    d.root = d.root
    d.save()

for d in DescriptorNode.objects():
    d.channel = d.channel
    d.save()