具有自定义属性的AppEngine bulkloader导出模型 [英] AppEngine bulkloader export Model with self-defined Property
问题描述
我想使用 bulkloader 通过一些自定义Property 下载模型中的所有实体。
如果我定义了这样的模型,
class MyType:
def __init __(self,arg):
self.name = arg ['name']
self.id = arg ['id']
$ b $ class MyProperty(db.Property):
def get_value_for_datastore(self ,实例):
val = super(MyProperty,self).get_value_for_datastore(instance)
如果type(val)== dict:
val = MyType(val)
return pickle (val)
$ b $ def make_value_from_datastore(self,val):
返回None如果val是None else pickle.loads(str(val))
class MyModel(db.Model):
info = MyProperty()
然后我该如何下载 MyModel
使用批量加载程序,使得文件中不会有未被清理的值?我想我应该为bulkloader.yaml中的 info
定义 export_transform
,但我不知道它应该是什么
变形金刚:
- kind:MyModel
连接符:csv
property_map:
- property:__key__
external_name:log_id
export_transform:transform.key_id_or_name_as_string
- property:info $ b $ external_name:info
export_transform:### HERE ## #
我见过 transform.py ,但仍然不知道它是如何工作的。请告诉我可以解决我的问题的任何方法。谢谢。
好的,我正在回答我自己的问题...
我仍然不知道为什么 pickle
不起作用,但改成使用 simplejson
而不是 pickle
,我可以用指定的格式成功导出 MyProperty
。
python_premable:
- import myutils
- import django.utils.simplejson
...
变形金刚:
- kind:MyModel
连接器:csv
property_map:
.. 。
- property:info
external_name:info
export_transform:myutils.load_info
并且在myutils.py load_info
中可能看起来像这样。
def load_info():
def load(x):
如果不是x:
return''
info = simplejson.loads(x)
return' %s-%s'%(in fo ['id'],info ['name'])#info的输出格式
返回加载
I want to use bulkloader to download all entities in a model with some self-defined Property.
If I define a model like this,
class MyType:
def __init__(self, arg):
self.name = arg['name']
self.id = arg['id']
class MyProperty(db.Property):
def get_value_for_datastore(self, instance):
val = super(MyProperty, self).get_value_for_datastore(instance)
if type(val) == dict:
val = MyType(val)
return pickle.dumps(val)
def make_value_from_datastore(self, val):
return None if val is None else pickle.loads(str(val))
class MyModel(db.Model):
info = MyProperty()
then how can I download MyModel
using the bulkloader such that there will not be un-pickled value in the file? I think I should define the export_transform
for info
in bulkloader.yaml, but I don't know what it should be like.
transformers:
- kind: MyModel
connector: csv
property_map:
- property: __key__
external_name: log_id
export_transform: transform.key_id_or_name_as_string
- property: info
external_name: info
export_transform: ### HERE ###
I've seen transform.py but still have no idea about how it works. Please tell my any method that can solve my problem. Thanks.
Okay I'm answering my own questions...
I still don't know why pickle
doesn't work, but after changing to use simplejson
instead of pickle
, I can successfully export MyProperty
in the designated format.
The bulkloader.yaml may look like this.
python_preamable:
- import myutils
- import django.utils.simplejson
...
transformers:
- kind: MyModel
connector: csv
property_map:
...
- property: info
external_name: info
export_transform: myutils.load_info
And in myutils.py load_info
may look like this.
def load_info():
def load(x):
if not x:
return ''
info = simplejson.loads(x)
return '%s-%s' % (info['id'], info['name']) # the output format for info
return load
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