Question

我的bulkloader.yaml看起来像这样：

- import: models

transformers:
- model: models.Company
  connector: csv
  connector_options:
    encoding: utf_8
    columns: from_header
  property_map:
    - property: __key__
      external_name: companyid
      import_transform: int
      export_transform: transform.key_id_or_name_as_string

    - property: name
      external_name: name    

- model: models.Home
  connector: csv
  connector_options:
    encoding: utf_8
    columns: from_header
  property_map:
    - property: __key__
      external_name: listid
      import_transform: int
      export_transform: transform.key_id_or_name_as_string

    - property: companyid
      external_name: companyid
      import_transform: transform.create_foreign_key('Company')
      export_transform: transform.key_id_or_name_as_string    

    - property: address
      external_name: address    

- model: models.Bid
  connector: csv
  connector_options:
    encoding: utf_8
    columns: from_header
  property_map:
    - property: __key__
      external_name: listid
      import_transform: int    
      export_transform: transform.key_id_or_name_as_string

    - property: listid
      external_name: listid  
      import_transform: transform.create_foreign_key('Home',key_is_id=True)    
      export_transform: transform.key_id_or_name_as_string

    - property: bidtext
      external_name: bidtext    
      import_transform: db.Text

我的models.py看起来像这样

from google.appengine.ext import db

# Models
class Company(db.Model):
    """Models a real estate company"""
    companyid = db.Key()
    name = db.StringProperty()

class Home(db.Model):
    """Models an apartment, house, villa etc and its selling details"""
    listid = db.Key()
    companyid = db.ReferenceProperty(Company, collection_name='company')
    address = db.StringProperty()

class Bid(db.Model):
    """Models bidding against a listid from Home model"""
    listid = db.ReferenceProperty(Home, collection_name='biddings')
    bidtext = db.TextProperty()

我已将数据上传到我的本地开发服务器，我可以使用http://localhost:9999/_ah/admin/datastore查看数据。因此数据上传并存在。我也看到了外键。

我无法根据父对象访问子数据。它返回空。下面粘贴的是我在本地开发数据存储区的交互式控制台中执行的内容：

from google.appengine.ext import db
from models import Home,Bid,Company

#can access parent data from child i.e. Home
bd = Bid.get_by_id(4242)
hhh =  Home.get_by_id(int(bd._listid.name()))
print hhh.state

#Again, can access parent data from child i.e. Company
h = Home.get_by_id(4242)
print h.address
c = Company.get_by_id(int(h._companyid.name()))
print c.website

#Cannot find any data here (biddings is a collection name defined in Bid model)
b = Bid.gql("WHERE listid = :1", h)
for x in h.biddings:
    print x.bidtext

输出：

London
Riverview 24,
http://www.houses.com/

Answer 1

好吧，我发现我做错了什么。在我的bulkloader.yaml中，我将实体称为模型而不是实物。

一旦我用过

- kind: Home

而不是

- model: models.Home

我还在外键引用上使用了 key_is_id = True 来解决查找父子数据的问题。

现在这就是我访问父母和子女数据的方式

from google.appengine.ext import db
from models import Home,Bid,Company

#get home object
h = Home.get_by_id(4242)
print h.address

#get parent values
print h.companyid.website

#get child values
b = Bid.gql("WHERE listid = :1", h.key())
for xb in b:
    print xb.bidtext

我希望这有助于像我这样的一些菜鸟，因为我浪费了很多时间。感谢所有花时间回应这个帖子的人。

Google appengine，无法从子模型中获取数据

1 个答案: