如何将结构化属性附加到列表，谷歌应用引擎：数据存储

Question

我必须上课评论和报告：

class comment(ndb.Model):
  date =ndb.StringProperty()
  title=ndb.StringProperty()
  name=ndb.StringProperty()
  content=ndb.TextProperty()

class report(ndb.Model):
 comments=ndb.StructuredProperty(comment,repeated=True)
 date=ndb.StringProperty()
 title=ndb.StringProperty()
 content=ndb.BlobKeyProperty()
 images=ndb.BlobKeyProperty(repeated=True)
 images_urls=ndb.StringProperty(repeated=True)

所以我将 cmets（在报告类中）声明为 ndb.StructuredProperty ，然后当我从用户那里获得评论时，我以这种方式将其附加到 cmets：

class add(webapp2.RequestHandler):
   def post(self):
     key_url=self.request.get("key")
     key=ndb.Key(urlsafe=key_url)
     report=key.get()
     title=self.request.get("title")
     name=self.request.get("name")
     date=self.request.get("date")
     content=self.request.get("content")
     new_comment=comment(date=date,title=title,name=name,content=content)
     report.comments.append(new_comment)
     report.put()
     self.redirect('/comments?'+urllib.urlencode({"key":key_url}))

实际上，当我部署项目时，它工作正常，但过了一段时间可能 30 分钟它失败了，这很奇怪！我收到此错误消息：

 Traceback (most recent call last):
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/apps/s~newseltira/1.374704102870871150/upload_comment.py", line 64, in post
    report.put()
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 3339, in _put
    return self._put_async(**ctx_options).get_result()
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 3351, in _put_async
    self._prepare_for_put()
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 3233, in _prepare_for_put
    prop._prepare_for_put(self)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 2411, in _prepare_for_put
    values = self._get_base_value_unwrapped_as_list(entity)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 1135, in _get_base_value_unwrapped_as_list
    wrapped = self._get_base_value(entity)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 1123, in _get_base_value
    return self._apply_to_values(entity, self._opt_call_to_base_type)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 1295, in _apply_to_values
    value[:] = map(function, value)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 1177, in _opt_call_to_base_type
    value = _BaseValue(self._call_to_base_type(value))
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 1198, in _call_to_base_type
    return call(value)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 1274, in call
    newvalue = method(self, value)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 2273, in _validate
    (self._modelclass.__name__, value))
BadValueError: Expected comment instance, got comment(content=u'fdsfd ds dsfdsf d', date=u'11/03/2014 03:07:25', name=u'dsfdsf', title=u'dsfdsf')

Answer 1

当我问你是否在其他地方定义了类时，你说 - 你说“是的，实际上我有，但我确信它们都是一样的，我确实复制粘贴”

这就是你的答案。

您永远不应该在多个地方定义类，因为如果它们以不同的顺序导入，在进行比较时会出现问题。

这就是堆栈跟踪告诉你的内容

File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/ndb/model.py", line 2273, in _validate
    (self._modelclass.__name__, value))
BadValueError: Expected comment instance, got comment(content=u'fdsfd ds dsfdsf d', date=u'11/03/2014 03:07:25', name=u'dsfdsf', title=u'dsfdsf')

评论的类别不匹配

在构建项目时，您应该始终遵守 DRY 的原则（不要重复自己）。

将所有类放在一个文件中，然后将它们导入到需要使用它们的任何地方。

在这种情况下，验证例程正在比较类，虽然它们可能定义相同，但它们是不同的实体。