py2neo v3 属性错误：对象没有属性'db_exists'

Question

尝试使用py2neo版本3将数据导入干净的neo4j图数据库3。我已经定义了几种节点类型，如下 - 除了我没有看到节点出现在我的neo4j浏览器中。

这是相关的导入代码；我已经验证了记录是否正确加载到Python变量中。

for row in data:    
    ds = DataSource()
    #   parse Source of Information column as a list, trimming whitespace
    ds.uri = list(map(str.strip, row['data_source'].split(',')))
    ds.description = row['data_source_description']
    graph.merge(ds)

但是当我尝试做graph.exists(ds)时，我会收回以下一组错误/追溯：

Traceback (most recent call last):
  File "mydir/venv/lib/python3.5/site-packages/py2neo/database/__init__.py", line 1139, in exists
    return subgraph.__db_exists__(self)
AttributeError: 'DataSource' object has no attribute '__db_exists__'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File     "mydir/venv/lib/python3.5/site-packages/py2neo/database/__init__.py", line 478, in exists
    return self.begin(autocommit=True).exists(subgraph)
  File "mydir/venv/lib/python3.5/site-packages/py2neo/database/__init__.py", line 1141, in exists
    raise TypeError("No method defined to determine the existence of object %r" % subgraph)
TypeError: No method defined to determine the existence of object <DataSource uri=['my_uri']>

令我惊讶的是，我找不到另一个论坛上讨论这个问题。我猜想从GraphObject继承存在问题，但似乎也没有对GraphObject的__db_exists__属性的明确定义。实际上，我唯一能找到提到的属性的地方是exists函数的定义，当它生成此错误时。

有人可以看到我在这里做错了什么吗？

节点类定义如下：

class Content(GraphObject):             # group Person and Institution
    pass
class Person(Content):
    __primarykey__ = 'name'
    name = Property()
    in_scholar_names = Property()
#   
    mentored = RelatedTo('Person')
    mentored_by = RelatedFrom('Person', 'MENTORED')
    worked_alongside = Related('Person', 'WORKED_ALONGSIDE')
    studied_at = RelatedTo('Institution')
    worked_at = RelatedTo('Institution')
    tagged = RelatedTo('Tag')
    member_of = RelatedTo('Institution')
    last_update = RelatedTo('UpdateLog')
    def __lt__(self, other):
        return self.name.split()[-1] < other.name.split()[-1]
class Institution(Content):
    __primarykey__ = 'name'
#   
    name = Property()
    location = Property()
    type = Property()
    carnegie_class = Property()
#   
    students = RelatedFrom('Person', 'STUDIED_AT')
    employees = RelatedFrom('Person', 'WORKED_AT')
    members = RelatedFrom('Person', 'MEMBER_OF')
    last_update = RelatedTo('UpdateLog')
    def __lt__(self, other):
        return self.name < other.name

class User(GraphObject):
    __primarykey__ = 'username'
    username = Property()
    joined = Property()
    last_access = Property()
    active = Property()
    contributed = RelatedTo('UpdateLog')

class Provenance(GraphObject):          # group UpdateLog and DataSource
    pass    
# 
class UpdateLog(Provenance):
    __primarykey__ = 'id'
    id = Property()
    timestamp = Property()
    query = Property()
    previous = RelatedTo('UpdateLog', 'LAST_UPDATE')
    next = RelatedFrom('UpdateLog', 'LAST_UPDATE')
    based_on = RelatedTo('Provenance', 'BASED_ON')
    affected_nodes = RelatedFrom('Content', 'LAST_UPDATE')
    contributed_by = RelatedFrom('User', 'CONTRIBUTED')
class DataSource(Provenance):
    __primarykey__ = 'uri'
    id = Property()
    description = Property()
    uri = Property()
    source_for = RelatedFrom('UpdateLog', 'BASED_ON')

class Tag(GraphObject):
    __primarykey__ = 'name'
    name = Property()
    description = Property()
    see_also = Related('Tag')
    tagged = RelatedFrom('Content')

Answer 1

好吧，我想我已经弄清楚了。我一直在烧瓶的背景下学习py2neo，所有这些类别的定义对于生成给定节点上关系的视图（网页）很重要。

。

但是，对于我当前正在编写的数据导入脚本，即首先要创建节点和关系，我需要使用"节点"one_answers"关系"的香草类，然后将类型指定为功能上的参数。上面原始代码的此更新版本没有产生任何错误，并且graph.exists(ds)之后返回true：

for row in data:    
    ds = Node("DataSource")
    #   parse Source of Information column as a list, trimming whitespace
    ds['uri'] = list(map(str.strip, row['data_source'].split(',')))
    ds['description'] = row['data_source_description']
    graph.merge(ds)

另外两个注意发现：

1. 我的类继承一开始就不可能，因为我应该试图从Node继承，而不是GraphObject（即使GraphObject是在烧瓶上下文中继承的正确类）
）
2. 对于Node类，我必须使用属性的dict-style分配，带有方括号和钥匙名作为引用的字符串；点符号在这里脱离了基础，我很惊讶我没有得到更多的错误。