需要帮助将 Gremlin 查询的结果提取到 Python 数据结构中

Question

我正在尝试从 Python 代码内部对 AWS Neptune 数据库进行 Gremlin 查询运行，并希望将返回的数据存储到 Python 列表中。这对于简单的 Gremlin 查询工作正常，但一些更复杂的查询似乎有问题。

下面是代码，第一个 Gremlin 查询工作正常，但第二个查询不行。该节点不存在，因此可以在不导入任何数据的情况下进行尝试。

from __future__  import print_function  # Python 2/3 compatibility

from gremlin_python import statics
from gremlin_python.structure.graph import Graph
from gremlin_python.process.graph_traversal import __
from gremlin_python.process.strategies import *
from gremlin_python.driver.driver_remote_connection import DriverRemoteConnection

graph = Graph()

remoteConn = DriverRemoteConnection('wss://sdm-neptune-db-instance-1.cduuicw2rgrv.us-east-1.neptune.amazonaws.com:8182/gremlin','g')
g = graph.traversal().withRemote(remoteConn)

cust_List=g.V('AZ50K115E39AX').hasLabel('tp21tpcust').count().toList()
for p in cust_List:
    print('Data Fetched: ' + str(p))

cust_List=g.V('XXXXXXXX').hasLabel('tp21tpcust').local(__.repeat(__.out().simplePath()).until(__.not_(__.out())).path().by(id).limit(100)).local(__.unfold().union(__.limit(1),__.tail()).fold()).dedup().toList()
for p in cust_List:
    print('Data Fetched' + p)

remoteConn.close()

这里是错误，任何指导将不胜感激

Data Fetched: 1
Traceback (most recent call last):
  File "TestPythonGremlin.py", line 19, in <module>
    cust_List=g.V('XXXXXXXX').hasLabel('tp21tpcust').local(__.repeat(__.out().simplePath()).until(__.not_(__.out())).path().by(id).limit(100)).local(__.unfold().union(__.limit(1),__.tail()).fold()).dedup().toList()
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/process/traversal.py", line 58, in toList
    return list(iter(self))
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/process/traversal.py", line 48, in __next__
    self.traversal_strategies.apply_strategies(self)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/process/traversal.py", line 573, in apply_strategies
    traversal_strategy.apply(traversal)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/remote_connection.py", line 149, in apply
    remote_traversal = self.remote_connection.submit(traversal.bytecode)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/driver_remote_connection.py", line 55, in submit
    result_set = self._client.submit(bytecode)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/client.py", line 127, in submit
    return self.submitAsync(message, bindings=bindings).result()
  File "/opt/Python-3.7.9/Lib/concurrent/futures/_base.py", line 428, in result
    return self.__get_result()
  File "/opt/Python-3.7.9/Lib/concurrent/futures/_base.py", line 384, in __get_result
    raise self._exception
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/connection.py", line 66, in cb
    f.result()
  File "/opt/Python-3.7.9/Lib/concurrent/futures/_base.py", line 428, in result
    return self.__get_result()
  File "/opt/Python-3.7.9/Lib/concurrent/futures/_base.py", line 384, in __get_result
    raise self._exception
  File "/opt/Python-3.7.9/Lib/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/protocol.py", line 74, in write
    request_id, request_message)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/serializer.py", line 144, in serialize_message
    message = self.build_message(request_id, processor, op, args)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/serializer.py", line 154, in build_message
    return self.finalize_message(message, b"\x21", self.version)
  File "/usr/local/lib/python3.7/site-packages/gremlin_python/driver/serializer.py", line 157, in finalize_message
    message = json.dumps(message)
  File "/opt/Python-3.7.9/Lib/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "/opt/Python-3.7.9/Lib/json/encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/opt/Python-3.7.9/Lib/json/encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "/opt/Python-3.7.9/Lib/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type builtin_function_or_method is not JSON serializable

谢谢

Answer 1

线索在错误信息中。在 Python id 中是一个内置函数。请尝试 T.id。

T是一个特殊的class/enum，可以在需要参考T.id或T.label的时候使用。它是 Apache TinkerPop Gremlin Python 客户端的一部分（通常也作为 TinkerPop 的一部分提供）。

您只需将包含定义的文件包含到您的代码中。

from gremlin_python.process.traversal import T

需要帮助将 Gremlin 查询的结果提取到 Python 数据结构中

Need Help in fetching result of Gremlin query into Python data structures

gremlin

amazon-neptune

gremlinpython