Cannot cast GraphObject to Node - neo4j

Question

I have a defined AbstractQuery as a Child of GraphObject :
class AbstractQuery(GraphObject):
__primarykey__ = "hash"
hash = Property()
projname = Property()
def __init__(self, hash):
self.hash = hash
self.projname = "" # TODO:initialize this
and iterate over all SQLQuery objects in my (already existing) graph and want to create a new AbstractQuery consisting of a hash. Any SQLQuery hashing to the hash determining the AbstractQuery should be connected:
def addAbstractionLayerSqlQueries(graph, logger=None):
abstractQueryTable = getAbstractQueries(graph, logger)
sqlqueries = graph.data("MATCH (n:SQLQuery) return n")
if logger is not None:
logger.info("abstracting {} queries".format(len(sqlqueries)))
counter = 1
for iterator in sqlqueries:
query = iterator['n']
if logger is not None:
logger.info("abstracting query {}/{}".format(counter,
len(sqlqueries)))
hash = sqlNormalizer.generate_normalized_query_hash(query['ts'])
if hash not in abstractQueryTable:
abstractQueryNode = al.AbstractQuery(hash)
abstractQueryTable[hash] = abstractQueryNode
graph.push(abstractQueryNode)
rel = Relationship(query, "ABSTRACTSTO", abstractQueryTable[hash])
graph.create(rel)
counter = counter + 1
Before I start this process I extract a table (using the hash as key) of all already existing AbstractQueries to prevent creating the same AbstractQuery twice.
However, when I run the method I end up with the exception:
TypeError: Cannot cast AbstractQuery to Node
Why is this and how can I fix this?
I previously entered multiple SQLQueries into my graph by using this representation:
class SQLQuery(GraphObject):
__primarykey__ = "uuid"
uuid = Property()
projname = Property()
session = Property()
user = Property()
seq = Property()
ts = Property()
sql = Property()
Statement = RelatedTo("SQLStatement")
AbstractsTo = RelatedTo("AbstractQuery")
def __init__(self, projname=None, session=None, user=None,
seq=None, ts=None, sql=None):
self.projname = projname
self.session = session
self.user = user
self.seq = seq
self.ts = ts
self.sql = sql
self.uuid = "{} [{} {}] {}.{}.{}".format(type(self).__name__,
seq, ts, projname,
session, user)
As I was able to use this representation to represent and enter Nodes I am quite flabbergasted on why py2neo rejects my AbstractQuery class as a node in my addAbstractionLayerSqlQueries function.

Answer 1

You're mixing two layers of API. The OGM layer sits above the regular py2neo API and a GraphObject does not directly correspond to a Node (it contains other stuff too). Therefore, you cannot build a Relationship to or from a GraphObject directly.
To access the core node behind your GraphObject, you can use my_object.__ogm__.node.

Answer 2

I fixed the problem by only using the Object Model and replacing the graph.data(...) query part:
def addAbstractionLayerSqlQueries(graph, logger=None):
abstractQueryTable = getAbstractQueries(graph, logger)
sqlqueries = list(adlsql.SQLQuery.select(graph))
print type(sqlqueries)
if logger is not None:
logger.info("abstracting {} queries".format(len(sqlqueries)))
counter = 1
for query in sqlqueries:
print type(query)
if logger is not None:
logger.info("abstracting query {}/{}".format(counter,
len(sqlqueries)))
hash = sqlNormalizer.generate_normalized_query_hash(query.ts)
if hash not in abstractQueryTable:
abstractQueryNode = al.AbstractQuery(hash)
abstractQueryTable[hash] = abstractQueryNode
graph.push(abstractQueryNode)
query.AbstractsTo.add(abstractQueryTable[hash])
graph.push(query)
counter = counter + 1
However, the actual reason for the error is still unknown and I'll accept any answer that explains this. This answer is only fixing the problem.