[GitHub] [airflow] tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT* Neo4j operator and hook
tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT*
Neo4j operator and hook
URL: https://github.com/apache/airflow/pull/6604#discussion_r351080645
##
File path: airflow/contrib/hooks/neo4j_hook.py
##
@@ -0,0 +1,106 @@
+# -*- coding: utf-8 -*-
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""This hook provides minimal thin wrapper around the neo4j python library to
provide query execution"""
+from typing import Optional
+from neo4j import BoltStatementResult, Driver, GraphDatabase, Session
+from airflow.exceptions import AirflowException
+from airflow.hooks.base_hook import BaseHook
+
+
+class Neo4JHook(BaseHook):
+"""This class enables the neo4j operator to execute queries against a
configured neo4j server.
+It requires the configuration name as set in Airflow -> Connections ->
+:param n4j_conn_id:
+:type str:
+"""
+_n4j_conn_id = None
+
+template_fields = ['n4j_conn_id']
+
+def __init__(self, n4j_conn_id: str = 'n4j_default', *args, **kwargs):
+super().__init__(*args, **kwargs)
+self._n4j_conn_id = n4j_conn_id
+
+@staticmethod
+def get_config(n4j_conn_id: Optional[str]) -> dict:
+"""
+Obtain the Username + Password from the Airflow connection definition
+Store them in _config dictionary as:
+*credentials* -- a tuple of username/password eg. ("username",
"password")
+*host* -- String for Neo4J URI eg. "bolt://1.1.1.1:7687"
+:param n4j_conn_id: Name of connection configured in Airflow
+:type n4j_conn_id: str
+:return: dictionary with configuration values
+:rtype dict
+"""
+# Initialize with empty dictionary
+config: dict = {}
+if n4j_conn_id is not None:
+connection_object = Neo4JHook.get_connection(n4j_conn_id)
+if connection_object.login and connection_object.host:
+config['credentials'] = connection_object.login,
connection_object.password
+config['host'] =
"bolt://{0}:{1}".format(connection_object.host, connection_object.port)
+else:
+raise AirflowException("No Neo4J connection:
{}".format(n4j_conn_id))
Review comment:
I have resolved this by making it require a string, `None` is not accepted
by the function. As a result, no exception is to be thrown.
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[GitHub] [airflow] tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT* Neo4j operator and hook
tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT*
Neo4j operator and hook
URL: https://github.com/apache/airflow/pull/6604#discussion_r349969408
##
File path: airflow/contrib/operators/neo4j_operator.py
##
@@ -0,0 +1,92 @@
+# -*- coding: utf-8 -*-
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from airflow.models import BaseOperator
+from airflow.utils.decorators import apply_defaults
+from airflow.exceptions import AirflowException
+from airflow.contrib.hooks.neo4j_hook import Neo4JHook
+import csv
+
+
+class Neo4JOperator(BaseOperator):
+"""
+Neo4JOperator to interact and perform action on Neo4J graph database.
+This operator is designed to use Neo4J Python driver:
https://neo4j.com/docs/api/python-driver/current/
+
+:param cypher_query: required cypher query to be executed on the Neo4J
database
+:type cypher_query: str
+:param output_filename: required filename to produce with output from the
query
+:type output_filename: str
+:param n4j_conn_id: reference to a pre-defined Neo4J Connection
+:type n4j_conn_id: str
+:param fail_on_no_results: True/False flag to indicate if it should fail
the task if no results
+:type fail_on_no_results: bool
+"""
+_cypher_query = None
+_output_filename = None
+_n4j_conn_id = None
+_fail_on_no_results = None
+
+@apply_defaults
+def __init__(self,
+ cypher_query,
+ output_filename,
+ n4j_conn_id='n4j_default',
+ fail_on_no_results=False,
+ *args,
+ **kwargs):
+super().__init__(*args, **kwargs)
+
+self._output_filename = output_filename
+self._cypher_query = cypher_query
+self._n4j_conn_id = n4j_conn_id
+self._fail_on_no_results = fail_on_no_results
+
+def execute(self, context):
+hook = Neo4JHook(n4j_conn_id=self._n4j_conn_id)
+if self._cypher_query is not None:
+result = hook.run_query(cypher_query=self._cypher_query)
+else:
+raise AirflowException("cypher_query is missing.")
+
+# In some cases, an empty result should fail (where results are
expected)
+if result.peek() is None and self._fail_on_no_results:
+raise AirflowException("Query returned no rows")
+
+row_count = self._make_csv(result)
+
+# Provide some feedback to what was done...
+self.log.info("Saved {0} with {1} rows".format(self._output_filename,
row_count))
+
+# result = 'neo4j.BoltStatementResult' See
https://neo4j.com/docs/api/python-driver/current/results.html
+self.log.info("Processing output with keys: {}".format(result.keys()))
+
+def _make_csv(self, result):
+total_row_count = 0
+
+# Consider available disk space on the Airflow server, maybe support
S3 bucket and bring in the S3 Hook
+with open(self._output_filename, 'w', newline='') as output_file:
+output_writer = csv.DictWriter(output_file,
fieldnames=result.keys())
+output_writer.writeheader()
+
+for total_row_count, row in enumerate(result, start=1):
Review comment:
Only to provide a counter to how many records were processed. It would be
good if there was a more efficient way of doing it, but I dont believe the
BoltStatementResult provides a count for read queries.
Happy to remove if its of a concern, I just felt like feedback can be useful
and this was a way of capturing something.
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[GitHub] [airflow] tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT* Neo4j operator and hook
tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT* Neo4j operator and hook URL: https://github.com/apache/airflow/pull/6604#discussion_r349969435 ## File path: docs/howto/operator/neo4j.rst ## @@ -0,0 +1,72 @@ + .. Licensed to the Apache Software Foundation (ASF) under one +or more contributor license agreements. See the NOTICE file +distributed with this work for additional information +regarding copyright ownership. The ASF licenses this file +to you under the Apache License, Version 2.0 (the +"License"); you may not use this file except in compliance +with the License. You may obtain a copy of the License at + + .. http://www.apache.org/licenses/LICENSE-2.0 + + .. Unless required by applicable law or agreed to in writing, +software distributed under the License is distributed on an +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +KIND, either express or implied. See the License for the +specific language governing permissions and limitations +under the License. + +Neo4j Operator +== + +This operator enables Airflow DAGs to execute cypher queries against a Neo4j (or ONgDB) graph database. + +The results of the query execution will be written to a CSV file on disk. Please consider available space +on the Airflow worker if your query can return a large result. + +This operator can be used in conjunction with the S3 operator or email operator to process the results. + +See the :ref:`Operators Concepts ` documentation and the :doc:`Operators API Reference <../../_api/index>` for more information. + +Prerequisite Tasks +^^ +To use this operator you must define a connection to your Neo4J/ONgDB database via: + + *Admin* -> *Connections* -> *Create* + +The connection must set the following properties: + +- login +- password +- host +- port + +The connection name is then used in the DAG to reference this definition. + +Basic Usage +^^^ +Use the :class:`~airflow/contrib/operators/neo4j_operator.Neo4JOperator` to execute cyhpher query: + +.. exampleinclude:: ../../../airflow/contrib/example_dags/example_neo4j_operator.py +:language: python +:dedent: 4 +:start-after: [START howto_operator_dingding] +:end-before: [END howto_operator_dingding] Review comment: Opps, this should be fixed now. This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
[GitHub] [airflow] tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT* Neo4j operator and hook
tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT*
Neo4j operator and hook
URL: https://github.com/apache/airflow/pull/6604#discussion_r349969134
##
File path: airflow/contrib/operators/neo4j_operator.py
##
@@ -0,0 +1,92 @@
+# -*- coding: utf-8 -*-
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from airflow.models import BaseOperator
+from airflow.utils.decorators import apply_defaults
+from airflow.exceptions import AirflowException
+from airflow.contrib.hooks.neo4j_hook import Neo4JHook
+import csv
+
+
+class Neo4JOperator(BaseOperator):
+"""
+Neo4JOperator to interact and perform action on Neo4J graph database.
+This operator is designed to use Neo4J Python driver:
https://neo4j.com/docs/api/python-driver/current/
+
+:param cypher_query: required cypher query to be executed on the Neo4J
database
+:type cypher_query: str
+:param output_filename: required filename to produce with output from the
query
+:type output_filename: str
+:param n4j_conn_id: reference to a pre-defined Neo4J Connection
+:type n4j_conn_id: str
+:param fail_on_no_results: True/False flag to indicate if it should fail
the task if no results
+:type fail_on_no_results: bool
+"""
+_cypher_query = None
+_output_filename = None
+_n4j_conn_id = None
+_fail_on_no_results = None
+
+@apply_defaults
+def __init__(self,
+ cypher_query,
+ output_filename,
+ n4j_conn_id='n4j_default',
+ fail_on_no_results=False,
+ *args,
+ **kwargs):
+super().__init__(*args, **kwargs)
+
+self._output_filename = output_filename
+self._cypher_query = cypher_query
+self._n4j_conn_id = n4j_conn_id
+self._fail_on_no_results = fail_on_no_results
+
+def execute(self, context):
+hook = Neo4JHook(n4j_conn_id=self._n4j_conn_id)
+if self._cypher_query is not None:
+result = hook.run_query(cypher_query=self._cypher_query)
+else:
+raise AirflowException("cypher_query is missing.")
Review comment:
Sure, at one point, I considered making it optional. Queries could be read
in from files or other sources, but then simplified it to just accept a string.
Have removed this to reflect how it is designed to operate right now.
Complexity can be added later if needed.
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[GitHub] [airflow] tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT* Neo4j operator and hook
tfindlay-tw commented on a change in pull request #6604: [AIRFLOW-5920] *DRAFT*
Neo4j operator and hook
URL: https://github.com/apache/airflow/pull/6604#discussion_r349968925
##
File path: airflow/contrib/hooks/neo4j_hook.py
##
@@ -0,0 +1,93 @@
+# -*- coding: utf-8 -*-
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements. See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership. The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License. You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from airflow.exceptions import AirflowException
+from airflow.hooks.base_hook import BaseHook
+from neo4j import GraphDatabase
+
+
+class Neo4JHook(BaseHook):
+"""
+Interact with Neo4J.
+This class is a thin wrapper around the neo4j python library.
+"""
+_n4j_conn_id = None
+
+def __init__(self, n4j_conn_id='n4j_default', *args, **kwargs):
+super().__init__()
+self._n4j_conn_id = n4j_conn_id
+
+@staticmethod
+def get_config(n4j_conn_id):
+"""
+Obtain the Username + Password from the Airflow connection definition
+Store them in _config dictionary as:
+ credentials = a tuple of username/password eg. ("username",
"password")
+ host = String for Neo4J URI eg. "bolt://1.1.1.1:7687"
+:return: dictionary with configuration values
+"""
+config = {}
+if n4j_conn_id:
+# Initialize with empty dictionary
+connection_object = Neo4JHook.get_connection(n4j_conn_id)
+if connection_object.login and connection_object.host:
+config['credentials'] = connection_object.login,
connection_object.password
+config['host'] =
"bolt://{0}:{1}".format(connection_object.host, connection_object.port)
+else:
+raise AirflowException("No Neo4J connection:
{}".format(n4j_conn_id))
+
+return config
+
+@staticmethod
+def get_driver(config):
+"""
+Establish a TCP connection to the server
+"""
+# Check if we already have a driver we can re-use before creating a
new one
+return GraphDatabase.driver(
+uri=config['host'],
+auth=config['credentials']
+)
+
+@staticmethod
+def get_session(driver):
+"""
+Get a neo4j.session from the driver.
+"""
+# Check if we already have a session we can re-use before creating a
new one
+return driver.session()
+
+def run_query(self, cypher_query, parameters=None):
+"""
+Uses a session to execute submit a query for execution
+:param cypher_query: Cypher query eg. MATCH (a) RETURN (a)
+:param parameters: Optional list of parameters to use with the query
+:return: neo4j.BoltStatementResult see
https://neo4j.com/docs/api/python-driver/current/results.html
+"""
+a = Neo4JHook.get_config(self._n4j_conn_id)
+b = Neo4JHook.get_driver(a)
+c = Neo4JHook.get_session(b)
Review comment:
Yes, apologies, I did name them better initially, but during testing I did
this, they should be fixed up now.
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