GQLAlchemy 1.0.8

GQLAlchemy is library developed with purpose of assisting writing and running queries on Memgraph.

GQLAlchemy

GQLAlchemy is a library developed to assist in writing and running queries on Memgraph. GQLAlchemy supports high-level connection to Memgraph as well as modular query builder.

GQLAlchemy is built on top of Memgraph's low-level client pymgclient (pypi / documentation / GitHub).

Installation

Before you install gqlalchemy make sure that you have cmake installed by running:

cmake --version

You can install cmake by following the official instructions.

To install gqlalchemy, simply run the following command:

pip install gqlalchemy

Build & Test

The project uses poetry to build the GQLAlchemy. To build and run tests execute the following commands: poetry install

Before running tests make sure you have an active memgraph instance, then you can run: poetry run pytest .

GQLAlchemy example

When working with the gqlalchemy, Python developer can connect to database and execute MATCH cypher query with following syntax:

from gqlalchemy import Memgraph

memgraph = Memgraph("127.0.0.1", 7687)
memgraph.execute("CREATE (:Node)-[:Connection]->(:Node)")
results = memgraph.execute_and_fetch("""
    MATCH (from:Node)-[:Connection]->(to:Node)
    RETURN from, to;
""")

for result in results:
    print(result['from'])
    print(result['to'])

Query builder example

As we can see, the example above can be error-prone, because we do not have abstractions for creating a database connection and MATCH query.

Now, rewrite the exact same query by using the functionality of gqlalchemys query builder..

from gqlalchemy import Match, Memgraph

memgraph = Memgraph()

results = Match().node("Node",variable="from")\
                 .to("Connection")\
                 .node("Node",variable="to")\
                 .execute()

for result in results:
    print(result['from'])
    print(result['to'])

An example using the Node and Relationship classes:

from gqlalchemy import Memgraph, Node, Relationship, Match

memgraph = Memgraph("127.0.0.1", 7687)

memgraph.execute("CREATE (:Node {id: 1})-[:RELATED_TO {id: 1}]->(:Node {id: 2})")

# the first argument should be set by Memgraph
a = Node(1, ["Node"], {'id': 1})
b = Node(2, ["Node"], {'id': 2})
r = Relationship(1, "RELATED_TO", 1, 2, {'id': 1})

result = list(
    Match(memgraph.new_connection())
    .node(variable="a", node=a)
    .to(variable="r", relationship=r)
    .node(variable="b", node=b)
    .execute()
)[0]

print(result['a'])
print(result['b'])
print(result['r'])

License

Copyright (c) 2016-2021 Memgraph Ltd.

Licensed 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.