NODES 2022

Accompanying code for my talk at the NODES 2022 conference titled: "Building a Python/Neo4j OGM".

Video

Usage

Each folder can be seen as a new "branch", where features are added incrementally.

pip install -r requirements.txt
export PYTHONPATH=.$PYTHONPATH

pytest <dir>/tests.py

 pytest 00-movie-creation/tests.py
 pytest 01-node-class/tests.py 
 pytest 02-property-attributes/tests.py
 pytest 03-manager-match/tests.py 
 pytest 04-relationship-property-fetch-and-cache/tests.py 
 pytest 05-prefetch/tests.py 

Content

• 00-movie-creation: movie class and hard-coded CREATE statement
• 01-node-class: Property and Node (w/ metaclass) => all subclasses of the Node class now have a _properties attribute with a list of properties they accept
• 02-property-attributes: define a Property as required (NB: skipped during the talk)
• 03-manager-match: dynamically build MATCH clause, RETURN statement, object hydration from DB
• 04-relationship-property-fetch-and-cache: define RelationshipProperty and ability to fetch the data when the field is accessed (ie when using movie.actors for instance)
• 05-prefetch: ability to prefetch related object during the MATCH query thanks to Cypher map projection

Map projection examples

MATCH (node:Movie {title: "Cloud Atlas"}) 
RETURN node { .* }

MATCH (node:Movie {title: "Cloud Atlas"}) 
RETURN node { .title, _id: id(node) }

MATCH (node:Movie {title: "Cloud Atlas"})
RETURN node {
     .title, 
     actors: [(node)<-[:ACTED_IN]-(person:Person) 
                 | person { .name }
            ]
}

MATCH (node:Movie {title: "Cloud Atlas"})
RETURN node {
     .title, 
     actors: [
        (node)<-[:ACTED_IN]-(person:Person) 
         | person { 
            .name, 
            directed: [
                (person)-[:DIRECTED]->(directed:Movie)
                | directed { .* }
            ] 
         }
     ]
}

Full code

The code presented here is a simplified version extracted from this project: pentaquark