Neo4j - GraphQL

An optimized neo4j query resolver for Facebook's GraphQL.

GraphiQL endpoint demo

Prequisites

A neo4j graph database instance is required to provide the persistence layer. You can download this from the neo4j website http://neo4j.com/.

The methodology depends on having a schema defined in neo4j as follows:

Nodes with label class represent 'classes' which correspond to graphQL object types. Class nodes have property relationships with property nodes, and the combination of these properties defines the schema of the node. Class nodes can also have extends relationships with other class nodes, thereby inheriting properties from children. The resulting aggragate of properties translates to the graphQL object type.

The image below illustrates a possible structure, with the properties Name, YearTo and YearFrom inherited by all Person types, and Title, Collection, Medium etc inherited by all Picture types.

Other relationships between classes such as Painting by Painter correspond to GraphQL List properties on the GraphQL object type.

Data nodes are then linked to schema nodes by way of instance_of relationships.

Method

Rather than having to requery the database at each node for a graphQL query, the resolver builds a single neo4j query by iterating through the graphQL request. The result is extremely performant, and enables complex queries to be generated with the user friendly graphQL syntax.