Nodestream Meta Plugin

This plugin allows you to build a Graph of your Graph's Schema.

Installation

pip install nodestream-plugin-meta

Meta-Schema

The schema of the graph schema is as follows:

For extra meta characteristics, the schema of the schema schema is also added to the projects schema like any other pipeline. In other words, the types NodeType, Property, and so on are added to the schema of the graph.

Getting Started

Unlike other schema plugins, this plugin uses the ingestion system to build the metagraph in your graph. That means that you need to build a pipeline to do the ingestion. For the simple case, you can build a single step pipeline that looks like this:

- implementation: nodestream_plugin_meta:SchemaRenderer

This will locate the project file located inside the current working directory (or its parent directories) and render the schema to the graph. You can also specify the path to the project file:

- implementation: nodestream_plugin_meta:SchemaRenderer
  parameters:
    project_path: /path/to/nodestream.yaml

You may also specify an overrides file to enrich the inferred schema:

- implementation: nodestream_plugin_meta:SchemaRenderer
  parameters:
    project_path: /path/to/nodestream.yaml
    overrides_path: /path/to/overrides.yaml

The overrides file should look like this:

nodes:
  - name: Person
    properties:
      is_cool:
        type: BOOLEAN
relations:
  - name: Knows
    properties:
      since:
        type: DATE

The file is merged with the inferred schema, so you can add new nodes, relations, or properties, or override parts of existing ones.

Querying the Meta Graph

The meta graph can be queried like any other graph data. For example, to get all the node types in the graph:

MATCH (n:NodeType) RETURN n.name

Or to get all the properties of a node type:

MATCH (n:NodeType {name: 'Person'})-[:HAS_PROPERTY]->(p:Property) RETURN p.name, p.type, p.is_key

Same goes for relations and their properties:

MATCH (r:RelationshipType {name: 'Knows'})-[:HAS_PROPERTY]->(p:Property) RETURN p.name, p.type, p.is_key

Also you can get the adjacencies the graph schema:

MATCH (a:NodeType)<-[:TO|FROM]-(adj:Adjacency)-[:TO|FROM]->(b:NodeType)
MATCH (adj)-[:THROUGH]->(r:RelationshipType)
RETURN a.name, r.name, b.name