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@dortdb/lang-cypher

A Cypher-based query language plug-in for DortDB. It adds data-selection queries for property graphs: data best expressed as nodes connected by relationships, with visual ASCII-art pattern matching and variable-length paths.

The language is a set of implementation extensions to Cypher, based on the openCypher grammar (see License and attribution below).

Installation​

npm install @dortdb/core @dortdb/lang-cypher graphology

@dortdb/core and graphology are peer dependencies; graphology backs the default data adapter.

Usage​

import { DortDB } from '@dortdb/core';
import { defaultRules } from '@dortdb/core/optimizer';
import { Cypher, gaLabelsOrType } from '@dortdb/lang-cypher';
import { MultiDirectedGraph } from 'graphology';

const db = new DortDB({
  mainLang: Cypher({ defaultGraph: 'social' }),
  optimizer: { rules: defaultRules },
});

const graph = new MultiDirectedGraph();
graph.addNode('alice', { [gaLabelsOrType]: ['Person'], name: 'Alice', age: 30 });
graph.addNode('bob', { [gaLabelsOrType]: ['Person'], name: 'Bob', age: 20 });
graph.addEdge('alice', 'bob', { [gaLabelsOrType]: 'KNOWS' });

db.registerSource(['social'], graph);

db.query('MATCH (p:Person) RETURN p.name AS name ORDER BY name');

Data adapter​

The default adapter queries Graphology graphs. It expects node labels and edge types under the gaLabelsOrType symbol-keyed attribute ({ [gaLabelsOrType]: ['Person'] } for a node, { [gaLabelsOrType]: 'KNOWS' } for a relationship). A plain labels property is not recognized, so label and type patterns like (:Person) would silently match nothing.

Set the graph to query with the defaultGraph option, or per query with a FROM clause:

FROM myOtherGraph
MATCH (n)
RETURN n

Dialect​

The parser accepts the full openCypher 9 grammar, but, in keeping with DortDB's data-selection focus, only the read subset is executed. Data-writing clauses (CREATE, MERGE, SET, REMOVE, DELETE) are rejected during planning.

License and attribution​

This package derives from the openCypher grammar, which is licensed under the Apache License, Version 2.0, and was created by the collective efforts of the openCypher community.

This work is not approved by the public consensus process of the openCypher Implementers Group. In keeping with the openCypher attribution terms, it is described as implementation extensions to Cypher, not as "Cypher" or "openCypher". Cypher® is a registered trademark of Neo4j, Inc.

See the NOTICE file for the full attribution, and src/parser/cypher.pegjs for the licensed grammar.

Documentation​

See the Cypher overview and dialect reference, or the full docs at filipjezek.github.io/dortdb.

Modules​