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Cypher

@dortdb/lang-cypher adds a Cypher-based query language to DortDB. It is the language for property graphs, data best expressed as nodes connected by relationships, and it brings Cypher's visual, ASCII-art pattern matching, including variable-length paths.

Cypher operates on labeled property graphs: nodes may carry zero or more labels, each relationship has exactly one type and a direction, and both nodes and relationships may hold properties.

Setup​

The default data adapter is backed by Graphology. Register a graph as a source and point the language at it with defaultGraph or with a FROM graph clause:

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);
Labels and types live under a symbol key

The Graphology adapter expects node labels and edge types in the gaLabelsOrType symbol-keyed attribute: { [gaLabelsOrType]: ['Person'] } for a node, { [gaLabelsOrType]: 'KNOWS' } for a relationship. A plain labels property will not be recognized, and label/type patterns like (:Person) or -[:KNOWS]- will silently match nothing. The package also exports helpers to serialize/deserialize a graph that uses these symbol keys.

Pattern matching​

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

// filter and project matched values, SQL-style
db.query(`
  MATCH (x)-[]->(y)
  WHERE y.age < 15
  RETURN x.name AS person, y.age AS age
`);

// variable-length path: friends-of-friends up to three hops away
db.query(`
  MATCH ({name: "Alice"})-[:KNOWS *1..3]->(foaf)
  RETURN foaf.name AS name
`);

A matched path may visit the same node more than once but cannot reuse the same relationship twice.

Learn more​