JavaScript Entity Graph

A in-memory graph database for JavaScript data.

Overview

• Entity/Attribute/Value graph-based information model.
  • Schema enforces relationships, provides unique indexes, and validates data.
• Operates on plain-old JavaScript objects.
  • Hierarchical data is flattened on put and reconstituted on get.
  • Not necessarily just JSON (allows dates, etc).
• No spooky action at a distance.
  • Every graph operation makes an implicit defensive copy.
  • Many of the benefits of immutability without loss of JavaScript idioms.

Status

Expect bugs and API changes. This is version 2 with lots of new/improved stuff, but not yet battle tested.

Version 1 is in active use in one real product. Check out the v1 branch. Unlikely to see much future work, but bug fixes are welcome.

See the v1 readme for rationale, background, goals, etc.

Usage

This is just a taste. See docs for more details.

let jseg = require('jseg');

let [builder, types] = jseg.newSchema();

builder.entity('User');
builder.trait('Likeable');
builder.entity('Comment', types.Likeable);
builder.entity('Link', types.Likeable);

builder.finalize({

  attributes: {

    User: {
      name: types.Text,
    },

    Comment: {
      createdAt: types.Time,
      message: types.Text,
    },

    Link: {
      href: types.Key,
    },

  },

  relationships: [

    [[types.Likeable, 'many', 'likers'],
     [types.User, 'many', 'likes']],

    [[types.Comment, 'one', 'author'],
     [types.User, 'many', 'comments', {
       compare: (a, b) => Math.sign(a.createdAt - b.createdAt)
     }]],

  ],

});


let graph = new jseg.Graph(types);

graph.put({

  type: 'User',
  lid: 'user:brandonbloom',
  name: 'Brandon Bloom',

  comments: [
    {
      type: 'Comment',
      lid: 'comment-1',
      createdAt: new Date('Sat May 21 2016 12:59:48 GMT-0700 (PDT)'),
      message: 'It is kind of weird to like your own comments.',
    },
    {
      type: 'Comment',
      lid: 'comment-2',
      createdAt: new Date('Sat May 21 2016 12:59:51 GMT-0700 (PDT)'),
      message: 'This is a very important comment.',
    },
  ],

  likes: [
    {
      type: 'Link',
      lid: 'link-1',
      href: 'example.com',
    },
    {
      type: 'Comment',
      lid: 'comment-1',
    }
  ],

});

console.log(graph.get('user:brandonbloom'));

console.log(graph.get('comment-1', {depth: 3, json: true}));

console.log(graph.lookup('Link', 'href', 'example.com'));

graph.destroy('comment-2');
console.log(graph.get('comment-2'));