jseg's Introduction

JavaScript Entity Graph

An 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

This is version 2 with lots of new/improved stuff and is deployed in at least one real product. I'm not personally working on that product anymore, but this version has been pretty stable and useful there, so I don't expect much if any churn. I'm unlikely to consider major feature requests, but bug fixes are still 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'));

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