marsdb

MarsDB

MarsDB is a lightweight client-side database. It's based on a Meteor’s minimongo matching/modifying implementation. It's carefully written on ES6, have a Promise based interface and may be backed with any storage implementation (see storages). It's also supports observable cursors.

MarsDB supports any kind of find/update/remove operations that Meteor’s minimongo does. So, go to the Meteor docs for supported query/modifier operations.

You can use it in any JS environment (Browser, Electron, NW.js, Node.js).

Features

• Promise based API
• Carefully written on ES6
• Supports many of MongoDB query/modify operations – thanks to a Meteor’s minimongo
• Flexible pipeline – map, reduce, custom sorting function, filtering. All with a sexy JS interface (no ugly mongo’s aggregation language)
• Persistence API – all collections can be stored (and restored) with any kind of storage (in-memory, LocalStorage, LevelUP, etc)
• Observable queries - live queries just like in Meteor, but with simplier interface
• Reactive joins – out of the box

Bindings

• React
• AngularJS 1.x

Storage implementations

• In-memory (built-in default)
• LocalForage – fastest in-browser storage (InexedDB, WebSQL and fallback to localStorage)
• LocalStorage – not recommended, better prefer LocalForage
• LevelUP – lightweight server-less Node.js storage
• MongoDB – use MarsDB as a sugar upon MongoDB

Client-Server

• Meteor compatible Client / Server
• REST (pull-request if you need it ;))

Examples

Using within non-ES6 environment

The ./dist folder contains already compiled to a ES5 code, but some polyfills needed. For using in a browser you must to include marsdb.polyfills.js before marsdb.min.js. In node.js you need to require(‘marsdb/polyfills’). It sets in a window/global: Promise, Set and Symbol.

Create a collection

import Collection from ‘marsdb’;
import LocalStorageManager from 'marsdb-localstorage';

// Setup different id generator and storage managers
// Default storage is in-memory
Collection.defaultStorageManager(LocalStorageManager);
Collection.defaultIdGenerator(() => {
  return {
    value: Math.random(),
    seed: 0,
  };
});

const users = new Collection(‘users’);

Find documents

const posts = new Collection(‘posts’);
posts.find({author: ‘Bob’})
  .project({author: 1})
  .sort([‘createdAt’])
  .then(docs => {
    // do something with docs
  });

Find with pipeline (map, reduce, filter)

An order of pipeline methods invokation is important. Next pipeline operation gives as argument a result of a previous operation.

const posts = new Collection(‘posts’);

// Get number of all comments in the DB
posts.find()
  .limit(10)
  .sortFunc((a, b) => a - b + 10)
  .filter(doc => Matsh.sqrt(doc.comment.length) > 1.5)
  .map(doc => doc.comments.length)
  .reduce((acum, val) => acum + val)
  .then(result => {
    // result is a number of all comments
    // in all found posts
  });

// Result is `undefined` because posts
// is not exists and additional processing
// is not ran (thanks to `.ifNotEmpty()`)
posts.find({author: 'not_existing_name'})
  .aggregate(docs => docs[0])
  .ifNotEmpty()
  .aggregate(user => user.name)

Find with observing changes

Observable cursor returned by a find and findOne methods of a collection. Updates of the cursor is batched and debounced (default batch size is 20 and debounce time is 1000 / 15 ms). You can change the paramters by batchSize and debounce methods of an observable cursor (methods is chained).

const posts = new Collection(‘posts’);
const stopper = posts.find({tags: {$in: [‘marsdb’, ‘is’, ‘awesome’]}})
  .observe(docs => {
    // invoked on every result change
    // (on initial result too)
    stopper.stop(); // stops observing
  }).then(docs => {
    // invoked once on initial result
    // (after `observer` callback)
  });

Find with joins

const users = new Collection(‘users’);
const posts = new Collection(‘posts’);
posts.find()
  .join(doc => {
    // Return a Promise for waiting of the result.
    return users.findOne(doc.authorId).then(user => {
      doc.authorObj = user;
      // any return is ignored
    });
  })
  .join(doc => {
    // For reactive join you must invoke `observe` instead `then`
    // That's it!
    return users.findOne(doc.authorId).observe(user => {
      doc.authorObj = user;
    });
  })
  .join((doc, updated) => {
    // Also any other “join” mutations supported
    doc.another = _cached_data_by_post[doc._id];

    // Manually update a joined parameter and propagate
    // update event from current cursor to a root
    // (`observe` callback invoked)
    setTimeout(() => {
      doc.another = 'some another user';
      updated();
    }, 10);
  })
  .observe((posts) => {
    // do something with posts with authors
    // invoked any time when posts changed
    // (and when observed joins changed too)
  })

Inserting

const posts = new Collection(‘posts’);
posts.insert({text: ‘MarsDB is awesome’}).then(docId => {
  // Invoked after persisting document
})
posts.insertAll(
  {text: ‘MarsDB’},
  {text: ‘is’},
  {text: ‘awesome’}
).then(docsIds => {
  // invoked when all documents inserted
});

Updating

const posts = new Collection(‘posts’);
posts.update(
  {authorId: {$in: [1, 2, 3]}},
  {$set: {text: ‘noop’}}
).then(result => {
  console.log(result.modified) // count of modified docs
  console.log(result.updated) // array of updated docs
  console.log(result.original) // array of original docs
});

Removing

const posts = new Collection(‘posts’);
posts.remove({authorId: {$in: [1,2,3]}})
  .then(removedDocs => {
    // do something with removed documents array
  });

Roadmap

• Keep track of multiple remove/update documents in selector (allow only if opations.multi passed)
• Upsert updating
• Indexes support for some kind of simple requests {a: '^b'}, {a: {$lt: 9}}
• Documentation

Contributing

I’m waiting for your pull requests and issues. Don’t forget to execute gulp lint before requesting. Accepted only requests without errors.

License

See License