diskDB

A Lightweight Disk based JSON Database with a MongoDB like API for Node.

You will never know that you are interacting with a File System

Contents

• Getting Started
• Documentation
  • Connect
  • Load Collections
  • Write/Save
  • Read
  • Update
  • Remove
  • Count
• Examples
• Performance
• Contributing
• Release History

Getting Started

Install the module locally :

$ npm install diskdb

var db = require('diskdb');
db = db.connect('/path/to/db-folder', ['collection-name']);
// you can access the traditional JSON DB methods here

Documentation

Connect to DB

db.connect(pathToFolder, ['filename']);

Filename will be the name of the JSON file. You can omit the extension, diskDB will take care of it for you.

var db = require('diskdb');
db = db.connect('/examples/db', ['articles']);
// or simply
db.connect('/examples/db', ['articles']);

This will check for a directory at given path, if it does not exits, diskDB will throw an error and exit.

If the directory exists but the file/collection does not exist, diskDB will create it for you.

Note : If you have manually created an empty JSON file, please make sure that it contains at least an empty array.

[]

Else it will throw an error like

undefined:0
 
^
SyntaxError: Unexpected end of input

---

Load Collections

Alternatively you can also load collections like

var db = require('diskdb');
// this
db = db.connect('/examples/db');
db.loadCollections(['articles']);
//or
db.connect('/examples/db');
db.loadCollections(['articles']);
//or
db.connect('/examples/db')
  .loadCollections(['articles']);
//or
db.connect('/examples/db', ['articles']);

Load Multiple Collections

var db = require('diskdb');
db.connect('/examples/db', ['articles','comments','users']);

---

Write/Save to Collection

db.collectionName.save(object);

Once you have loaded a collection, you can access the collection's methods using the dot notation like

db.[collectionName].[methodname]

To save the data, you can use

var db = require('diskdb');
db.connect('db', ['articles']);
var article = {
    title : "diskDB rocks",
    published : "today",
    rating : "5 stars"
}
db.articles.save(article);
// or
db.articles.save([article]);

The saved data will be

[
    {
        "title": "diskDB rocks",
        "published": "today",
        "rating": "5 stars",
        "_id": "0f6047c6c69149f0be0c8f5943be91be"
    }
]

You can also save multiple objects at once like

var db = require('diskdb');
db.connect('db', ['articles']);
var article1 = {
    title : 'diskDB rocks',
    published : 'today',
    rating : '5 stars'
}
 
var article2 = {
    title : 'diskDB rocks',
    published : 'yesterday',
    rating : '5 stars'
}
 
var article3 = {
    title : 'diskDB rocks',
    published : 'today',
    rating : '4 stars'
}
db.articles.save([article1, article2, article3]);

And this will return the inserted objects

[ { title: 'diskDB rocks',
    published: 'today',
    rating: '4 stars',
    _id: 'b1cdbb3525b84e8c822fc78896d0ca7b' },
  { title: 'diskDB rocks',
    published: 'yesterday',
    rating: '5 stars',
    _id: '42997c62e1714e9f9d88bf3b87901f3b' },
  { title: 'diskDB rocks',
    published: 'today',
    rating: '5 stars',
    _id: '4ca1c1597ddc4020bc41b4418e7a568e' } ]

---

Read from Collection

There are 2 methods available for reading the JSON collection

• db.collectionName.find(query)
• db.collectionName.findOne(query)

db.collectionName.find()

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.find();

This will return all the records

[{
    title: 'diskDB rocks',
    published: 'today',
    rating: '5 stars',
    _id: '0f6047c6c69149f0be0c8f5943be91be'
}]

You can also query with a criteria like

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.find({rating : "5 stars"});

This will return all the articles which have a rating of 5.

Find can take multiple criteria

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.find({rating : "5 stars", published: "yesterday"});

This will return all the articles with a rating of 5, published yesterday.

Nested JSON :

var articleComments = {
    title: 'diskDB rocks',
    published: '2 days ago',
    comments: [{
        name: 'a user',
        comment: 'this is cool',
        rating: 2
    }, {
        name: 'b user',
        comment: 'this is ratchet',
        rating: 3
    }, {
        name: 'c user',
        comment: 'this is awesome',
        rating: 2
    }]
}

var savedArticle = db.articles.save([articleComments);
foundArticles = db.articles.find({rating : 2});

Since diskDB is mostly for light weight data storage, avoid nested structures and huge datasets.

db.collectionName.findOne(query)

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.findOne();

If you do not pass a query, diskDB will return the first article in the collection. If you pass a query, it will return first article in the filtered data.

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.findOne({_id: '0f6047c6c69149f0be0c8f5943be91be'});

---

Update Collection

db.collectionName.update(query, data, options);

You can also update one or many objects in the collection

options = {
    multi: false, // update multiple - default false
    upsert: false // if object is not found, add it (update-insert) - default false
}

Usage

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
 
var query = {
  title : 'diskDB rocks'
};
 
var dataToBeUpdate = {
  title : 'diskDB rocks again!',
};
 
var options = {
   multi: false,
   upsert: false
};
 
var updated = db.articles.update(query, dataToBeUpdate, options);
console.log(updated); // { updated: 1, inserted: 0 }

---

Remove Collection

db.collectionName.remove(query, multi);

You can remove the entire collection (including the file) or you can remove the matched objects by passing in a query. When you pass a query, you can either delete all the matched objects or only the first one by passing multi as false. The default value of multi is true.

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.remove({rating : "5 stars"});

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.remove({rating : "5 stars"}, true); // remove all matched. Default - multi = true

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.remove({rating : "5 stars"}, false); // remove only the first match

Using remove without any params will delete the file and will remove the db instance.

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.remove();

After the above operation db.articles is undefined.

---

Count

db.collectionName.count();

Will return the count of objects in the Collection

var db = require('diskdb');
db.connect('/examples/db', ['articles']);
db.articles.count(); // will give the count

Examples

Refer to the examples folder.

Performance

To validate diskDB's performance and to check if it meets your needs, you can clone this repo and run

$ node performance/time.js

An average of few tests (run on OS X - 10.9.3 | 2.9GHZ i7 | 8GB 1600MHz DDR3) can be found below

Time taken to process x number of objects (in ms) vs Action Performed

# of objects	1	1000	10000	100000	1000000
Save	1 ms	15 ms	137 ms	1728 ms	14425 ms
Find all without query	0 ms	2 ms	12 ms	204 ms	2923 ms
Find all with query	0 ms	2 ms	17 ms	738 ms	1985 ms
Find one without query	0 ms	1 ms	9 ms	791 ms	1676 ms
Find one with query	0 ms	1 ms	8 ms	219 ms	1410 ms
Update all records	1 ms	7 ms	61 ms	206 ms	48035 ms
Get count	0 ms	3 ms	11 ms	260 ms	2420 ms
Remove with query	0 ms	7 ms	59 ms	984 ms	48191 ms
Remove collection	0 ms	1 ms	4 ms	52 ms	154 ms
File size	0.000111 MB	0.116671 MB	1.196671 MB	12.26667 MB	125.66667 MB

Contributing

See the CONTRIBUTING Guidelines

Release History

• 0.1.x
  • Base Module with
    • Connect to a Folder
    • Access a Collection/File
    • Create Read Update Delete on JSON object
    • Minor fixes and tests
    • Performance improvements

License

Copyright (c) 2014 Arvind Ravulavaru. Licensed under the MIT license.