LowDB

Flat JSON file database.

Serverless
Speedy
Evented
50+ methods coming from Lo-Dash

LowDB is built on Lo-Dash, this makes it quite different and unique compared to other serverless databases often based on MongoDB API.

LowDB powers JSON Server and JSONPlaceholder.

Usage

var low = require('lowdb')
low('songs').insert({title: 'low!'})

Database is automatically created and saved to db.json in a readable format.

{
  "songs": [
    {
      "title": "low!",
      "id": "e31aa48c-a9d8-4f79-9fce-ded4c16c3c4c"
    }
  ]
}

To query data, you can use Lo-Dash methods.

var songs = low('songs').where({ title: 'low!' }).value()

Or LowDB equivalent short syntax.

var songs = low('songs', { title: 'low!' })

Changes can also be monitored.

low.on('add', function(name, object) {
  console.log(object + 'added to' + name)
})

Benchmark

get    x 1000    0.837708 ms
update x 1000    4.433322 ms
insert x 1000    11.78481 ms
remove x 1000    24.60179 ms

API

low(collection)

Returns or create a Lo-Dash wrapped array.

You can then use methods like: where, find, filter, sortBy, groupBy, ... and also methods from Underscore.db.

var topFiveSongs = low('songs')
  .where({published: true})
  .sortBy('views')
  .first(5)
  .value();
  
var songTitles = low('songs')
  .pluck('titles')
  .value()
  
var total = low('songs').size()

If you just want to modify the database, without getting the returned array or object, you can omit .value()

low.save([path])

Saves database to path or low.path. By default db.json.

low.load([path])

Loads database from path or low.path. By default db.json.

low.path

Database location. By default db.json.

low.path = '/some/path/file.json'

autoSave

Set to false to disable save on change, this turns LowDB into a read-only in-memory database. By default true.

low.autoSave = true

Events

add(collectionName, insertedDoc)
update(collectionName, updatedDoc, previousDoc)
remove(collectionName, removedDoc)
change()

Short syntax

LowDB short syntax covers only the most common operations but lets you write really concise code.

low('songs', id)
// -> low('songs').get(id).value()

low('songs', {title: 'low!'})
// -> low('songs').where({title: 'low!'}).value()

low('songs', {title: 'low!'}, +1)
// -> low('songs').insert({title: 'low!'}).value()

low('songs', {title: 'low!'}, -1)
// -> low('songs').removeWhere({title: 'low!'}).value()

low('songs', id, -1)
// -> low('songs').remove(id).value()

low('songs', id, {title: 'new title'})
// -> low('songs').update(id, {title: 'new title'}).value()

low('songs', {published: false}, {published: true})
// -> low('songs').updateWhere({published: false}, {published: true}).value()

Licence

LowDB is released under the MIT License.

shyamsalimkumar / lowdb