interface-datastore

What is interface-datastore?

The `interface-datastore` npm package provides a set of interfaces and utilities for creating and working with datastores. It is designed to be used as a base for implementing various types of datastores, such as in-memory, file-based, or networked datastores. The package is part of the IPFS (InterPlanetary File System) project and is used to standardize how data is stored and retrieved.

What are interface-datastore's main functionalities?

Basic Operations

This feature allows you to perform basic CRUD (Create, Read, Update, Delete) operations on a datastore. The example demonstrates how to put, get, and delete a value in an in-memory datastore.

const { MemoryDatastore } = require('interface-datastore');
const datastore = new MemoryDatastore();

// Put a value
await datastore.put(new Key('/example'), Buffer.from('Hello, world!'));

// Get a value
const value = await datastore.get(new Key('/example'));
console.log(value.toString()); // 'Hello, world!'

// Delete a value
await datastore.delete(new Key('/example'));

Querying

This feature allows you to query the datastore for entries that match certain criteria. The example demonstrates how to put multiple values and then query the datastore for entries with a specific prefix.

const { MemoryDatastore } = require('interface-datastore');
const datastore = new MemoryDatastore();

// Put some values
await datastore.put(new Key('/example/1'), Buffer.from('Value 1'));
await datastore.put(new Key('/example/2'), Buffer.from('Value 2'));
await datastore.put(new Key('/example/3'), Buffer.from('Value 3'));

// Query the datastore
const query = datastore.query({ prefix: '/example' });
for await (const { key, value } of query) {
  console.log(key.toString(), value.toString());
}

Batch Operations

This feature allows you to perform multiple operations in a single batch, which can be more efficient than performing them individually. The example demonstrates how to create a batch, add operations to it, and then commit the batch.

const { MemoryDatastore } = require('interface-datastore');
const datastore = new MemoryDatastore();

// Create a batch
const batch = datastore.batch();

// Add operations to the batch
batch.put(new Key('/example/1'), Buffer.from('Value 1'));
batch.put(new Key('/example/2'), Buffer.from('Value 2'));
batch.delete(new Key('/example/3'));

// Commit the batch
await batch.commit();

Other packages similar to interface-datastore

level

The `level` package provides a simple, efficient, and flexible interface for working with LevelDB, a fast key-value storage library. It offers similar basic operations and querying capabilities but is specifically designed for use with LevelDB.

nedb

The `nedb` package is a lightweight, in-memory database with a MongoDB-like API. It offers similar CRUD operations and querying capabilities but is designed to be used as an embedded database for small applications.

pouchdb

The `pouchdb` package is a JavaScript database that syncs with CouchDB. It offers similar CRUD operations and querying capabilities but is designed for offline-first applications and synchronization with CouchDB.

README

interface-datastore

Implementation of the datastore interface in JavaScript

Lead Maintainer

Alex Potsides

Table of Contents

• Implementations
• Install
• Usage
• Api
• Contribute
• License

Implementations

• Backed Implementations
  • Memory: src/memory
  • level: datastore-level (supports any levelup compatible backend)
  • File System: datstore-fs
• Wrapper Implementations
  • Mount: datastore-core/src/mount
  • Keytransform: datstore-core/src/keytransform
  • Sharding: datastore-core/src/sharding
  • Tiered: datstore-core/src/tiered
  • Namespace: datastore-core/src/namespace

If you want the same functionality as go-ds-flatfs, use sharding with fs.

const FsStore = require('datastore-fs')
const ShardingStore = require('datastore-core').ShardingDatatstore
const NextToLast = require('datastore-core').shard.NextToLast

const fs = new FsStore('path/to/store')

// flatfs now works like go-flatfs
const flatfs = await ShardingStore.createOrOpen(fs, new NextToLast(2))

Install

$ npm install interface-datastore

The type definitions for this package are available on http://definitelytyped.org/. To install just use:

$ npm install -D @types/interface-datastore

Usage

Wrapping Stores

const MemoryStore = require('interface-datastore').MemoryDatastore
const MountStore = require('datastore-core').MountDatastore
const Key = require('interface-datastore').Key

const store = new MountStore({ prefix: new Key('/a'), datastore: new MemoryStore() })

Test suite

Available under src/tests.js

describe('mystore', () => {
  require('interface-datastore/src/tests')({
    async setup () {
      return instanceOfMyStore
    },
    async teardown () {
      // cleanup resources
    }
  })
})

API

Keys

To allow a better abstraction on how to address values, there is a Key class which is used as identifier. It's easy to create a key from a Buffer or a string.

const a = new Key('a')
const b = new Key(new Buffer('hello'))

The key scheme is inspired by file systems and Google App Engine key model. Keys are meant to be unique across a system. They are typically hierarchical, incorporating more and more specific namespaces. Thus keys can be deemed 'children' or 'ancestors' of other keys:

• new Key('/Comedy')
• new Key('/Comedy/MontyPython')

Also, every namespace can be parameterized to embed relevant object information. For example, the Key name (most specific namespace) could include the object type:

• new Key('/Comedy/MontyPython/Actor:JohnCleese')
• new Key('/Comedy/MontyPython/Sketch:CheeseShop')
• new Key('/Comedy/MontyPython/Sketch:CheeseShop/Character:Mousebender')

Methods

The exact types can be found in src/index.js.

These methods will be present on every datastore. Key always means an instance of the above mentioned Key type. Every datastore is generic over the Value type, though currently all backing implementations are implemented only for Buffer.

has(key) -> Promise<Boolean>

• key: Key

Check for the existence of a given key

const exists = await store.has(new Key('awesome'))
console.log('is it there', exists)

put(key, value) -> Promise

• key: Key
• value: Value

Store a value with the given key.

await store.put(new Key('awesome'), new Buffer('datastores'))
console.log('put content')

get(key) -> Promise<Value>

• key: Key

Retrieve the value stored under the given key.

const value = await store.get(new Key('awesome'))
console.log('got content: %s', value.toString())
// => got content: datastore

delete(key) -> Promise

• key: Key

Delete the content stored under the given key.

await store.delete(new Key('awesome'))
console.log('deleted awesome content :(')

query(query) -> Iterable

• query: Query see below for possible values

Search the store for some values. Returns an Iterable with each item being a Value.

// retrieve __all__ values from the store
let list = []
for await (const value of store.query({})) {
  list.push(value)
}
console.log('ALL THE VALUES', list)

Query

Object in the form with the following optional properties

• prefix: string (optional) - only return values where the key starts with this prefix
• filters: Array<Filter<Value>> (optional) - filter the results according to the these functions
• orders: Array<Order<Value>> (optional) - order the results according to these functions
• limit: Number (optional) - only return this many records
• offset: Number (optional) - skip this many records at the beginning
• keysOnly: Boolean (optional) - Only return keys, no values.

batch()

This will return an object with which you can chain multiple operations together, with them only being executed on calling commit.

const b = store.batch()

for (let i = 0; i < 100; i++) {
  b.put(new Key(`hello${i}`), new Buffer(`hello world ${i}`))
}

await b.commit()
console.log('put 100 values')

put(key, value)

• key: Key
• value: Value

Queue a put operation to the store.

delete(key)

• key: Key

Queue a delete operation to the store.

commit() -> Promise

Write all queued operations to the underyling store. The batch object should not be used after calling this.

open() -> Promise

Opens the datastore, this is only needed if the store was closed before, otherwise this is taken care of by the constructor.

close() -> Promise

Close the datastore, this should always be called to ensure resources are cleaned up.

Contribute

PRs accepted.

Small note: If editing the Readme, please conform to the standard-readme specification.

License

MIT 2017 © IPFS