orbit-db-mfsstore

orbit-db-mfsstore

Key-Value database for orbit-db backed by IPFS MFS.

A key-value database backed by the IPFS Mutable File System. Also allows indexing and searching by non-primary indexes. Unlike other orbit-db stores it does not load the entire dataset into memory. Each store uses a schema and when records are inserted we build btree indexes. They get built and stored locally.

Used in orbit-db.

Table of Contents

• Install
• Usage
• API
• Contributing
• License

Install

npm install orbit-db ipfs orbit-db-mfsstore

Usage

First, create an instance of OrbitDB:

const MfsStore = require('orbit-db-mfsstore')
const IPFS = require('ipfs')
const OrbitDB = require('orbit-db')

const ipfs = new IPFS()
const orbitdb = await OrbitDB.createInstance(ipfs)

Add custom datastore type

OrbitDB.addDatabaseType("mfsstore", MfsStore)

Create a datastore with a schema. In this example we're saving baseball players. We'll add 4 different indexed fields. Indexes and can unique.

store = await orbitdb.open("baseballplayers", {
    create: true, 
    type: "mfsstore",
    schema: {
        name: { unique: false },
        currentTeam: { unique: false },
        battingHand: { unique: false },
        throwingHand: { unique: false }
    }
})

Add a record and retreive it by the primary key

  //Save it
  await store.put(101, {
      name: "Andrew McCutchen",
      currentTeam: "PIT",
      battingHand: "R",
      throwingHand: "R"
  })


  //Retreive it
  let player = await store.get(101)

Now we're going to add a few more players

  await store.put(102, {
    id: 102,
    name: "Pedro Alvarez",
    currentTeam: "BAL",
    battingHand: "R",
    throwingHand: "R"
  })

  await store.put(103, {
      id: 103,
      name: "Jordy Mercer",
      currentTeam: "PIT",
      battingHand: "L",
      throwingHand: "R"
  })

  await store.put(104, {
      id: 104,
      name: "Doug Drabek",
      currentTeam: "BAL",
      battingHand: "L",
      throwingHand: "R"
  })

Now retreive the values by the secondary indexes.

  
  //Get players who play for PIT
  let teamPIT = await store.getByIndex("currentTeam", "PIT", "desc", 0, 100)

  //Get players who who bat right handed. 
  let battingR = await store.getByIndex("battingHand", "R", "desc", 0, 100)

API

See orbit-db's API Documenations for full details.

An MFSStore has the following additional functions:

store.list(offset, limit)

• Returns a subset of the available records based on the offset and limit. Allows for paging.

//Returns the recordset starting at the first record. Returns 100 records.
let result = await store.list(0, 100)

store.getByIndex(indexName, value, sortDirection, offset, limit )

• Returns a subset of records stored in the index that match the passed in value. Offset and limit allow for paging.

//Returns the recordset of records where the currentTeam attribute is set to "PIT". 
//Sorts the records in descending order and starts at the first record. 
//Returns 100 records.
let result = await store.getByIndex("currentTeam", "PIT", "desc", 0, 100 )

store.count()

• Returns the total number of records stored in the store. Does not load the actual records into memory.

let count = await store.count()

Contributing

If you think this could be better, please open an issue!

Please note that all interactions in @orbitdb fall under our Code of Conduct.

License

MIT ©️ 2016-2018 Protocol Labs Inc., 2018 Haja Networks Oy