SQLite-based Key-value store for use on glitch.com node.js projects. Raw

kvstore.js

// This is a module that uses SQLite as a flat-file database to implement a simple key-value store.
//
// Exported methods:
//   get(key, callback)     - Retrieve the value for a given key in the store.
//   insert(key, value)     - Add a key/value to the store. If the key already exists, update its value.
//   getAll(callback)       - Retrieve all values in the database
//   resetdb()              - Reset the database
//
// Since this uses SQLite, it's locking and will likely have scalability issues when many concurrent users are
// accessing the database. Sequelize allows you to replace sqlite with a more production-ready database such
// as MySQL or Postgres. For a simple chat bot under 5 concurrent users this is fine.
//
// Originally designed for use in glitch projects (glitch.com).
//
// Original Author: Sam Liu ([email protected])
// License: MIT or WTFPL -- whatever you like or works best for you.
'use strict';
 
var Sequelize = require('sequelize');
 
// Start an ORM for database access. Example code here: https://glitch.com/edit/#!/sqlite3-db?path=server.js
// Setup a new database using database credentials set in `.env`.
var sequelize = new Sequelize('database', process.env.DB_USER, process.env.DB_PASS, {
  host: '0.0.0.0',
  dialect: 'sqlite',
  pool: {
    max: 5,
    min: 0,
    idle: 10000
  },
  // Security note: the database is saved to the file `database.sqlite` on the local filesystem. It's deliberately placed in the `.data` directory
  // which doesn't get copied if someone remixes the project.
  storage: '.data/database.sqlite'
});
 
// Authenticate with the database and define a new table to hold our data.
var KVStore;
sequelize.authenticate()
  .then(function(err) {
    console.log('Connection has been established successfully.');
    KVStore = sequelize.define('kvstore', {
      k: {
        type: Sequelize.STRING,
        allowNull: false,
        unique: true
      },
      v: {
        type: Sequelize.STRING,
        allowNull: false
      }
    });
  })
  .catch(function (err) {
    console.log('Unable to connect to the database: ', err);
  });
 
module.exports = {};
 
// Populate data store with default data (a single value containing )
module.exports.resetdb = function() {
  KVStore.sync({force: true}) // using 'force' it drops the table kvstore if it already exists, and creates a new one
    .then(function(){});  
}
 
// Gets all key-value pairs in the database and returns them in a list via callback.
module.exports.getAll = function(callback) {
  KVStore.findAll().then(function(kvpairs) { // find all entries in the kvstore table
    var dbContents=[];
    kvpairs.forEach(function(kvpair) {
      dbContents.push([kvpair.k,kvpair.v]); // adds their info to the dbContents value
    });
    callback(dbContents);
  });
}
 
// Retrieves a single value given a key and returns it via callback.
module.exports.get = function(key, callback) {
  KVStore.findAll({
    where: {
      k: key
    }
  }).then(function(results){
    var queryResult;
    results.forEach(function(result){
      if (result.dataValues.v) {
        queryResult = result.dataValues.v;
      }
    });
    if (queryResult) {
      callback(queryResult);
    } else {
      // If no response was sent (this query failed) just send a 404 not found.
      callback(false);
    }
  });
}
 
// Returns a promise to either update or insert the key to a new value.
module.exports.insert = function(key, value) {
  return KVStore.upsert({ k: key, v: value});
}