Auto-save your object in a file, reload it automatically when your program restarts

Example

First run

// $ cat ./data.json
// no file

const data = createStore<any>("./data.json", {
  valueIfFileDoesNotExist: {},
})

// console.log(data)
// {}

data.version = "1.0.0"

// console.log(data)
// {version: "1.0.0"}

process.exit()

// $ cat ./data.json
// {"version": "1.0.0"}

Second run

// $ cat ./data.json
// {"version": "1.0.0"}

const data = createStore<any>("./data.json", {
  valueIfFileDoesNotExist: {},
})

// console.log(data)
// {"version": "1.0.0"}

Usage

const data = createStore<any>("./data.json", {
  valueIfFileDoesNotExist: {}, // object will start with this value if file is empty
  autoSaveMs: 1000 * 60, // auto checks every minute if it has changes and save if any
  noIndentJson: true, // will not indent json in saved file
})

Getting started

$ npm install savables

import { createStore } from "savables"

const data = createStore<any>("./data.json", {
  valueIfFileDoesNotExist: {},
})

Typing

You can pass a type to createStore that will enable TypeScript type-checking features

import { createStore } from "savables"

type Data = {
  users?: {
    id: number
    nickname: string
  }[]
}

const data = createStore<Data>("./data.json", { // notice the Data here
  valueIfFileDoesNotExist: {},
})

data.users = "123" // error
data.users = [] // good
data.users = [
  {
    id: 1,
    nickname: "snwfdhmp",
  }
] // good

data.users.push({
  id: 2,
  nickname: "notch",
}) // good

Implementation details

// Creating 2 stores at the same path will throw
const dataOne = createStore<Data>("./data.json", ...) // ok
const dataTwo = createStore<Data>("./data_two.json", ...) // ok
const dataThree = createStore<Data>("./data.json", ...) // throws error: Two stores cannot be created for the same path

// You can prevent object from saving
blockSave("./data.json")
saveStore("./data.json") // WARN: Tried to save store but this.blockSave is true
unblockSave("./data/json")
saveStore("./data.json") // ok

// You can perform transactions
console.log(data) // {version: "1.0.0"}
tx(data, (data) => {
  data.version = "1.0.1"
})
console.log(data) // {version: "1.0.1"}

// Transactions only apply the changes if function does not throw
tx(data, (data) => {
  data.version = "1.0.2"
  throw new Error("some error")
})
console.log(data) // {version: "1.0.1"}

// You can manually force save if you need
saveStore("./data.json") // will automatically find the right data object and save it

Also:

• When receiving signals like SIGHUP, SIGINT, SIGTERM, it will save the data before exiting
• When using process.exit(number), it will save the data before exiting