IndexedDB db Engine

The db system is built on LocaleForage API. It's a promise based package.

Installation

flk install @flk/db

OR

npm install @flk/db

Alias: db.

Table of contents

• Installation
• Table of contents
• Usage
• Available methods
  • Set
    • Examples
  • Get
    • Examples
  • Has
    • Examples
  • Remove
    • Examples
  • Clear
    • Examples
• Constants

Usage

Once you resolve the db object you can use the methods below.

class HomePage {
  /**
   * {@inheritDoc}
   */
  constructor(db) {
    this.db = db;
  }
}

Available methods

• set
• get
• has
• remove
• clear

Set

set(key: String, value: any, expiresAt: Number = IndexedDBEngine.FOREVER): Self

This method accepts any type of values, the db engine will handle it automatically, so if you want to store object, you don't have to JSON.stringify it, the package will take care of it.

The expiresAt parameter is used to determine until when the value should be stored in.

Please note that this method accepts a valid timestamp number, i.e Date.now().

The default value for expiresAt is set to IndexedDBEngine.FOREVER which mean the value will not be removed from the db until the user clears the browser history.

There are some useful constants for db expiration time.

Examples

let db = DI.resolve("db");

db.set("name", "Hasan")
  .then(function(value) {
    // Do other things once the value has been saved.
    console.log(value);
  })
  .catch(function(err) {
    // This code runs if there were any errors
    console.log(err);
  });

// It can also store objects
let user = {
  name: "Hasan",
  address: "Some street address"
};

db.set("user", user)
  .then(function(value) {
    // This will output the `user` object.
    console.log(value);
  })
  .catch(function(err) {
    // This code runs if there were any errors
    console.log(err);
  });

// storing arrays is acceptable as well
let users = [
  {
    name: "Hasan",
    address: "Some street address"
  },
  {
    name: "John Doe",
    address: "Another address"
  }
];

db.set("users", users)
  .then(function(value) {
    // This will output the first item in the `users` array.
    console.log(value[0]);
  })
  .catch(function(err) {
    // This code runs if there were any errors
    console.log(err);
  });

// db for one hour
db.set("accessToken", MyAccessToken, db.FOR_ONE_HOUR)
  .then(function(value) {
    console.log(value);
  })
  .catch(function(err) {
    // This code runs if there were any errors
    console.log(err);
  });

Get

get(key: String, defaultValue: any = null): any|null

Retrieve value from db.

If the key doesn't exist, defaultValue will be returned instead.

Examples

let db = DI.resolve("db");

// if the given key exists
let name = db.get("name").then(data => {
  console.log(data); // Hasan
});

// if the given key doesn't exists, return null
let age = db.get("age").then(data => {
  console.log(data); // null
});

// if the given key doesn't exists, return the given default value instead.
let email = db.get("email", "my-email@sitename.com").then(data => {
  console.log(data); // my-email@sitename.com
});

Has

has(key: String): Boolean

Determine if the given key exists in db.

Examples

let db = DI.resolve("db");

let ifKeyExists = await db.has("name");

if (ifKeyExists) {
  // do something
}

Remove

remove(key: String): void

Remove the given key if exists in db storage.

Examples

let db = DI.resolve("db");

db.remove("name").then(() => {
  console.log("Removed");
});

Clear

clear(): void

Clear all db values.

Examples

let db = DI.resolve("db");

db.clear().then(() => {
  console.log("Cleared");
});

Constants

constant	Description
IndexedDBEngine.FOR_ONE_HOUR	db the value for one hour.
IndexedDBEngine.FOR_TWO_HOURS	db the value for two hours.
IndexedDBEngine.FOR_ONE_DAY	db the value for one day.
IndexedDBEngine.FOR_ONE_WEEK	db the value for one week.
IndexedDBEngine.FOR_ONE_MONTH	db the value for one month.
IndexedDBEngine.FOR_ONE_YEAR	db the value for one year.
IndexedDBEngine.FOREVER	db the value until the visitor clears the browser history.