pauladb/src/PaulaDB.js

O uso de bancos de dados não relacionais é simples, permitindo a manipulação direta dos dados de maneira fácil.

'use strict';

import { exec } from 'child_process';
import { existsSync } from 'fs';

import createSQL from 'better-sqlite3';

class PaulaDB {
  constructor({ file = '.sqlitedata' } = {}) {   
    if (!existsSync(file)) exec('touch .sqlitedata'); /* <- verify the existence of a file -> */

    this.file = file;
    this.pauladb = 'PaulaDB'

    this.database = new createSQL(this.file);
    this.database.prepare(`CREATE TABLE IF NOT EXISTS ${this.pauladb} (key TEXT, value TEXT)`).run();
  }

  set(key, value) { /* <- sets the value (key, value) -> */
    this._verifyKey(key);
    this._verifyValue(value);
  
    this.database.prepare(`INSERT INTO ${this.pauladb} (key, value) VALUES (?, ?)`).run(key, value);
  
    return value;
  }
  
  get(key) { /* <- retrieve the value of a key -> */
    this._verifyKey(key)
  
    let value = this.database.prepare(`SELECT value FROM ${this.pauladb} WHERE key = ?`).get(key)?.value;
    if (value == undefined) throw new Error('[NotFoundError] The passed key is undefined or invalid.')
  
    return value;
  }

  all() { /* <- returns the array of the table -> */
    const all = this.database.prepare(`SELECT * FROM ${this.pauladb}`).all();
    if (all.length === 0) throw new Error('[NotFoundError] No data found in the database.')
  
    return all;
  }  

  delete(key) { /* <- delete a value from the table -> */
    this._verifyKey(key)
    
    const changes = this.database.prepare(`DELETE FROM ${this.pauladb} WHERE key = ?`).run(key).changes;
    if (changes === 0) throw new Error('[NotFoundError] The passed key is undefined or invalid.');

    return changes;
  }

  _verifyKey(key) { /* <- check the key -> */
    if (!key) throw new Error("[KeyError] The provided key is not a valid string type.")
  }

  _verifyValue(value) { /* <- check the value -> */
    if (!value) throw new Error("[ValueError] Invalid second value.")
  }

}

export default PaulaDB;