zs-core-db/src/services/postgres.js

Servicios generales de acceso a bases de datos

const postgres = require("pg");

const CONN = {
  __db: null,
};

const timeout = (prom, time) =>
  Promise.race([prom, new Promise((_r, rej) => setTimeout(rej, time))]);

const convertParams = (sql, params) => {
  const [text, values] = Object.entries(params).reduce(
    ([sql, array, index], [key, value]) => [
      sql.replace(`:${key}`, `$${index}`),
      [...array, value],
      index + 1,
    ],
    [sql, [], 1]
  );
  return { text, values };
};

const connect = async (url) => {
  const client = new postgres.Client(url);
  await timeout(client.connect(), 5000);

  const database = url.split("/").reverse()[0];
  CONN[database] = client;
  use(database);

  this.close = close;
  this.check = check;
  this.use = use;
  this.query = query;
  this.execute = execute;
  this.commit = commit;

  return this;
};

const close = async () => CONN.__db.end();

const check = async (url) => {
  const database = url.split("/").reverse()[0];
  await timeout(CONN[database]?.query("select 1"), 1000);
};

const use = (database) => {
  CONN.__db = CONN[database];
  return this;
};

const query = async ({
  sql = "",
  bind = {},
  sort = {},
  initial = 1,
  limit = 0,
  options,
}) => {
  const minRow = `"__min_row_${new Date().getTime()}"`;

  const pagedSQL =
    `select mn.* from (\n` +
    `select mx.*, rownum ${minRow} from (\n${sql}) mx \n` +
    `where rownum <= ${limit <= 0 ? "rownum" : initial + limit - 1}` +
    `) mn \nwhere mn.${minRow} >= ${initial}`;

  const prepared = convertParams(sql, bind);
  const result = (await CONN.__db.query(prepared)).rows;
  return result;
};

const execute = async (sql, bind) =>
  (await CONN.__db.query(convertParams(sql, bind))).rowCount;

const commit = async (sql, bind) => {
  // CONN.__db.commit();
};

module.exports = {
  connect,
  close,
  check,
  use,
  query,
  execute,
  commit,
};