books/server/postStart.js

const frappe = require('frappejs');
const naming = require('frappejs/model/naming');
const registerServerMethods = require('./registerServerMethods');

module.exports = async function postStart() {
  // set server-side modules
  frappe.models.SalesInvoice.documentClass = require('../models/doctype/SalesInvoice/SalesInvoiceServer.js');
  frappe.models.Payment.documentClass = require('../models/doctype/Payment/PaymentServer.js');
  frappe.models.Party.documentClass = require('../models/doctype/Party/PartyServer.js');
  frappe.models.PurchaseInvoice.documentClass = require('../models/doctype/PurchaseInvoice/PurchaseInvoiceServer.js');
  frappe.models.JournalEntry.documentClass = require('../models/doctype/JournalEntry/JournalEntryServer.js');
  frappe.models.GSTR3B.documentClass = require('../models/doctype/GSTR3B/GSTR3BServer.js');

  frappe.metaCache = {};

  // init naming series if missing
  await naming.createNumberSeries('SINV-', 'SalesInvoiceSettings');
  await naming.createNumberSeries('PINV-', 'PurchaseInvoiceSettings');
  await naming.createNumberSeries('PAY-', 'PaymentSettings');
  await naming.createNumberSeries('JV-', 'JournalEntrySettings');
  await naming.createNumberSeries('QTN-', 'QuotationSettings');
  await naming.createNumberSeries('SO-', 'SalesOrderSettings');
  await naming.createNumberSeries('OF-', 'FulfillmentSettings');
  await naming.createNumberSeries('PO-', 'PurchaseOrderSettings');
  await naming.createNumberSeries('PREC-', 'PurchaseReceiptSettings');

  // fetch singles
  // so that they are available synchronously
  await frappe.getSingle('SystemSettings');
  await frappe.getSingle('AccountingSettings');
  await frappe.getSingle('GetStarted');

  // cache currency symbols for frappe.format
  frappe.currencySymbols = await getCurrencySymbols();

  registerServerMethods();
};

function getCurrencySymbols() {
  return frappe.db
    .getAll({
      doctype: 'Currency',
      fields: ['name', 'symbol']
    })
    .then(data => {
      return data.reduce((obj, currency) => {
        obj[currency.name] = currency.symbol;
        return obj;
      }, {});
    });
}