@admin-bro/express/src/authentication/login.handler.ts

This is an official AdminBro plugin which integrates it to expressjs framework

import AdminBro from "admin-bro";
import { Router } from "express";
import { AuthenticationOptions } from "../types";

const getLoginPath = (admin: AdminBro): string => {
  const { loginPath, rootPath } = admin.options;
  // since we are inside already namespaced router we have to replace login and logout routes that
  // they don't have rootUrl inside. So changing /admin/login to just /login.
  // but there is a case where user gives / as a root url and /login becomes `login`. We have to
  // fix it by adding / in front of the route
  const normalizedLoginPath = loginPath.replace(rootPath, "");

  return normalizedLoginPath.startsWith("/")
    ? normalizedLoginPath
    : `/${normalizedLoginPath}`;
};

export const withLogin = (
  router: Router,
  admin: AdminBro,
  auth: AuthenticationOptions
): void => {
  const { rootPath } = admin.options;
  const loginPath = getLoginPath(admin);

  router.get(loginPath, async (req, res) => {
    const login = await admin.renderLogin({
      action: admin.options.loginPath,
      errorMessage: null,
    });
    res.send(login);
  });

  router.post(loginPath, async (req, res, next) => {
    const { email, password } = req.fields as {
      email: string;
      password: string;
    };
    const adminUser = await auth.authenticate(email, password);
    if (adminUser) {
      req.session.adminUser = adminUser;
      req.session.save((err) => {
        if (err) {
          next(err);
        }
        if (req.session.redirectTo) {
          res.redirect(302, req.session.redirectTo);
        } else {
          res.redirect(302, rootPath);
        }
      });
    } else {
      const login = await admin.renderLogin({
        action: admin.options.loginPath,
        errorMessage: "invalidCredentials",
      });
      res.send(login);
    }
  });
};