server.js
var express = require('express');
var users = require('./routes/users');
var app = express();
//Routes
app.use('/users', users);
_______________________________________
/routes/users.js
var express     = require('express');
var user = require('../app/models/user');
var router = express.Router();

router.get('/users', function (req, res) {
  models.User.findAll()
    .then(function (users) {
    res.json(users);
  })
});
module.exports = router;
______________________________________
/models/user.js
module.exports = function(sequelize, Data) {
  var User = sequelize.define('User', {
    firstname: {
      type: Sequelize.STRING
    },
    password: {
      type: Sequelize.STRING
    },
    role: {
      type: Sequelize.STRING
    }
  });
  return User;
}

ReferenceError: models is not defined
at /home/sergei/Документы/NodeJSProjects/ParkingHouse/routes/users.js:7:5
GET /users/users 500

//Routes
app.use('/api', users);
app.use('/api', cars);