I'm trying to reuse my controllers which handle database operations. I'm bit struggling with structuring my application. Here's what I have:
server.js
var apiController = require('./controllers/api');
router.get('/cars', function (req, res) {
// get all cars from DB and render view
apiController.getCars().then(function (cars) {
res.render('index', {cars: cars});
});
});
router.get('/api/cars', function (req, res) {
// get all cars from DB and return JSON
apiController.getCars().then(function (cars) {
res.json(cars);
});
});
controllers/api.js
module.exports = {
getCars: function () {
db.collection('cars').find().toArray( function (err, cars) {
if (err) throw err;
return cars;
});
},
// tried also something like this but this doesn't really work
// for my use case because I don't want to attach any particular
// res to the function
getCars: function (req, res, next) {
db.collection('cars').find().toArray( function (err, cars) {
if (err) throw err;
res.json(cars);
});
},
};
Your current problem is that you expect promises as return in server.js while you use callbacks in the controller. I suggest you change your function getCars to return a Promise. Don't know what ODM/ORM you're using but it might look like something like this:
getCars: function () {
return db.collection('cars').find();
},
server.js
var apiController = require('./controllers/api');
router.get('/cars', function (req, res) {
apiController.get('cars').then(function (cars) {
res.render('index', {cars: cars});
});
});
router.get('/api/cars', function (req, res) {
apiController.get('cars').then(function (cars) {
res.json(cars);
});
});
controllers/api.js
var Promise = require('bluebird');
module.exports = {
get: function (modelName) {
return new Promise(function(resolve,reject){
return db.collection(modelName).find().toArray(function(err, models){
if (err) {
return reject(err);
}
else {
return resolve(models);
}
});
});
}
};
server.js
var apiController = require('./controllers/api');
router.get('/cars', apiController.getCars);
controllers/api.js
function getCarsAsync(req, res, next){
db.collection('cars').find().then(function(carsData){
if(carsData){
return res.send(carsData);
}
else{
return res.status(401).send('User is not authorized');
}
}).catch(function(err){
return next(err);
});
}
module.exports = {
getCars: getCarsAsync
};
Related
I have a router like that:
app.get('/rest/userList', (req, res) => {
UserList.find({}, (err, users) => {
if (err) res.send(err);
res.json(users);
});
});
I would like to change it like this:
app.get('/rest/userList', getUsers);
function getUsers(req, res) {
UserList.find({}, createResponse);
}
function createResponse(err, users) {
if (err) return res.send(err);
return res.send(users);
}
However; in createResponse function 'res' is undefined. How can I do that?
You can use .bind() to bind extra parameters to the callback:
app.get('/rest/userList', getUsers);
function getUsers(req, res) {
UserList.find({}, createResponse.bind(null, res));
}
function createResponse(res, err, users) {
if (err) return res.send(err);
return res.send(users);
}
app.get('/rest/userList', getUsers, createResponse);
function getUsers(req, res, next) {
UserList.find({}, function (err, users) {
if (err) {
req.errr = err;
} else {
req.users = users;
}
next();
});
}
function createResponse(req, res) {
if (req.err) return res.send(req.err);
return res.send(req.users);
}
i am not able to access the function create outside the sockets.
i want to basically export it and use in the middleware by requiring it.
socket.on('init', function (req) {
database=mongoose.connection;
var dbname=database.useDb(req.db);
var Observer =dbname.model('ObserverEvent');
exports.create = function (req, res) {
var observer = new Observer(req.body);
observer.user = req.user;
observer.save(function (err) {
if (err) {
return res.status(400).send({
message: errorHandler.getErrorMessage(err)
});
} else {
res.jsonp(observer);
}
});
}
I am new to Node.JS coming from a Java Background I am using express to build this Rest API . What I am trying to do is build the concept of a manager. I am looking for a elegant way of returning a user object in the following:
users route: user.js
router.get('/find/:email', function(req, res, next){
userWare.findUserByEmail(req, res, next)
});
middleware/manager: usermiddleware.js
module.exports = {
findUserByEmail: function(req, res, next) {
models.core_user.find({
where:{
email: req.params.email
}
}).then(function(user){
res.json(user)
}, function(err){
res.status(404).json(err);
});
},
}
So In this above function I would like to return the user object to the route instead of the json. so that I can create the json from the object in the route. The whole point of this manager class will be to fectch and return objects.
What you need to do is call the callback function with the data you need or return the promise.
Callback
user.js
router.get('/find/:email', function (req, res, next) {
userWare.findUserByEmail(req.params.email, function (err, data) {
// error as first parameter or null if no error occurred
if (err) {
return res.status(404).json(err);
}
res.json(user);
});
});
usermiddleware.js
module.exports = {
findUserByEmail: function (email, next) {
models.core_user.find({
where: {
email: email
}
}).then(
function (user) {
// async call of callback with user object
next(null, user);
},
function (err) {
// async call of callback with error
next(err);
}
);
}
};
Promise
You could also just return the promise returned by your model, then it would look like this:
user.js
router.get('/find/:email', function (req, res, next) {
userWare.findUserByEmail(req.params.email).then(
function (user) {
res.json(user);
},
function (err) {
res.status(404).json(err)
}
);
});
usermiddleware.js
module.exports = {
findUserByEmail: function (email) {
// return the promise to the caller
return models.core_user.find({
where: {
email: email
}
});
}
};
I'm a beginner in Node/Express. I tried to make an CRUD application but stuck at update and delete. I think my router code is problematic but I don't know why. The following code is in my controller, everything works but PUT and DELETE. It always route to GET. I tried to use next(); but it returns this error: Can't set headers after they are sent..
I can make the delete works by using GET /:company_id/delete but it's not a good and standardized solution. How can I get update and delete process worked?
'use strict';
var Companies = require('../../models/companies');
module.exports = function (router) {
// INDEX
// accessed at GET http://localhost:8000/companies
router.get('/', function (req, res) {
Companies.find(function(err, model) {
if (err) {
res.send(err);
}
else {
res.format({
json: function () {
res.json(model);
},
html: function () {
res.render('companies/index', model);
}
});
}
});
});
// CREATE VIEW
// accessed at GET http://localhost:8000/companies/create
router.get('/create', function (req, res) {
res.render('companies/create');
});
// CREATE DATA
// accessed at POST http://localhost:8000/companies
router.post('/', function (req, res) {
var name = req.body.name && req.body.name.trim();
var type = req.body.type && req.body.type.trim();
// VALIDATION
if (name === '') {
res.redirect('/companies/create');
return;
}
var model = new Companies({name: name, type: type});
model.save(function(err) {
if (err) {
res.send(err);
}
else {
res.redirect('/companies');
}
});
});
// READ
// accessed at GET http://localhost:8000/companies/:company_id
router.get('/:company_id', function(req, res) {
Companies.findById(req.params.company_id, function(err, model) {
if (err) {
res.send(err);
}
else {
res.render('companies/read', model);
}
});
});
// UPDATE VIEW
// accessed at GET http://localhost:8000/companies/:company_id/edit
router.get('/:company_id/edit', function(req, res) {
Companies.findById(req.params.company_id, function(err, model) {
if (err) {
res.send(err);
}
else {
res.render('companies/edit', model);
}
});
});
// UPDATE DATA
// accessed at PUT http://localhost:8000/companies/:company_id
router.put('/:company_id', function(req, res) {
Companies.findById(req.params.company_id, function(err, model) {
if (err) {
res.send(err);
}
else {
model.name = req.body.name;
model.type = req.body.type;
model.save(function(err) {
if (err) {
res.send(err);
}
else {
res.redirect('/companies');
}
});
}
});
});
// DELETE
// accessed at DELETE http://localhost:8000/companies/:company_id
router.delete('/:company_id', function (req, res) {
Companies.remove({ _id: req.params.company_id }, function(err) {
if (err) {
res.send(err);
}
else {
res.redirect('/companies');
}
});
});
};
HTML forms only support GET and POST. XMLHTTPRequest supports PUT and DELETE however, so you may have to go that route OR use something like method-override to allow HTML forms to submit using other HTTP verbs.
I have a get in my app.js
app.get('/api/personnel', api.personnel);
that calls this function as a callback to load some data from mongo:
exports.personnel = function(req, res) {
var docs;
db.personnel.find(function(err, docs) {
if (err) {
logError(err);
} else {
res.json({
personnel: docs
});
}
});
};
That works just fine, but I'd really like to be able to call a callback for testing purposes when the function is complete:
exports.personnel = function(req, res, callback) {
var docs;
db.personnel.find(function(err, docs) {
if (err) {
logError(err);
} else {
res.json({
personnel: docs
});
}
callback();
});
callback() is empty when the function is called from the live application and gives me a error:
Error: Can't set headers after they are sent.
How do I go about having a get call my callback?
You can just wrap that function to insert the additional function argument:
exports.personnel = function(req, res, callback) {
var docs;
db.personnel.find(function(err, docs) {
if (err) {
logError(err);
} else {
res.json({
personnel: docs
});
}
});
///////////////////////////////////////////////////
var callback = ...;
pp.get('/api/personnel', function(req, res) {
api.personnel(req, res, callback);
});
third arity in Express is always reserved for next() callback (as found in middlewares).
If you want to have "callback" but does not want to mess up with express, let's hack!
exports.personnel = function(req, res, callback) {
var docs;
db.personnel.find(function(err, docs) {
if (err) {
logError(err);
} else {
res.json({
personnel: docs
});
}
if(process.env.NODE_ENV === 'test')
callback();
});
then, when you want to test, export NODE_ENV=test in your shell