Error: Can't set headers after they are sent nodejs - node.js

Question

When I post the new event, it is created and the sort function works properly as well but when I call the search function, I want it to compare it with both name and location but it doesn't compare with location. Is there any way to check both? Also after sorting or search when I want to create a new event, it gives me the below error. I am new to this. Help me with both the errors.
server.js
var express= require('express');
var bodyParser= require('body-parser');
var morgan = require('morgan');
var config=require('./config');
var app= express();
var mongoose=require('mongoose');
var lodash= require('lodash');
var underscore= require('underscore');
//var User=require('./database/user')
mongoose.connect('mongodb://localhost:27017/db',function(err){
if(err){
console.log(err);
}
else{
console.log("connected!");
}
});
//res.json({message:" " })
app.use(bodyParser.urlencoded({extended: true })); //if false then parse only strings
app.use(bodyParser.json());
app.use(morgan('dev'));//log all the requests to the console
var api=require('./app/routes/api')(app,express,underscore,lodash);
app.use('/api',api);
app.get('*',function(req,res){
// res.sendFile(__dirname + '/public/views/index.html');
}); // * means any route
app.listen(config.port,function(err){
if(err){
console.log(err);
}
else{
console.log("The server is running");
}
});
api.js
var User= require('../models/user');
var Event=require('../models/event');
var config=require('../../config');
var secret=config.secretKey;
module.exports=function(app,express,underscore,lodash) {
var api = express.Router();
// app.use()
api.post('/signup', function (req, res) {
var user = new User({
name: req.body.name,
username: req.body.username,
password: req.body.password
});
user.save(function (err) {
if (err) {
res.send(err);
return;
}
res.json({
message: 'User created!'
});
});
});
api.get('/users', function (req, res) {
User.find({}, function (err, users) {
if (err) {
res.send(err);
return;
}
res.json(users);
});
});
/* api.get('search',function(req,res){
search: req.body.search;
if(search==)
});*/
api.post('/eventfeed', function (req, res) {
var event = new Event({
name: req.body.name,
location: req.body.location,
description: req.body.description,
price: req.body.price,
rating: req.body.rating
});
event.save(function (err) {
if (err) {
res.send(err);
return;
}
res.json({
message: 'Event created!'
});
});
});
api.get('/event', function (req, res) {
Event.find({}, function (err, event) {
if (err) {
res.send(err);
return;
}
res.json(event);
});
});
api.get('/sortby_price', function (req, res) {
Event.find({}, function (err, events) {
if (err) {
res.send(err);
return;
}
var ascending = true;//change to false for descending
events.sort(function (a, b) {
return (a.price - b.price) * (ascending ? 1 : -1);
});
res.json(events);
});
});
api.get('/sortby_rating', function (req, res){
Event.find({}, function (err, events) {
if (err) {
res.send(err);
return;
}
var ascending = true;//change to false for descending
events.sort(function (a, b) {
return (a.rating - b.rating) * (ascending ? 1 : -1);
});
res.json(events);
});
});
api.post('/search', function (req, res) {
Event.find({'name':req.body.name},function (err, events) {
if (err)
return res.json(err);
else
res.json(events);
});
Event.find({'location':req.body.name},function (err, events) {
if (err)
return res.json(err);
else
res.json(events);
console.log("name is" + req.body.name);
});
});
return api;
}
error
http_outgoing.js:335
throw new Error('Can\'t set headers after they are sent.');
^
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:335:11)
at ServerResponse.header (c:\Users\MY LAPY\WebstormProjects\Main\node_modules\express\lib\response.js:718:10)
at ServerResponse.send (c:\Users\MY LAPY\WebstormProjects\Main\node_modules\express\lib\response.js:163:12)
at ServerResponse.json (c:\Users\MY LAPY\WebstormProjects\Main\node_modules\express\lib\response.js:249:15)
at Query.<anonymous> (c:\Users\MY LAPY\WebstormProjects\Main\app\routes\api.js:209:25)
at c:\Users\MY LAPY\WebstormProjects\Main\node_modules\mongoose\node_modules\kareem\index.js:177:19
at c:\Users\MY LAPY\WebstormProjects\Main\node_modules\mongoose\node_modules\kareem\index.js:109:16
at process._tickCallback (node.js:355:11)

Answer 1

In your /api/search route, you are performing two Event.find()s in parallel and inside the callback for each of those, you're responding to the same http request.
So you need to either:
Have a third callback that is called only when both Event.find()s have completed, so you respond to the request only once there, OR
Perform the Event.find()s sequentially by placing one inside the callback of the other and only respond to the request inside the inner-most callback, OR
Only perform one Event.find() by using $or to check either field. For example:
api.post('/search', function (req, res) {
Event.find({
$or: [ {'name': req.body.name}, {'location': req.body.name} ]
}, function (err, events) {
if (err)
return res.json(err);
else
res.json(events);
});
});