I am using Mongoose and Express/Node.js to build a simple api, but when I try to click on the "Read More" link (which uses Express routing parameters), I get "Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client". I understand that this happens when multiple responses are sent for a single post, but I can't for the life of me find where this is happening.
My code is below:
Post.find({}, function(err, foundPosts) {
res.render("home", {homeStartingContent: homeStartingContent, posts: foundPosts});
res.redirect("/");
});
})
app.get("/compose", function(req, res) {
res.render("compose");
})
app.post("/compose", function(req, res) {
const post = new Post({
title: req.body.title,
body: req.body.newPost,
teaser: req.body.newPost.substring(0,99) + "...",
});
// save the post and refresh home page to display most recent post
post.save(function(err) {
if(!err) {
res.redirect("/");
}
});
});
// express routing parameters; uses whatever comes after : to decide what to do
app.get("/posts/:postId", function(req, res) {
const requested = _.lowerCase(req.params.postId);
Posts.findOne({_id: requested}, function(err, post) {
res.render("post", {post: post});
});
});```
I'm pretty sure the issue is in the last app.get("/posts/:postID"...), but I can't figure it out.
I understand that this happens when multiple responses are sent for a single post
It also happens when you send more headers after already having sent a response. And that's what you do by calling first res.render and then res.redirect near the top of your code snippet. Also, this does not make sense, because the redirection will prevent the user from reading what you rendered before.
I've been trying to get the uber price estimates endpoint working, but I'm stuck on an error that leads me to a blank page saying, "Bad Request." The console also says "callback not a function" but I can't seem to find out what is wrong.
My route:
// Get an upfront fare before requesting a ride
app.get('/v1.2/estimates/price', function(request, response) {
// extract the query from the request URL
var query = request.query;
// if no query params sent, respond with Bad Request
if (!query || !query.lat || !query.lng) {
response.sendStatus(400);
} else {
uber.estimates.getPriceForRouteAsync( {
"product_id": "33de8094-3dc4-4ca9-8f67-243275f57623",
"start_latitude": "38.9597897",
"start_longitude": "-94.60699369999999",
"end_latitude": "39.010969",
"end_longitude": "-94.61509899999999"
})
.then(function(res) {
log(res);
})
.error(function(err) {
console.error(err);
});
}
});
Any help is appreciated.
Please check out the README for node-uber. The method does not take a JSON object but the arguments in the method call:
uber.estimates.getPriceForRouteAsync(38.9597897, -94.606994, 39.010969, -94.615098)
.then(function(res) { console.log(res); })
.error(function(err) { console.error(err); });
Also, the product ID is not needed as the /estimates/price endpoint returns an array of estimates for each product.
I have a node.js application with Express for routing and Mongoose for the database access.
I have this HTTP DELETE request that is deleting an entry in the database if certain requirements are met.
.delete(function (req, res) {
Movie.findOne({_id: req.params.id
}, function (err, movie) {
if (err)
res.send(err);
for (var i = 0, len = movie.actors.length; i < len; i++) {
if (movie.actors[i].actor == "Chuck Norris"){
res.status(403).send({ message: 'Cannot delete Chuck Norris' });
}
else {
Movie.remove({_id: req.params.id
}, function (err, movie) {
if (err)
res.send(err);
res.json({message: 'Movie deleted'});
});
}
}
});
});
If I send a HTTP DELETE with the ID of a film, it will check in the actors list if Chuck Norris is in the movie and I will prevent the deletion if he is there.
The problem is that my console is returning me this error :
Error: Can't set headers after they are sent.
So I presume that this an issue with my callbacks. Due to the asynchronus nature of node.js the "slow" database call made that my .delete sent the headers before the findOne finished ?
How can I manage to validate before deletion and send a proper http error code if the deletion is not possible ?
Be careful when you respond to a request multiple times in the same scope like that. On error you should prepend return to res.send(err) so that execution will not continue further. The same goes for your res.status() in the for-loop.
I am playing around with Nodejs and express by building a small rest API. My question is, what is the good practice/best way to set the code status, as well as the response data?
Let me explain with a little bit of code (I will not put the node and express code necessary to start the server, just the router methods that are concerned):
router.get('/users/:id', function(req, res, next) {
var user = users.getUserById(req.params.id);
res.json(user);
});
exports.getUserById = function(id) {
for (var i = 0; i < users.length; i++) {
if (users[i].id == id) return users[i];
}
};
The code below works perfectly, and when sending a request with Postman, I get the following result:
As you can see, the status shows 200, which is OK. But is this the best way to do this? Is there a case where I should have to set the status myself, as well as the returned JSON? Or is that always handled by express?
For example, I just made a quick test and slightly modified the get method above:
router.get('/users/:id', function(req, res, next) {
var user = users.getUserById(req.params.id);
if (user == null || user == 'undefined') {
res.status(404);
}
res.json(user);
});
As you can see, if the user is not found in the array, I will just set a status of 404.
Resources/advices to learn more about this topic are more than welcome.
Express API reference covers this case.
See status and send.
In short, you just have to call the status method before calling json or send:
res.status(500).send({ error: "boo:(" });
You could do it this way:
res.status(400).json(json_response);
This will set the HTTP status code to 400, it works even in express 4.
status of 200 will be the default when using res.send, res.json, etc.
You can set the status like res.status(500).json({ error: 'something is wrong' });
Often I'll do something like...
router.get('/something', function(req, res, next) {
// Some stuff here
if(err) {
res.status(500);
return next(err);
}
// More stuff here
});
Then have my error middleware send the response, and do anything else I need to do when there is an error.
Additionally: res.sendStatus(status) has been added as of version 4.9.0
http://expressjs.com/4x/api.html#res.sendStatus
A list of HTTP Status Codes
The good-practice regarding status response is to, predictably, send the proper HTTP status code depending on the error (4xx for client errors, 5xx for server errors), regarding the actual JSON response there's no "bible" but a good idea could be to send (again) the status and data as 2 different properties of the root object in a successful response (this way you are giving the client the chance to capture the status from the HTTP headers and the payload itself) and a 3rd property explaining the error in a human-understandable way in the case of an error.
Stripe's API behaves similarly in the real world.
i.e.
OK
200, {status: 200, data: [...]}
Error
400, {status: 400, data: null, message: "You must send foo and bar to baz..."}
I am using this in my Express.js application:
app.get('/', function (req, res) {
res.status(200).json({
message: 'Welcome to the project-name api'
});
});
The standard way to get full HttpResponse that includes following properties
body //contains your data
headers
ok
status
statusText
type
url
On backend, do this
router.post('/signup', (req, res, next) => {
// res object have its own statusMessage property so utilize this
res.statusText = 'Your have signed-up succesfully'
return res.status(200).send('You are doing a great job')
})
On Frontend e.g. in Angular, just do:
let url = `http://example.com/signup`
this.http.post(url, { profile: data }, {
observe: 'response' // remember to add this, you'll get pure HttpResponse
}).subscribe(response => {
console.log(response)
})
res.status(500).jsonp(dataRes);
try {
var data = {foo: "bar"};
res.json(JSON.stringify(data));
}
catch (e) {
res.status(500).json(JSON.stringify(e));
}
The best way of sending an error response would be return res.status(400).send({ message: 'An error has occurred' }).
Then, in your frontend you can catch it using something like this:
url: your_url,
method: 'POST',
headers: headers,
data: JSON.stringify(body),
})
.then((res) => {
console.log('success', res);
})
.catch((err) => {
err.response && err.response.data && this.setState({ apiResponse: err.response.data })
})
Just logging err won't work, as your sent message object resides in err.response.data.
Hope that helps!
You could do this
return res.status(201).json({
statusCode: req.statusCode,
method: req.method,
message: 'Question has been added'
});
FOR IIS
If you are using iisnode to run nodejs through IIS, keep in mind that IIS by default replaces any error message you send.
This means that if you send res.status(401).json({message: "Incorrect authorization token"}) You would get back You do not have permission to view this directory or page.
This behavior can be turned off by using adding the following code to your web.config file under <system.webServer> (source):
<httpErrors existingResponse="PassThrough" />
res.sendStatus(status) has been added as of version 4.9.0
you can use one of these res.sendStatus() || res.status() methods
below is difference in between res.sendStatus() || res.status()
res.sendStatus(200) // equivalent to res.status(200).send('OK')
res.sendStatus(403) // equivalent to res.status(403).send('Forbidden')
res.sendStatus(404) // equivalent to res.status(404).send('Not Found')
res.sendStatus(500) // equivalent to res.status(500).send('Internal Server Error')
I hope someone finds this helpful
thanks
I don't see anyone mentioned the fact that the order of method calls on res object is important.
I'm new to nodejs and didn't realize at first that res.json() does more than just setting the body of the response. It actually tries to infer the response status as well. So, if done like so:
res.json({"message": "Bad parameters"})
res.status(400)
The second line would be of no use, because based on the correctly built json express/nodejs will already infer the success status(200).
Hi i am developing nodejs application. I am inserting data to mongodb but my page always in 'loading' mode. But strange thing is my data inserted to mongodb immediately but page load not stopping. My code is shown below:
app.post('/Management/Post/New',function(req, res){
new Post({
title:req.body.post.title,
body:req.body.post.body,
keywords:req.body.post.keywords
}).save(function (err, docs){
if(err) {
return res.render(__dirname + "/views/createpost", {
title: 'Yeni Gönderi Oluştur',
stylesheet: 'postcreate',
error: 'Gönderi oluşturulurken bir hata ile karşılaşıldı'
});
}
console.log('Gönderi oluşturuldu');
});
});
Have no idea.
You only send a response when there is an error. If there's no error, you server never sends anything back: that's why the page seems to always be loading.
You need to send a response when you have no error, like this:
.save(function (err, docs){
if(err) { // Executed when there was an error with Mongo
return res.render(...);
} else { // Executed when everything is fine
return res.render(...);
}
});
You aren't handling the success scenario except for a console.log. You need a res.render() or res.redirect() on success, not just error