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Handling status 500 with try and catch

I can't tell what is the optimal way to handle the status 500 sent by my API. Could you please help me?
In the case below, when my API responds with a status 500, I wish to set an error message in my redux store. When my API sent a successful status code, I wish to "Fetch the user decks" in my store.
My first attempt felt logical and dry to me, but it did not work:
const createDeck = async () => {
try {
const request = await fetch(`${back}/deck/`, options)
const response = await request.json()
store.dispatch({ type: FETCH_USER_DECKS })
} catch (error) {
store.dispatch({ type: SET_ERROR, message: error })
}
}
When the API send a 500 status, no exception seems to be thrown and the code in my catch block is ignored.
My second and third attempt worked as I excepted them too, but they feel convoluted and weird:
2nd attempt:
const createDeck = async () => {
try {
const request = await fetch(`${back}/deck/`, options)
const response = await request.json()
if (request.status === 201 || request.status === 200) {
store.dispatch({ type: FETCH_USER_DECKS })
} else {
store.dispatch({ type: SET_ERROR, message: error })
}
} catch (error) {
console.log('error')
}
}
This works, but it ignores completely the catch block, making me wonder: what's even the point of try...catch then?
Third attempt:
const createDeck = async () => {
try {
const request = await fetch(`${back}/deck/`, options)
const response = await request.json()
if (request.status === 201 || request.status === 200) {
store.dispatch({ type: FETCH_USER_DECKS })
} else {
throw response
}
} catch (error) {
store.dispatch({ type: SET_ERROR, message: error })
}
}
This third attempt make use of catch, but it feels weird to manually throw an exception, to be immediately caught by catch.
Am I missing something here?

Isbn has properly answered this in the comments. I'm putting it here again for visibility:
"Since you're using fetch() it would probably make sense to adopt its implementation model and to not consider a 500 response as an exception (attempt 2). But I wouldn't see anything wrong with your third attempt either (axios, for example, would raise an error in that case). Note that fetch() response exposes a ok property to check whether the request succeeded or not"

Promise-wrapping http request cannot be ended [duplicate]

This question already has answers here:
nodejs - How to promisify http.request? reject got called two times
(6 answers)
Closed 1 year ago.
const http = require("http");
async function sendRequest(url) {
url = new URL(url);
const requestDetails = {
'hostname': url.hostname,
'port': url.port || 80,
'path': url.pathname,
'method': 'GET'
};
const req = await new Promise((resolve, reject) => {
const request = http.request(requestDetails, response => {
const status = response.statusCode;
if (status === 200 || status === 201) {
console.log("SUCCESS");
resolve(request);
} else {
console.log("ERROR");
reject(`Status code returned was ${status}`);
}
});
});
req.end();
}
sendRequest('http://httpbin.org/get');
It works when req.end() is inside the promise, but after passing the request out then execute req.end(), the console is just holding without any response. I tried to compare "req === request" by a middle variable, it returned true. Why doesn't moving end() out work? Shouldn't these two object the same?

The purpose of the req.end() is to finish the request. We might be cautious that if any body part is unsent or might in progress, it will flush them in the stream, or if any request is chunked, this will send to terminating.
I have implemented your same code in a bit different and cleaner way. Below way might help to reuse the same code for multiple apis.
const http = require("http");
/**
* #description call the http request
*/
async function doHttp(requestDetails){
return new Promise((resolve, reject)=>{
http.request(requestDetails, response => {
const status = response.statusCode;
response.setEncoding("utf-8");
if (status === 200 || status === 201) {
console.log("SUCCESS");
response.on('data', data => {
return resolve(data);
});
} else {
console.error("ERROR");
return reject(new Error("emptyData"));
}
}).on('error', (err) => {
// Catch the error if occured in request
console.error(`problem with request: ${e.message}`);
return reject(err);
}).end();
});
}
/**
* #description sending the request
*/
async function doSend(url) {
url = new URL(url);
const requestDetails = {
'hostname': url.hostname,
'port': url.port || 80,
'path': url.pathname,
'method': 'GET'
};
const data = await doHttp(requestDetails)
console.log(data);
}
doSend('http://httpbin.org/get');
At last, we could say req.end() is required to finish up any request. It completely depends on us, how we can implement a method.
An alternate solution might be this native https module is such as Axios, superagent, got, node-fetch. They provide a wrapper over the native nodejs code which might help us to control to handle an error and response.

You should move the request.end call inside the promise otherwise it just newer gets called because you will be waiting for a promise that is newer resolved because the request is not send.
Also you should reject the promise in case request object emits error event.

JS not waiting for Promise to be fulfilled?

I'm trying for my application to wait for the promise to return before executing other code, which is dependant on that data. For this I am using then(), but it is not working as expected, as the next code is still being executed, before my values are being returned.
I am using Express to handle requests and Axios to make my own requests.
index.js:
app.get('/api/guild/:serverId', async (req,res) => {
bot.getGuild(req.params.serverId).then((response) => { // It should here wait for the promise before executing res.send(...)...
res.send(response.data);
}).catch((error) => {
console.log(error) // Error: Returns that response is undefined
});
});
bot.js:
module.exports.getGuild = async function (id){
axios.get(BASE_URL + `guilds/${id}`, {
headers: {
'Authorization' : 'Bot ' + token // Send authorization header
}
}).then(function (response){ // Wait for response
console.log("Returning guild data")
return response; // Sending the response and also logging
}).catch(function (error){
console.log("Returning undefined.")
return undefined; // This is not being used in my problem
});
}
I already know that getGuild(id) is returning a working response. It also logs Returning guild data when returning the data. Yet this is being returned after index.js returning the error, that the response is undefined. Even though it should actually wait for the Promise to be fulfilled and then working with response.data.
Log:
TypeError: Cannot read property 'data' of undefined
at bot.getGuild.then (...\website\src\server\index.js:47:27)
at process._tickCallback (internal/process/next_tick.js:68:7)
Returning guild data

then is not needed in async functions because await is syntactic sugar for then.
getGuild doesn't return a promise from Axios, so it cannot be chained.
It should be:
module.exports.getGuild = function (id){
return axios.get(BASE_URL + `guilds/${id}`, {
...
The use of catch in getGuild is a bad practice because it suppresses an error and prevents it from being handled in caller function.

The getGuild function must wait for the axios promise in order to return a result:
try {
let res = await axios.get(BASE_URL + `guilds/${id}`, {
headers: {
'Authorization': 'Bot ' + token // Send authorization header
}
})
console.log("Returning guild data")
return res
} catch (exp) {
console.log("Returning undefined.")
return undefined;
}

Can I throw error in axios post based on response status

Is it possible to throw an error on purpose inside the .then() block in axios? For instance, if the api responds with 204 status code, could I throw an error and run the catch block?
For example:
axios.post('link-to-my-post-service', {
json-input
}).then(response => {
if (response.status === 200) {
//proceed...
}
else {
// throw error and go to catch block
}
}).catch(error => {
//run this code always when status!==200
});
EDIT
I tried this, but it didn't work:
var instance = axios.create({
validateStatus: function (status)
{
return status == 200;
}
});
axios.post('link-to-my-post-service', {input: myInput}, instance)
.then(response => {
dispatch({
type: "FETCH_SUCCESS",
payload: response.data
});
}).catch(error => {
dispatch({
type: "FETCH_FAILED",
payload: error
});
});
When I get a status code 204, still the executed block is then() block instead of the catch block.
EDIT 2
The correct answer using Ilario's suggestion is this:
var instance = axios.create({
validateStatus: function (status)
{
return status == 200;
}
});
instance.post('link-to-my-post-service', {input: myInput})
.then(response => {
dispatch({
type: "FETCH_SUCCESS",
payload: response.data
});
}).catch(error => {
dispatch({
type: "FETCH_FAILED",
payload: error
});
});
Now when the status code is not equal to 200 the catch block code is executed.

If you give a look at the GitHub Project Page you will notice following option description.
/* `validateStatus` defines whether to resolve or reject the promise for a given
* HTTP response status code. If `validateStatus` returns `true` (or is set to `null`
* or `undefined`), the promise will be resolved; otherwise, the promise will be
*/ rejected.
validateStatus: function (status) {
return status >= 200 && status < 300; // default
},
So you could create an Instance with your own configuration.
var instance = axios.create({
validateStatus: function (status) {
return status == 200;
},
});
You could also set defaults. These will be applied to every request.
axios.defaults.validateStatus = () => {
return status == 200;
};
UPDATE 1
To set the config only on a specific operation you could replace "config" with your desired values or methods.
axios.post(url[, data[, config]])
UPDATE 2
I tried this, but it didn't work.
You cannot pass the instance to axios.post(). You must call post on the new instance.
var instance = axios.create({
validateStatus: function (status) {
return status == 200;
}
});
instance.post('url', data, config);

Thank you very much for your suggestions. The answer was simpler than I expected.
I didn't want to set any default options to change the behavior of axios, so I just tried something like the code below, and it worked. Every time the code throw new Error("Error"); is executed, the catch block code is executed after that.
axios.post('link-to-my-post-service', {
json-input
}).then(response => {
if (response.status === 200) {
//proceed...
}
else {
// throw error and go to catch block
throw new Error("Error");
}
}).catch(error => {
//when throw "Error" is executed it runs the catch block code
console.log(error)
});

Promise returns undefined

I know you can't make an asynchronous function behave synchronously but
how do I add some kind of order to my promises chain?
One result relies on the previous promise value and when that doesn't happen I get an undefined error. It's an http request so it is relying on external factors like how fast my connection can execute the request, etc.
module.exports.movieCheck = function(authToken) {
return request({
method : 'GET',
uri : 'https://graph.facebook.com/' + profileID + '/posts?fields=message&limit=25&' + authToken
}).spread(function (response, body) {
console.log('https://graph.facebook.com/' + profileID + '/posts?fields=message&limit=25&' + authToken);
return body;
}, function(e) {
console.log(e);
});
};
I am calling the above method as follows. However console.log returns undefined.
movieCheck.getToken()
.then(function(token) {
movieCheck.movieCheck(token);
})
.then(function(movies) {
console.log(movies); //should print json data
});
Terminal prints
undefined
https://graph.facebook.com/.../posts?fields=message&limit=25&access_token=....

Try to return the promise from the first then callback
movieCheck.getToken()
.then(function (token) {
return movieCheck.movieCheck(token);
}).then(function (movies) {
console.log(movies); //should print json data
});