Good morning!
I've been struggling to get a specific value returned from my function:
const getFolders = function (PID){
var token = getStoredToken()
request.get({
url: 'https://api.procore.com/vapid/folders',
headers: {
Authorization: "Bearer " + token.access_token
},
json: {
company_id: '12594',
project_id: PID
}
}, function test(err, response, body){
return body
})
// I NEED THE RETURN VALUE OF THE ABOVE FUNCTION HERE SO I CAN ACCESS WHEN CALLING getFolders()
}
Is this possible? If so, how?
Thanks!
Usually there will be three ways dealing with asynchronous stuff:
callback
promise
async/await
callback:
const getFolders = function(PID, callback) {
var token = getStoredToken()
request.get({
url: 'https://api.procore.com/vapid/folders',
headers: {
Authorization: "Bearer " + token.access_token
},
json: {
company_id: '12594',
project_id: PID
}
}, function(err, response, body) {
callback(body)
})
}
getFolders(pid, (v) => {
console.log(v)
})
promise:
const getFolders = function(PID, callback) {
return new Promise((resolve, reject) => {
var token = getStoredToken()
request.get({
url: 'https://api.procore.com/vapid/folders',
headers: {
Authorization: "Bearer " + token.access_token
},
json: {
company_id: '12594',
project_id: PID
}
}, function(err, response, body) {
if (err) {
return reject(err)
}
resolve(body)
})
})
}
getFolders(pid)
.then(v => {
console.log(v)
}).catch(error => {
console.error(error)
})
async/await:
Due to async/await is actually a syntax sugar, the getFolders function is the same as using promise's, the difference is when you call it:
(async function() {
try {
let v = await getFolders(pid)
console.log(v)
} catch(e) {
console.error(e)
}
})()
Not sure if this solve your confusion.
The way you are expecting is wrong, the test function which you have passed to request.get method is a callback function which will execute in asychronous manner , it means whenever your API responds from the server, that callback function will get execute.
So before that you are expecting the response (body) below the request method, which is wrong.
In this case you just have to write some other function to call this get method and in callback function you can easily access that response or just write your code in that test function itself.
like below - :
request.get({
url: 'https://api.procore.com/vapid/folders',
headers: {
Authorization: "Bearer " + token.access_token
},
json: {
company_id: '12594',
project_id: PID
}
}, function test(err, response, body){
// instead of returning body
// use the body here only
let result = body;
// your code here
})
Or the other way -:
const getFolders = function (PID){
var token = getStoredToken();
this.get(function(err, response, body){
// do whatever you want with the response now
updateFolder()
})
}
function get(callback){
request.get({
url: 'https://api.procore.com/vapid/folders',
headers: {
Authorization: "Bearer " + token.access_token
},
json: {
company_id: '12594',
project_id: PID
}
}, callback)
}
Related
I am new to NodeJS and I am working on a request.get problem. My goal is simply have a function that request the web, and when request finished, the function returns the result, otherwise it returns an error message.
Here's the function that I used for request:
var artistNameIdMap = {};
var getPopularArtists = async () => {
//https://nodejs.org/api/http.html#http_http_request_options_callback
var options = {
url: CONSTANTS.API_ENDPOINTS.playlist_endpoint + subpath,
headers: { 'Authorization': 'Bearer ' + access_token,
'Accept': 'application/json',
'Content-Type': 'application/json'},
json: true
}
request.get(options, function(error, response, body) {
if (response.statusCode === 200){
console.log("inside");
artistNameIdMap = getArtistNameIdMap(body, artistNameIdMap);
} else {
res.send("get popular error");
return {};
}
})
console.log("outside");
return artistNameIdMap;
module.exports = {
GetPopularArtists: getPopularArtists
}
And this function is included in a getPopular.js file. I would like to call the function in another file playlist.js.
In playlist.js, I wrote
const getPopular = require('./controllers/getPopular');
router.get("/BPM/:BPM", (req, res) =>{
const artistNameIdMap = getPopular.GetPopularArtists();
console.log(artistNameIdMap);
let BPM = req.params.BPM;
res.send(BPM);
})
However the result I got is
outside
Promise { {} }
inside
It seems like the return was before the request gives back the information. I wonder what should I write to make sure that I can obtain the correct artistNameIdMap at playlist.js.
Though you've already accepted an answer, there are a couple of additional things I can add. First, the request() library has been deprecated and it is not recommended for new code. Second, there is a list of recommended alternatives here. Third, all these alternatives support promises natively as that is the preferred way to program asynchronous code in modern nodejs programming.
My favorite alternative is got() because I find it's interface simple and clean to use and it has the features I need. Here's how much simpler your code would be using got():
const got = require('got');
let artistNameIdMap = {};
async function getPopularArtists() {
const options = {
headers: { 'Authorization': 'Bearer ' + access_token,
'Accept': 'application/json',
'Content-Type': 'application/json'},
};
const url = CONSTANTS.API_ENDPOINTS.playlist_endpoint + subpath;
let results = await got(url, options).json();
// update local cache object
artistNameIdMap = getArtistNameIdMap(results, artistNameIdMap);
return artistNameIdMap;
}
module.exports = {
GetPopularArtists: getPopularArtists
}
Note: The caller should supply error handling based on the returned promise.
GetPopularArtists().then(results => {
console.log(results);
}).catch(err => {
console.log(err);
});
Since you want to use Promises, use it like this
const getPopularArtists = () => new Promise((resolve, reject) {
const options = {
url: CONSTANTS.API_ENDPOINTS.playlist_endpoint + subpath,
headers: {
'Authorization': 'Bearer ' + access_token,
'Accept': 'application/json',
'Content-Type': 'application/json'
},
json: true
}
request.get(options, (error, response, body) => {
if (error) {
reject(error);
} else if (response.statusCode === 200) {
console.log("inside");
resolve(getArtistNameIdMap(body, artistNameIdMap));
} else {
reject("get popular error");
}
});
});
module.exports = {
GetPopularArtists: getPopularArtists
}
And use it like
const getPopular = require('./controllers/getPopular');
router.get("/BPM/:BPM", async (req, res) =>{
try {
const artistNameIdMap = await getPopular.GetPopularArtists();
console.log(artistNameIdMap);
let BPM = req.params.BPM;
res.send(BPM);
} catch(err) {
res.send(err);
}
})
Alternatively, without promises, you'll need to use a callback
Using callbacks:
const getPopularArtists = (callback) => {
const options = {
url: CONSTANTS.API_ENDPOINTS.playlist_endpoint + subpath,
headers: { 'Authorization': 'Bearer ' + access_token,
'Accept': 'application/json',
'Content-Type': 'application/json'},
json: true
}
request.get(options, function(error, response, body) {
if (error) {
callback(error);
} else if (response.statusCode === 200){
console.log("inside");
callback(null, getArtistNameIdMap(body, artistNameIdMap));
} else {
callback("get popular error");
}
})
};
module.exports = {
GetPopularArtists: getPopularArtists
}
And use it like:
const getPopular = require('./controllers/getPopular');
router.get("/BPM/:BPM", (req, res) =>{
getPopular.GetPopularArtists((err, artistNameIdMap) => {
if (err) {
// handle error here
} else {
console.log(artistNameIdMap);
let BPM = req.params.BPM;
res.send(BPM);
}
});
});
i have this asynchronous function
//example get
async getDatafromAPINODE(url) {
try {
let respond = await axios.get(API_URL_NODE + url, {
headers: {
"Content-Type": "application/json",
Authorization: "Bearer " + this.state.tokenUser,
},
});
if (respond.status >= 200 && respond.status < 300) {
console.log("respond Post Data", respond);
}
return respond;
} catch (err) {
let respond = err;
console.log("respond Post Data err", err);
return respond;
}
}
how can i make this function export-able ? so i can use in another file with import
ok this what im doing
//asyncFunction.js
export const getDatafromAPINODE = async (url, props) => {
try {
let respond = await axios.get(API_URL_NODE + url, {
headers: {
"Content-Type": "application/json",
Authorization: "Bearer " + props,
},
});
if (respond.status >= 200 && respond.status < 300) {
console.log("respond Post Data", respond);
}
return respond;
} catch (err) {
let respond = err;
console.log("respond Post Data err", err);
return respond;
}
};
then i called using
import {getDatafromAPINODE} from '../../../helper/asyncFunction'
as you can see im using 2 args url and props, the props will be used for getting the token for my need
I'm using the nodejs serverless module to create a lambda aws function.
'use strict';
const request = require('request');
const options = {
url: 'https://api.mysportsfeeds.com/v2.0/pull/nfl/2018-regular/games.json',
method: 'GET',
headers: {
"Authorization": "Basic " + Buffer.from("1da103"
+ ":" + "MYSPORTSFEEDS").toString('base64')
}
}
//this is automatically called by aws
module.exports.hello = async (event, context) => {
let result;
request.get(options, (error, response, body) => {
result = JSON.parse(body).lastUpdatedOn; //never happens cuz of async
});
return {
statusCode: 200,
body: JSON.stringify({
message: 'Go Serverless v1.0! Your function executed successfully!',
input: result,
}),
};
};
The problem I'm having is that I can't return output from the get request, because the assignment to the result variable (in the async get request) happens after the return statement. I don't think I can turn the outer function into a callback function for the get request. How could I work around this?
An alternative could be to extract the request logic and put it into a new function.
Remember, you need to catch any errors, so use a try-catch block for doing that.
'use strict';
const request = require('request');
const options = {
url: 'https://api.mysportsfeeds.com/v2.0/pull/nfl/2018-regular/games.json',
method: 'GET',
headers: {
"Authorization": "Basic " + Buffer.from("1da103"
+ ":" + "MYSPORTSFEEDS").toString('base64')
}
};
function getResult() {
return new Promise(function (resolve, reject) {
request.get(options, (error, response, body) => {
if (error) return reject(error);
resolve(JSON.parse(body).lastUpdatedOn); //never happens cuz of async
});
});
}
//this is automatically called by aws
module.exports.hello = async (event, context) => {
let result = await getResult();
return {
statusCode: 200,
body: JSON.stringify({
message: 'Go Serverless v1.0! Your function executed successfully!',
input: result,
}),
};
};
I have a NodeJS application and I think I have an issue with returning from inside a nested Promise.
As below, the getToken function is working. It calls another function to retrieve a password. After this, it uses the password value when making a GET call.
We then successfully get a token and we print the body to the console. This works.
However, I now have the challenge of passing the value of body which is my token, to another method for later consumption. printBodyValue currently fails and fails with an 'undefined' error.
How can I pass the value from deep inside getToken to printBodyValue
getToken: function() {
module.exports.readCredentialPassword()
.then(result => {
var request = require('request-promise');
var passwd = result;
var basicAuthData = "Basic " + (new Buffer("fooUser" + ":" + passwd).toString("base64"));
var options = {
method: "GET",
uri: ("http://localhost:8001/service/verify"),
followRedirects: true,
headers: {
"Authorization": basicAuthData
}
};
return request(options)
.then(function (body) {
console.log("Token value is: ", body);
return body;
})
.catch(function (err) {
console.log("Oops! ", err);
});
});
}
printBodyValue: function() {
module.exports.getToken().then(function(body) {
console.log("Token value from printBodyValue is: \n", body);
});
}
In getToken, instead of using the nested promise anti-pattern, chain your promises instead, and return the final promise, so that you can then consume the promise and use its resolved value:
(also, since you're using ES6, prefer const over var)
getToken: function() {
return module.exports.readCredentialPassword()
.then(result => {
const request = require('request-promise');
const passwd = result;
const basicAuthData = "Basic " + (new Buffer("fooUser" + ":" + passwd).toString("base64"));
module.exports.log("Sending Request: ", jenkinsCrumbURL);
const options = {
method: "GET",
uri: ("http://localhost:8001/service/verify"),
followRedirects: true,
headers: {
"Authorization": basicAuthData
}
};
return request(options);
})
.then(function(body) {
console.log("Token value is: ", body);
// the return value below
// will be the final result of the resolution of
// `module.exports.readCredentialPassword`, barring errors:
return body;
})
.catch(function(err) {
console.log("Oops! ", err);
});
}
printBodyValue: function() {
module.exports.getToken().then(function(body) {
console.log("Token value from printBodyValue is: \n", body);
});
}
I have a method called fetchMerchantData which calls 3 other async methods. I'm trying to use Promise so that it doesn't call resp.direct(301, ...) until all the requests are finished but it's not working.
function fetchOauth2Token(authorizationCode, resp) {
...
request({
url: `https://connect.squareup.com/oauth2/token`,
method: "POST",
json: true,
headers: oauthRequestHeaders,
form: oauthRequestBody,
}, (error, oauthResp, body) => {
if (body.access_token) {
Promise.resolve(fetchMerchantData(body.access_token, body.merchant_id)).then(() => {
console.log("last!"); //<--------------------- this is printing first
resp.redirect(
301,
`myurl.com/blah`
);
});
;
} else {
// TODO find out what to do on failure
resp.redirect(301, `myurl.com/?error=true`);
}
})
}
function fetchMerchantData(access_token, merchant_id){
const updates = {};
request({
url: `https://connect.squareup.com/v1/me/locations`,
method: "GET",
json: true,
headers: {
Authorization: `Bearer ${access_token}`,
Accept: 'application/json',
"Content-Type": "application/json",
},
}, (error, response) => {
if (!error) {
const locations = response.body;
Promise.all([
saveMerchant(merchant_id, access_token, locations),
saveLocations(merchant_id, locations),
installWebhookForLocations(access_token, locations),
]).then(values => {
console.log("first!"); //<--------------------- this is printing last
return Promise.resolve("Success");
})
}
});
}
And here's an example of the saveMerchant method which calls firebase:
function saveMerchant(merchant_id, access_token, locations) {
const merchantRef = database.ref('merchants').child(merchant_id);
const location_ids = locations.map(location => location.id);
merchantRef.update({
access_token,
location_ids,
});
}
How would I synchronize this?
== UPDATE ==
This is how my installWebhookForLocations method looks:
function installWebhookForLocations(access_token, locations){
const locationIds = locations.map(location => location.id);
locationIds.forEach((locationId) => {
request({
url: `https://connect.squareup.com/v1/${locationId}/webhooks`,
method: "PUT",
json: true,
headers: {
Authorization: `Bearer ${access_token}`,
Accept: 'application/json',
"Content-Type": "application/json",
},
body: ["PAYMENT_UPDATED"],
}, (error) => {
if (!error){
console.log(`Webhook installed for ${locationId}`);
}
});
});
}
Here is an example of saveMerchant that would use a promise.
function saveMerchant(merchant_id, access_token, locations) {
return new Promise(function (resolve, reject) {
const merchantRef = database.ref('merchants').child(merchant_id);
const location_ids = locations.map(location => location.id);
merchantRef.update({
access_token,
location_ids,
}, function (error) {
if (error) return reject(error);
resolve();
});
});
}
To make the above easier, there is a nice Promise library called Bluebird, it has a promisify utility, that you could apply to firebird update method.
Also for your second question were your using forEach, bluebird has a nice utility function called map that you could use instead.