Develop Reference

I'm unable to send a response to my react.js using http.get in node

I'm trying to get the temperature data from my node.js backend sent to react.js but i kept getting res.send is not a funtion
Sample code here
app.get("/gettemperature", (req, res) => {
const email = req.query.email;
let stmt = `SELECT * FROM users WHERE email=?`;
let todo = [email];
db.query(stmt, todo, (err, results, fields) => {
if (err) {
console.error(err.message);
}
if(results.length > 0 ){
let id = results[0].id;
let getID = `SELECT * FROM controlModules WHERE deviceowner=?`;
let getidData = [id];
db.query(getID, getidData, (err, resulta, fields) => {
if (err) {
console.error(err.message);
}
if(resulta.length > 0){
let lanip = resulta[0].ipaddress;
let url = "http://"+lanip+"/data";
http.get(url,(res) => {
let body = "";
res.on("data", (chunk) => {
body += chunk;
});
res.on("end", () => {
try {
let json = JSON.parse(body);
const temp_actual = json.temperature.value;
console.log(temp_actual);
res.setHeader('Content-Type', 'application/json');
res.end(
JSON.stringify({
value: temp_actual
})
);
} catch (error) {
console.error(error.message);
};
});
}).on("error", (error) => {
console.error(error.message);
});
}
});
}
});
});
i really need to return/send/respond the temperature data to my front end but i'm getting said error, is there a different way to return data?

It looks like you are mixing up an HTTP server you wrote in Node (although you haven't shown any relevant code) and an HTTP client you also wrote in Node.
res is an argument received by the callback you pass to http.get and contains data about the response received by your HTTP client.
Meanwhile, somewhere else (not shown) you have a different variable also called res which is the object your HTTP server uses to send its response to the browser running your React code.
You are calling res.send and wanting res to be the latter but it is really the former.
Since you haven't shown us the HTTP server code, it is hard to say where that res is, but there is a good chance you have shadowed it and can solve your problem by using different names (e.g. client_res and server_res).
That said. I strongly recommend avoiding using the http module directly as the API follows out of date design patterns and isn't very friendly. Consider using fetch or axios for making HTTP requests and Express.js for writing HTTP servers.

How to perform a POST request using background task for React Native apps using expo

I am trying to log my GPS coordinates in a React-Native expo application.
The background task runs successfully and consoles log the coordinates.
Now I want to send them to my server.
For example a post request to /api/mylocation?lon=123&lat=345
I tried a regular fetch method but I get a timeout error.
regular meaning fetch(url,{ method:'POST' etc}) (I know how to perform a basic fetch)
How can I solve this? I suspect it has to do with async and all that.
const LOCATION_TRACKING = 'location-tracking';
const startLocationTracking = async () => {
console.log('startLocationTracking');
await Location.startLocationUpdatesAsync(LOCATION_TRACKING, {
accuracy: Location.Accuracy.Highest,
timeInterval: 10000,
distanceInterval: 0,
});
const hasStarted = await Location.hasStartedLocationUpdatesAsync(
LOCATION_TRACKING
);
console.log('tracking started?', hasStarted);
};
TaskManager.defineTask(LOCATION_TRACKING, async ({ data, error }) => {
console.log('running task:', data, error);
// send_driver_location()
if (error) {
console.log('LOCATION_TRACKING task ERROR:', error);
return;
}
if (data) {
const { locations } = data;
let lat = locations[0].coords.latitude;
let long = locations[0].coords.longitude;
console.log(
`${new Date(Date.now()).toLocaleString()}: ${lat},${long}`
);
// add a fetch method here?
// fetch(url, {...}
}
});
Obviously, this will be helpful when I want to fetch tokens from my server for authentication purposes also.

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client ASYNC AWAIT not Working

I am trying to verify if some data is in the session. If not the controller will redirect you to another route, to get that data.
The problem is that I am getting an error "Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client"
I search over StackOverflow and I find that everyone that had this problem fix it using it async/await, but i was already using async await.
Your help will be trully appreciated!
Thank you very much!
Jose
dashboardCtrl.init = async (req, res) => {
//
var frontdata = req.session;
if (!frontdata.user) {
frontdata.user = await userfacebook.findOne({ where: { 'email': frontdata.passport.user } });
};
if (!frontdata.store) {
tmpstoredata = await userstore.findOne({ where: { 'userfacebookId': frontdata.user.id } });
if (!tmpstoredata) {
res.redirect('/toURL');
};
};
};
Note: I am using EJS MATE.
If i do this
dashboardCtrl.init = async (req, res) => {
//
res.redirect('/toURL');
};
Redirect works, the problem is using await. So i dont know how to continue

That error says that you have already sent an answer to the cliente. In other words, you are trying to declare for the second time -> **res.*****.
Check the flow again in case you have twice declared any action on express's "res".
The solution below allows you to have a good structured and readable asynchronous code.
dashboardCtrl.init = (req, res) => {
// I think destructuring looks good
let { user, store } = req.session;
(async () => {
try {
if (!user) user = await userfacebook.findOne({ where: { 'email': frontdata.passport.user } });
let tmpstoredata;
if (!store) tmpstoredata = await userstore.findOne({ where: { 'userfacebookId': frontdata.user.id } });
if (!tmpstoredata) res.redirect('/toURL');
} catch (err) {
// don't forget ;)
}
})()
};
Hope this can help you.
Greetings.

The code was OK
The problem was the EJS MATE
I replace it with EJS

Node.js / Koa: wait for API call before response

I have only basic JS knowledge (mainly jQuery), so this might be a really simple one.
And do realise performance-wise it might not be the best solution, but for now this is just proof of concept.
I have this simple Koa app. All I'm trying to do is to call an external API (Airtable) when the /callapi route is accessed and add some data from the API response to ctx.body.
However, I get a 404 Not Found when going to http://localhost:3000/callapi
I understand this is probably because the API call is asynchronous, so Node.js / Koa don't wait for it to finish and continue the execution, but there is no code setting the response body elsewhere, so it results in 404.
How can I achieve that?
Happy to use other routing middleware or additional middleware if needed.
I believe the Promises with async/await is the new way to go, which Koa embraces, so if I can somehow add / wrap this, it would be the best I guess.
const KoaRoute = require('koa-route');
const Koa = require('koa');
const app = new Koa();
var Airtable = require('airtable');
var base = new Airtable({apiKey: 'keyI6rZxwsXXXXXXX'}).base('appXXXXXX');
app.use(KoaRoute.get('/callapi', async function (ctx) {
await base('Couples').find('reclnxjiMeSljrzP0', function(err, record) {
console.log('Retrieved', record.id);
ctx.body = "Record ID from API: " + record.id;
});
}));
app.listen(3000);
console.log('listening on port 3000');

Looks like await is wrong. Please try this.
...
app.use(KoaRoute.get('/callapi', async function (ctx) {
/* please check return value if it returns correct value. */
try {
const record = await getBase();
console.log('Retrieved', record.id);
ctx.body = "Record ID from API: " + record.id;
} catch (err) {
// handle exception
}
}));
...
EDITED: Please add the following function and try again above thing.
function getBase() {
return new Promise((resolve, reject) => {
base('Couples').find('reclnxjiMeSljrzP0', function(err, record) {
console.log('Retrieved', record.id);
if (err) {
reject(err)
} else {
resolve(record);
}
});
});
}

Append a query param to a GET request?

I'm trying to make a simple API that calls another API that will return some information. The thing is, in order to connect to the second API, I need to attach query parameters to it.
So what I've tried to do so far is to use an axios.get in order to fetch the API. If I didn't need to add queries on top of that, then this would be really simple but I'm having a really hard time trying to figure out how to attach queries on top of my request.
I've created an object that pulled the original query from my end and then I used JSON.stringify in order to turn the object I made into a JSON. Then, from my understanding of Axios, you can attach params my separating the URL with a comma.
On line 6, I wasn't sure if variables would carry over but I definitely can't have the tag var turned into the string "tag", so that's why I left it with the curly brackets and the back ticks. If that's wrong, then please correct me as to how to do it properly.
the var tag is the name of the query that I extracted from my end. That tag is what needs to be transferred over to the Axios GET request.
app.get('/api/posts', async (req, res) => {
try {
const url = 'https://myurl.com/blah/blah';
let tag = req.query.tag;
objParam = {
tag: `${tag}`
};
jsonParam = JSON.stringify(objParam);
let response = await axios.get(url, jsonParam);
res.json(response);
} catch (err) {
res.send(err);
}
});
response is SUPPOSED to equal a JSON file that I'm making the request to.
What I'm actually getting is a Error 400, which makes me think that somehow, the URL that Axios is getting along with the params aren't lining up. (Is there a way to check where the Axios request is going to? If I could see what the actual url that axios is firing off too, then it could help me fix my problem)
Ideally, this is the flow that I want to achieve. Something is wrong with it but I'm not quite sure where the error is.
-> I make a request to MY api, using the query "science" for example
-> Through my API, Axios makes a GET request to:
https://myurl.com/blah/blah?tag=science
-> I get a response with the JSON from the GET request
-> my API displays the JSON file

After looking at Axios' README, it looks like the second argument needs the key params. You can try:
app.get('/api/posts', async (req, res, next) => {
try {
const url = 'https://myurl.com/blah/blah';
const options = {
params: { tag: req.query.tag }
};
const response = await axios.get(url, options);
res.json(response.data);
} catch (err) {
// Be sure to call next() if you aren't handling the error.
next(err);
}
});
If the above method does not work, you can look into query-string.
const querystring = require('query-string');
app.get('/api/posts', async (req, res, next) => {
try {
const url = 'https://myurl.com/blah/blah?' +
querystring.stringify({ tag: req.params.tag });
const response = await axios.get(url);
res.json(response.data);
} catch (err) {
next(err);
}
});
Responding to your comment, yes, you can combine multiple Axios responses. For example, if I am expecting an object literal to be my response.data, I can do:
const response1 = await axios.get(url1)
const response2 = await axios.get(url2)
const response3 = await axios.get(url3)
const combined = [
{ ...response1.data },
{ ...response2.data },
{ ...response3.data }
]