Some context
I've created a service worker to send notifications to registered users.
It works well until I tried to implement a sort of id to each people who register to a service worker (to send notification).
I do that because I have to delete old registration from my database, so I took the choice to let each users three registration (one for mobile device and two others for different navigator on computer) and if there is more, I want to remove from the database the older.
Tools
I'm using nodejs, express and mySql for the database.
The issue
When I launch a subscription I got this error:
SyntaxError: Unexpected token o in JSON at position 1
at JSON.parse (<anonymous>)
I saw in an other post that it's because they try to JSON.parse what's already an object.
But in my case, I can't find where I parse, see the part which are concerned:
// service.js (service worker file)
// saveSubscription saves the subscription to the backend
const saveSubscription = async (subscription, usrCode) => {
const SERVER_URL = 'https://mywebsite:4000/save-subscription'
subscription = JSON.stringify(subscription);
console.log(subscription); // I got here what I expect
console.log(usrCode); // <-------------------------------- HERE I GOT UNDEFIND
const response = await fetch(SERVER_URL, {
method: 'post',
headers: {
'Content-Type' : 'application/json',
},
body : {
subscription: subscription,
usrCode: usrCode
}
})
return response
}
But when I console.log(usrCode) in my inspector, I got the good value.
So how should I do to get the value in service.js
Maybe the problem is from:
const bodyParser = require('body-parser')
app.use(bodyParser.json())
At the beginning I thought that the issue is from the back (because I'm not really good with async function).
And here is the back, If maybe I got something wrong.
// index.js (backend)
// Insert into database
const saveToDatabase = async (subscription, usrCode) => {
// make to connection to the database.
pool.getConnection(function (err, connection) {
if (err) throw err; // not connected!
console.log(usrCode);
console.log(subscription);
connection.query(`INSERT INTO webpushsub (webpushsub_info, webpushsub_code) VALUES ('${subscription}', '${usrCode}')`, function (err, result, fields) {
// if any error while executing above query, throw error
if (err) throw err;
// if there is no error, you have the result
console.log(result);
connection.release();
});
});
}
// The new /save-subscription endpoint
app.post('/save-subscription', async (req, res) => {
const usrCode = req.body.usrCode; // <------------------ I'm not sure about this part
const subscription = req.body.subscription
await saveToDatabase(JSON.stringify(subscription, usrCode)) //Method to save the subscription to Database
res.json({ message: 'success' })
})
By searching on google, I've found this tutorial. So the reason why usrCode is undefined is because the service worker doesn't have access to a data stored in front.
First you have to pass it in the URL as following:
// swinstaller.js (front)
// SERVICE WORKER INITIALIZATION
const registerServiceWorker = async (usrCode) => {
const swRegistration = await navigator.serviceWorker.register('service.js?config=' + usrCode); //notice the file name
return swRegistration;
}
And then get it in the service worker:
// service.js (service worker file)
// get the usrCode
const usrCode = new URL(location).searchParams.get('config');
Related
i am trying to build an app and i am very new to all this. So I've built a very simple function to get data from firestore and it works fine from a moment. This is the code:
async getData(req, res) {
const dataRef = db.collection(`${req.body.banco}`)
let result = []
dataRef.onSnapshot(docSnapshot => {
docSnapshot.forEach(doc => {
const data = doc.data()
result.push(data)
})
console.log(result)
return res.status(200).send(result)
}, (error) => {
console.log(`Erro encontrado: ${error}`)
})
}
My problem is that when I try to update any field from the document. It gets updated but I end up receiving this error:
node:_http_outgoing:576
throw new ERR_HTTP_HEADERS_SENT('set');
^
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at new NodeError (node:internal/errors:372:5)
at ServerResponse.setHeader (node:_http_outgoing:576:11)
at ServerResponse.header (C:\Users\paulo\Desktop\sirius-back\functions\node_modules\express\lib\response.js:794:10)
at ServerResponse.send (C:\Users\paulo\Desktop\sirius-back\functions\node_modules\express\lib\response.js:174:12)
at ServerResponse.json (C:\Users\paulo\Desktop\sirius-back\functions\node_modules\express\lib\response.js:278:15)
at ServerResponse.send (C:\Users\paulo\Desktop\sirius-back\functions\node_modules\express\lib\response.js:162:21)
at C:\Users\paulo\Desktop\sirius-back\functions\src\controller\createDocs.js:70:40
at QueryWatch.onNext (C:\Users\paulo\Desktop\sirius-back\functions\node_modules\#google-cloud\firestore\build\src\reference.js:1914:13)
at QueryWatch.pushSnapshot (C:\Users\paulo\Desktop\sirius-back\functions\node_modules\#google-cloud\firestore\build\src\watch.js:469:18)
at QueryWatch.onData (C:\Users\paulo\Desktop\sirius-back\functions\node_modules\#google-cloud\firestore\build\src\watch.js:353:26) {
code: 'ERR_HTTP_HEADERS_SENT'
}
the app crashes and i have to start it over.
What is the reason of this? How can i get realtime updates from firestore databse after I update something from?
In Express you handle each requests by sending a single response to it. Since res a a response object, you can only send a response to the caller once. But since you're using onSnapshot, your code gets called for every change to the data too.
So initially, you load the data and send a response to the caller and all is 👍
But then when an update is made to the database, your code executes again and tries to send another response to the caller - and this is when you get an error.
The solution is to read the data only one with something like:
async getData(req, res) {
const dataRef = db.collection(`${req.body.banco}`)
let result = []
dataRef.get().then((docSnapshot) => {
docSnapshot.forEach((doc) => {
const data = doc.data()
result.push(data)
})
console.log(result)
return res.status(200).send(result)
}, (error) => {
console.log(`Erro encontrado: ${error}`)
})
}
Or a bit simplified:
async getData(req, res) {
const dataRef = db.collection(`${req.body.banco}`)
dataRef.get().then((docSnapshot) => {
const result = docSnapshot.docs.map((doc) => doc.data());
return res.status(200).send(result)
}, (error) => {
console.log(`Erro encontrado: ${error}`)
})
}
Once you've called res.send(...) the request is complete and the client stops listening. Sending further updates to a response is not possible with an Express request/response model like you're using.
Also see:
How to send multiple responses while computing in Express.js?
Sending multiple responses(res.json) with the same response object in Express.js
and more from searching for how to send multiple responses for a single request in express
You'll need to choose an infrastructure that allows a client to keep listening. Heads up: building something like that is quite involved, and you're likely better off if you use the client-side Firestore SDK to implement such realtime listeners
I am working on small backend project. I send GET requests via postman to express.js app. Express send request to mongoose and return data.
I am trying to make it shorter by writing req.query.data instead of object name.
req.query.data is object name which is imported to node file but mongoose "find" function read it as "req.query.data" instead of acuall data.
I tried putting req data in () but it still didn't want to read value. I have no idea how to make it working
Code:
const Daily = require("./DailyStats/DailySchema")
module.exports.GetData = async (req, res) => {
await Daily.find({"Date.month": 3}, function (err, data) {
if(err){
console.error(err)
}
res.send(data)
})
}
What I want is
await (req.query.data).find({"Date.month": 3}, function (err, data) {
if(err){
console.error(err)
}
res.send(data)
})
While using second code I got error "Cannot use method find on req.query.data"
find should be called on a mongoose.Model
You may use mongoose.model(req.query.data) assuming req.query.data is your model name
That said you should
check that provided data is only a valid model name
name data better, like modelName
const mongoose = require('mongoose')
mongoose.connect('mongodb://localhost:27017/dummy')
const NameModel = mongoose.model('Name', { name:String }, 'names')
;(async()=>{
try {
console.log(mongoose.model('Name') === NameModel) // true
} finally {
mongoose.disconnect()
}
})()
We are attempting to write a PostgreSQL Procedure to insert data into a table. We have created the procedure and ran said procedure with the variables below and it inserts just fine. However, when we try to use pg-promise with our express server, our string parameters are being read as unknown. When we iterate over the post body, we see that each parameter is reading as the type we expect to go in, and PostgreSQL is reading integer correctly, but it isn't reading string correctly. I've attempted to use the as.text function and it sends in the parameter value as "''" but that still reads as unknown. Is there something we are missing to successfully post the data?
let createInspection = async (req, res, next) => {
try {
let params = [];
for (let prop in req.body) {
console.log(typeof req.body[prop]);
params.push(req.body[prop]);
}
console.log(params)
let data = await db.proc('Inspections_Create', params);
res.status(200)
.json({
status: 'success',
data: data,
message: 'Inserted Inspection'
});
}
catch (error) {
return next(error);
}
}
I am using the following:
https://github.com/XeroAPI/xero-node
I am using a React app, talking to a Nodejs backend. The React app calls the node file connect.js as per the below:
// connect.js (node module)
const XeroClient = require('xero-node').XeroClient;
async function connect(req, res, next) {
try {
const xero = new XeroClient({
clientId: '9.............(hidden for SO)',
clientSecret: 'p...........(hidden for SO)',
redirectUris: [`http://localhost:3000/xeroCallback`],
scopes: 'openid profile email accounting.transactions offline_access'.split(" ")
});
let consentUrl = await xero.buildConsentUrl();
res.send(consentUrl);
} catch (err) {
console.log(err);
}
}
module.exports = connect;
This returns the URL to my React front end, which triggers a re-direct
This works fine, I am taking to the Xero Auth page, which then re-directs me back to localhost, where my React frontend calls on .callback.js from the back end, sending along the URL past from Xero:
{"http://localhost:3000/xeroCallback?code":"3......(hidden for SO)","scope":"openid profile email accounting.transactions","session_state":"E.........(hidden for SO)"}
Here is my code in callback.js
// callback.js (node module)
const { TokenSet } = require('openid-client');
const XeroClient = require('xero-node').XeroClient;
async function callback(req, res) {
const xero = new XeroClient({
clientId: '9.............(hidden for SO)',
clientSecret: 'p...........(hidden for SO)',
redirectUris: [`http://localhost:3000/xeroCallback`],
scopes: 'openid profile email accounting.transactions offline_access'.split(" ")
});
try {
await xero.initialize()
const TokenSet = await xero.apiCallback(req.body);
res.send(TokenSet);
} catch (err) {
console.log(err);
}
}
module.exports = callback;
There error is at "const TokenSet = await xero.apiCallback(req.body);" Gives me 'Access token undefined!"
So the error is because the Xero client has not yet been properly initialized.
https://github.com/XeroAPI/xero-node/blob/master/src/XeroClient.ts#L99
As you can see on the code below (linked above) the callbackParams function is a method on the openIdClient ( an oauth2.0 library ) - in order to fully setup they client you will need to call either xero.initialize() or xero.buildConsentUrl() It also looks like you should be passing back the req.url, though the req.body might still work..
this.openIdClient.callbackParams(callbackUrl)
It is setup this way to allow for more varied use cases for folks who do not need/want to access the helpers by requiring the openid-client.
// This needs to be called to setup relevant openid-client on the XeroClient
await xero.initialize()
// buildConsentUrl calls `await xero.initialize()` so if you wont
// need to also call initialize() if you are sending user through auth
await xero.buildConsentUrl()
// You can also refresh the token without needing to initialize the openid-client
// helpful for background processes where you want to limit any dependencies (lambda, etc)
await xero.refreshWithRefreshToken(client_id, client_secret, tokenSet.refresh_token)
https://github.com/XeroAPI/xero-node
Basically, the JSON object that's returned from a callback in my gRPC server is empty no matter what I do.
For the most part I'm following this tutorial, except I'm using a SQLite3 server instead of knex, and I've worked to the listProducts method. I haven't tried working on the other product methods yet.
In server.js I get some data from a SQLite3 database, and try to return it in a callback (at the bottom of the method). I also print out the data from the DB to confirm I'm actually getting valid data.
gRPC server.js
function listProducts(call, callback) {
console.log("******** Listed the products *********");
var data = "";
let db = new sqlite3.Database('../data/testDB.db', sqlite3.OPEN_READONLY, (err) => {
if(err){
console.error(err.message);
}
console.log("connected to DB");
});
db.serialize(() => {
db.get('SELECT NAME as name FROM PEEPS', (err, row) => {
if(err){
console.error(err.message);
}
console.log(row.name);
data.name = row.name;
});
});
db.close((err) => {
if(err) {
console.error(err.message);
}
console.log('closed db');
});
callback(null, { products: data.name });
}
Out put from gRPC server.js
******** Listed the products *********
connected to DB
Jeff // Correct data from DB.
closed db
The callback returns to client.js, where it was called. However, the object is always empty.
If I uncomment res.json({ name: "jessie" }); and comment res.json(result);, the code works as expected; name: jessie is sent to the browser as a JSON object.
So that tells me that from the client to the browser the data is being handled correctly. Therefore the problem is when the data is passed from the server.js to client.js.
gRPC client.js
// requirements
const path = require('path');
const protoLoader = require('#grpc/proto-loader');
const grpc = require('grpc');
// gRPC client
const productProtoPath = path.join(__dirname, '..', '..', 'protos', 'product.proto');
const productProtoDefinition = protoLoader.loadSync(productProtoPath);
const productPackageDefinition = grpc.loadPackageDefinition(productProtoDefinition).product;
const client = new productPackageDefinition.ProductService('localhost:50051', grpc.credentials.createInsecure());
// handlers
const listProducts = (req, res) => {
client.listProducts({}, (err, result) => {
console.log(result);
console.log(typeof result);
// console.log(res.json(result));
res.json(result);
// res.json({ name: "jessie" });
console.log("*******************");
});
};
Output from gRPC client.js
Server listing on port 3000
{} //Oh no! An empty JSON object!
object
*******************
Edit
Here is a link to my repository: https://github.com/burke212/grpc-node
The main problem here is that in your server code, your db methods are asynchronous but you are trying to access the result synchronously. You need to call the main callback for listProducts in the callback for db.get to ensure that you have the result of that database request before trying to use it. After making this change your listProducts method implementation should look more like this:
function listProducts(call, callback) {
let db = new sqlite3.Database('../data/testDB.db', sqlite3.OPEN_READONLY);
db.serialize(() => {
db.get('SELECT NAME as name FROM PEEPS', (err, row) => {
if(err){
console.error(err.message);
}
// Call the callback here to use the result of db.get
callback(null, { products: row.name });
});
});
db.close();
}
For simplicity I omitted the logging. Also, the sqlite3.Database constructor and db.close do not have callbacks in the example in the sqlite3 README. I suggest checking again whether those functions actually take callbacks.
In addition to that, now that you have shared the product.proto file that defines your service, there is another problem. The listProducts method in the ProductService service is declared as returning a ProductList object. In that message type, the products field must be an array of Product objects. All of the code in your method implementation is directed towards returning a string in that field, and that does not result in a compatible object.