I'm writing a server using NodeJS, Express and SQLite in order to provice RESTful services.
I want to create an endpoint for adding a new user to the database. The endpoint receives a POST request with the parameters username and password, and responds with the id of the newly created user.
According to the node-sqlite3 package documentation, when the run method succeeds, the this object inside the callback function contains the properties lastID and changes.
My problem is that, even though the run method succeeds and the new user is successfully inserted into the database, the this object is empty.
What am I doing wrong? How can I access this.lastID?
app.post('/users', (req, res) => {
const {
username,
password
} = req.body;
db.get(
`SELECT id
FROM Users
WHERE username = ?`,
[username],
(err, row) => {
if (err) {
console.error(err);
return res.sendStatus(500);
} else if (row) {
return res.status(400).send('Username already exist.');
}
db.run(
`INSERT INTO Users (username, password)
VALUES (?, ?)`,
[username, password],
(err) => {
if (err) {
console.error(err);
return res.sendStatus(500);
}
console.log(this); // prints {} to the console
res.send(this.lastID); // response body is empty
}
);
}
);
});
Try using an old-school function instead of an arrow function for your callback. I think with arrow functions this cannot be bound to a value.
Related
I am using PostgreSQL for the first time with an express server and am running into an error. On my register user route I am trying to check if the username or email already exists, because they need to be unique. What keeps happening is, say I pass in a username that is already in the database then the first return will run and return that the username is already in use. But what is happening is it is returning the username is already in use and it still running the rest of the code so it trying to return multiple json responses.
module.exports.register = async (req, res, next) => {
try {
const { username, email, password } = req.body;
postgres
.query("SELECT * FROM users WHERE username = $1", [username])
.then((data) => {
if (data.rows.length > 0) {
return res.status(409).json({
msg: "Username is already in use",
status: false,
});
}
})
.catch((err) => {
console.log(err);
});
postgres
.query("SELECT * FROM users WHERE email = $1", [email])
.then((data) => {
if (data.rows.length > 0) {
return res.status(409).json({
msg: "Email is already in use",
status: false,
});
}
})
.catch((err) => {
console.log(err);
});
const hashedPassword = await bcrypt.hash(password, 10);
postgres.query(
"INSERT INTO users (username, email, password) VALUES ($1,$2,$3) RETURNING *",
[username, email, hashedPassword],
(err, data) => {
if (err) {
console.log(err.stack);
} else {
return res.json({ user: data.rows, status: true });
}
}
);
} catch (err) {
next(err);
}
};
I can't figure out why the rest of the code is running even though I am returning res.json. If anybody has any suggestions/solutions I would really appreciate it!
The return in front of the res.status(409) is returning you out of the then of the postgres.query function instead of the full register function. As a result it jumps out of the then and runs the rest of the code from there, so it's still hashing the password and attempting an insert into the users table (which hopefully fails on a unique index).
In order to fix this you can either 1) Define a variable before the function, change it if something was found and then do a return outside of the then statement if the variable was changed 2) perform all the rest of the code in the then statement (since you're returning out of that it will not be run) or 3) use awaits instead and throw/next+return/res.json+return an the HTTP 409 error.
Option 3 will take the most effort but you should definitely learn to use this route as soon as possible as it makes writing async code a lot easier (plus you'll avoid getting a bunch of nasty nested then statement). You could try out using option 1 and 2 just to get a feel for how the flow of the express code works.
Hi I'm trying to read a users document stored on Firestore using Firebase Functions. Each user has a unique document with extra data that cannot be stored on Firebase Auth. The document name is the user UID.
But I can't access the doc when I'm trying to read it on my callable function.
Code to create doc when user is created:
exports.createdacc = functions.auth.user().onCreate(user => {
console.log('User created', user.phoneNumber);
return admin.firestore().collection('users').doc(user.uid).set({
number: user.phoneNumber,
verified: false,
});
});
Callable function to read that doc so I can make some decisions
exports.checkVerification = functions.https.onCall((data, context) => {
if (!context.auth){
throw new functions.https.HttpsError('unauthenticated');
}
console.log('user is ', context.auth.uid);
const user = admin.firestore().collection('users').doc(context.auth.uid);
user.get().then(doc => {
//temp code -- Not working
console.log('data read');
if (doc.get().verified){
console.log('verified');
} else {
console.log('not verified');
}
return "success";
}).catch(error => {
throw new functions.https.HttpsError('internal');
});
});
Why cant I read the doc? Nothing inside there executes.
Try to use data() at callback of user.get()
user.get().then(doc => {
//you get user doc value by using data()
const userData = doc.data();
// then you can use all properties from userData
const verified = userData.verified;
});
You don't return the promise returned by user.get().then(...);: your Cloud Function may be cleaned up before the asynchronous work is complete and the response sent back to the front-end.
Note that doing doc.get().verified is incorrect: as you will see in the doc, you need to pass the field path of a specific field to this method. So either you do doc.get("verified") or you can do doc.data().verified;.
Therefore the following should work:
exports.checkVerification = functions.https.onCall((data, context) => {
if (!context.auth) {
throw new functions.https.HttpsError('unauthenticated');
}
console.log('user is ', context.auth.uid);
const user = admin.firestore().collection('users').doc(context.auth.uid);
return user.get().then(doc => {
console.log('data read');
if (doc.get("verified") {
console.log('verified');
} else {
console.log('not verified');
}
return "success";
}).catch(error => {
throw new functions.https.HttpsError('internal');
});
});
In addition, note that you may throw an error if the user document does not exist and return a specific error to the front-end, i.e. not the generic internal one (maybe not-found, see the list of possible codes).
I have seen, on occasion, that information coming in to the function via context and data are actually JSON, and not strictly a standard Javascript object. In a similar issue of matching (in my case, a customClaim on the context.auth.token), I had to do something like:
JSON.parse(JSON.stringify(context.auth.token.customCLaim))
They behave like an object (i.e. I can call/assign context.auth.token.customClaim), but results from a console.log are different.
console.log(context.auth.token.customCLaim);
//prints {"userID": "1234567890"}
console.log(JSON.parse(JSON.stringify(context.auth.token.customClaim)));
//prints {userID: "1234567890"}
Subtle, but it tripped me up in a few authentication cases.
I am working with a NodeJS application which fetches film names and description from an Sqlite-3 file when user send a GET to /films. There seems to be a thing which I am missing while pushing the object to an array. I don't get what I am missing. The object does not get pushed to the array and always shows empty [] when I res.json() it back as response.
app.get('/films', (req, res) => {
let db = new sqlite3.Database('./data.db', sqlite3.OPEN_READWRITE, err => {
if (err) return console.error(err.message)
console.log('DB connected')
})
var films = []
db.serialize(() => {
db.each('select * from film', (err, row) => {
if (err) return console.log(err.message)
// console.log(row.name + '\t' + row.description)
films.push({
"name": row.name,
"description": row.description
})
})
})
res.json(films)
db.close(err => {
if (err) return console.error(err.message)
console.log('DB coonnection closed')
})
})
Your issue is that Express returns response object before the database retrieves any values. To fix this you’d normally move it inside the callback function.
In your case though db.each() method actually accepts 2 functions. The 1st one is callback which runs after each value is retrieved and wouldn’t be any help at all. The 2nd one is called complete in documentation and does exactly what you need.
Here’s the full reference in docs for db.each() from node-sqlite3 wiki.
With that you could write your code this way:
db.each(
'select * from film',
(err, row) => { /* Does normal stuff */ }),
(err, num) => { /* Sends response to client */
res.json(films);
console.log(`Retrieved ${num} films`); // (Just to show what the 2nd argument does)
}
);
Keep in mind that if your film database is not particularly huge docs actually recommend to use db.all method instead.
I am new to async/await and have set up a basic node.js server that handles form data for user registration. Below is my code
async.waterfall([async function(callback){ //Method 1
const hash = await bcrypt.hash(password, 10/*, () => { //breakpoint
console.log("Hash Generated Successfully");
}*/);
return hash;
}, function(hash, callback){ //Method 2
console.log(`The value of passed arg is: ${hash}`);
callback(null, 'success');
}], function(err, result){
if(err){
throw err
}
else {
console.log(result);
}
});
In Method 1, if i don't provide the callback to bcrypt.hash(), the code works correctly and the value of hash is printed. However, if i do provide the callback, i get this output:
The value of passed arg is: undefined.
So, i have two questions here.
1) Why does async.waterfall() break on providing callback to bcrypt.hash()?
2) What is the other way to do error handling, other than callbacks?
Passing the requisite parameters to the bcrypt callback function is a necessity if you plan on including the anonymous function as a parameter. For ex:
const hash = await bcrypt.hash(password, 10, (err, hash) => { // Added err, hash params.
console.log("Hash Generated Successfully");
});
return hash;
I am little bit confused with my code it's not worked synchronusly as it's should be. I use everyauth to do authentication.
registerUser(function(newUserAttrs) {
var login = newUserAttrs[this.loginKey()];
user.CreateNewUser(newUserAttrs.login, newUserAttrs.password, newUserAttrs.email, function(res, err) {
if(!err) {
return usersByLogin[login] = newUserAttrs;
}
else {
throw err;
}
});
})
in another file I have write this code
exports.CreateNewUser = function(login, pass, mail, callback) {
var sql = "insert into `user`(login,mail,pass) values(?,?,?)";
client.query(sql, [login, mail, pass], function(err, results, fields) {
if(!err) {
callback(results);
console.log('test')
}
else {
callback(results, err);
}
});
};
This code are working fine. I have tested him. the only problem is they are working synchronosly (as normal). Can someone explain me what thing I have done in wrong way that make it async. I want to get it done in sync way.
The current code give me error (it's make a entry in database and produce error on browser)
Error: Step registerUser of `password` is promising: userOrErrors ; however, the step returns nothing. Fix the step by returning the expected values OR by returning a Promise that promises said values.
at Object.exec (E:\proj\Node\node_modules\everyauth\lib\step.js:68:11)
at E:\proj\Node\node_modules\everyauth\lib\stepSequence.js:26:38
at [object Object].callback (E:\proj\Node\node_modules\everyauth\lib\promise.js:13:12)
at RouteTriggeredSequence._bind (E:\proj\Node\node_modules\everyauth\lib\stepSequence.js:25:20)
at RouteTriggeredSequence.start (E:\proj\Node\node_modules\everyauth\lib\stepSequence.js:52:33)
at RouteTriggeredSequence.routeHandler (E:\proj\Node\node_modules\everyauth\lib\routeTriggeredSequence.js:13:13)
at Object.<anonymous> (native)
at nextMiddleware (E:\proj\Node\node_modules\connect\lib\middleware\router.js:175:25)
at param (E:\proj\Node\node_modules\connect\lib\middleware\router.js:183:16)
at pass (E:\proj\Node\node_modules\connect\lib\middleware\router.js:191:10)
Thanks
The two pieces of code you present are asynchronous and not synchronous!
With everyauth, to be able to handle asynchronous user creation you should use a Promise. So your code will be something like :
registerUser(function(newUserAttrs) {
var promise = this.Promise();
var login = newUserAttrs[this.loginKey()];
user.CreateNewUser(newUserAttrs.login, newUserAttrs.password, newUserAttrs.email, function(res, err) {
if(!err) {
return promise.fulfill(newUserAttrs);
}
else {
promise.fulfill(user);
}
});
})
Without promise you couldn't be sure that your new user has been added in your database. But if it doesn't matter you could have something like that:
registerUser(function(newUserAttrs) {
var login = newUserAttrs[this.loginKey()];
user.CreateNewUser(newUserAttrs.login, newUserAttrs.password, newUserAttrs.email, function(res, err) {
if (err) console.log(err);
});
return newUserAttrs;
})
Because you are doing a database query, this code has to be asynchronous. The anonymous function you pass to client.query will not be called until the database query is complete, so your callback gets called asynchronously.
You will need to treat this all as asynchronous, so for instance you'll have to trigger some other callback instead of returning the user object/throwing.