I am trying to send the response when the loop k value is equal to users[0].employees.length, but it's directly moving forward to max length, how do I solve it
Userlist.find(queryObj).exec(function (err, users) {
if (err) {
return res.status(400).send({
message: errorHandler.getErrorMessage(err)
});
}
else {
console.log('found users list', users);
// res.json(users[0].employees);
var k=0;
var resparr=[]
for(var i=0;i<users[0].employees.length;i++){
k++;
User.find({"_id":users[0].employees[i]._id}).exec(function(err,user){
resparr=resparr.concat(user);
console.log("resparray:",k,resparr.length,i,users[0].employees.length)
if(k==users[0].employees.length)
{
console.log("success",resparr)
res.json(resparr);
}
})
}
}
});
You are using an asynchronous function call within a synchronous loop. The loop will always finish before your callback functions are called.
You will need some kind of asynchronous looping. For a native solution you can use Promises:
const getUser = (id) => {
return new Promise((resolve, reject) => {
User.find({ '_id': id })
.exec((err, user) => {
if (err) reject(err);
else resolve(user);
});
});
};
const promises = users[0].employees.map(({ _id: id }) => getUser(id));
Promise.all(promises)
.then(users => res.json(users))
.catch(err);
For utility packages in node.js, I'd recommend the package async for a callback based solution or bluebird for Promises. Both have a .map function which is perfect for this use case.