Node.js Question
token generator in node and express
I trying create a function that generates a random token that doesn't exist in my database (Mongodb) and I use a unique property in my user schema. This is my function:
var UniqueTokenGenerator = function () {
var token = uuid.v4();
UserModel.findOne({token : token} , (err , user)=> {
if(err)
res.status(500).send(err);
else if(user){
//1
}else if(!user){
return token; //2
}
});
};
My problems:
- I want if token exist call UniqueTokenGenerator or whatever... like loop.
- Token cannot be returned.
- Anybody has a better idea?
I don't want to use any library like
jwt
Answer Source
Two answers:
First, you don't need to check the database to make sure your UUID is unique. UUIDs are so big that mathematically you won't run into a collision. See Are GUID collisions possible?
Second, to do what you're trying to do, you need to make your function asynchronous and deliver the result with a callback. E.g.
var generateUniqueToken = (callback) => {
var token = uuid.v4();
UserModel.findOne({ token: token }, (err, user) => {
if(err) {
// First parameter of the callback is an error.
callback(err);
} else if (user) {
// Try again.
generateUniqueToken(callback);
} else if (!user) {
// First parameter of the callback is an error. The second
// parameter is the successful result.
callback(null, token);
}
});
};
// Example usage:
generateUniqueToken((err, token) => {
if (err) {
res.status(500).send(err);
} else {
// Use the token here.
}
});