node.js - How to get data back from Mongoose without using a callback? -

ultimately knowledge bad started few hours ago. in head should work:

getall: function(callback){     user.find({}, function (err, data) {         if (err) return console.error(err);         return data;     }); }  var users = api.getall();  console.log(users); //undefined 

but reason have pass callback data working so:

getall: function(callback){     user.find({}, function (err, kittens) {         if (err) return console.error(err);         callback(kittens);     }); } var users = api.getall(function (data) {     console.info(data); //does output data }); 

how can option one, easier read of 2 work?

unfortunately can't. when execute function, whatever return it. if return nothing undefined default.

instead of having readability based on getting user, should have based on you're going once you've gotten it. presumably you'll have action(s) you'll want perform on user, right? promises can make code better callbacks.

here's code re-written promise

getall: function(callback){     return user.findasync({}); } api.getall() .then(console.log) .catch(console.error);  

since wanted "perform" console.log on users (and/or console.error on err in case happens) that's above code does.

^{note used findasync, came bluebird's promisification}

but more realistically you'd have functions other things to/with user

api.getall() .then(filtersome) .then(manipulatesome) .then(sendsomewhere) .catch(console.error);  

each of functions might this:

function filtersome(users){     return users.reduce(function(p,e){         if(…) p.push(e);         return p; },[]);  } 

they can async functions in case you'll have use more promises:

function manipulatesome(users){     return new promise.all(user.map(function(user){         return new promise(function(resolve){             someasyncfunction(user, function(err, result){                 user.someprop = result.manipulated;                 resolve(user); }); }); }));} 

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if still looks messy, know upcoming es7 above syntactic sugar , this:

getall: async function(callback){     return user.findasync({}); } try{     var users = await api.getall();     console.log(users); catch(e){     console.error(e) } 

you start using today transpilers babeljs