Javascript List Object can't add JSON? Node.JS, Firebase

Question

router.get('/getAllMeals',function(req,res){    

    var allMeals = [];
    allMeals.push("foo");

    mealsRef.on("value",function(dataSnapShot){
        dataSnapShot.forEach(function(child){
            console.log(child.val());
            var oneMeal = child.val();
            allMeals.push(oneMeal);
        });
    }); 

    allMeals.forEach(function(obj){
        console.log(obj);
    });

    res.send(allMeals);
}); //RETRIEVE ALL

In the above code, I cannot add oneMeal which is a valid JSON object to the allMeals array I created. The result of console.log only shows the "foo" and also the length is 1.

I submitted a fix for your code, you knew there was an extra }); ? — jrbedard
– jrbedard, Commented Sep 20, 2016 at 23:58

Jeffrey A. Gochin · Accepted Answer · 2016-09-20 23:59:26Z

3

Assuming mealsRef.on("value",function(dataSnapShot){ is a valid event; your res.send(allMeals); needs to be called in that callback. Basically you are responding too soon.

answered Sep 20, 2016 at 23:59

Jeffrey A. Gochin

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3 Comments

qxz Over a year ago

A good read for every NodeJS developer, on asynchronous programming: Callback Hell.

Jeffrey A. Gochin Over a year ago

A much better development pattern would be to use ES6 promises. Using Promises completely avoids "callback hell." If you are not using ES6 yet, there is a NodeJS polyfill available on NPM. Here is a link to the polyfill. github.com/stefanpenner/es6-promise

Jeffrey A. Gochin Over a year ago

Also, here is a link to the MDN site, which explains their implementation of Promises. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

cshion · Accepted Answer · 2016-09-21 03:47:14Z

0

Just move res.send after datasnapshot.foreach inside callback , async hell is beating you.

answered Sep 21, 2016 at 3:47

cshion

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