Firebase on（'child_added'正在添加更多不需要的孩子/.once仅返回数组中的最后一个

Question

Working on a node script to automatically call Google's pagespeed api upon giving the sites listed in a json file.

{
  "1" : "https://bitbucket.org",
  "2" : "https://www.catswhocode.com/blog/"
}

The aim is to add the results for the api call to firebase json database along with a top-level url node to store the firebase key for the sitestats entered. Here is example firebase data structure I need.

sites
 -KrehhWxld7XlKCuFSHRY
   stats { ... }
   url: "https://bitbucket.org"
 -KrehhXAWlYdjAOA9sd95
   stats { ... }
   url: "https://stackoverflow.com"
urls :
 393957be871e209a76e0dc5df1f526ec : -KrehhWxld7XlKCuFSHRY
 7f4c919540be6ec81cd37d9e61da6c37 : -KrehhXAWlYdjAOA9sd95

Within a promise I am adding a reference for the nodes in firebase json database.

Promise.all(allRes).then( function( values ) {
var ref = db.ref();
var sitesRef = ref.child("sites");
var urlsRef = ref.child("urls");
var psiresults = {};
  SitesArray.map(function (sites, index) {
    psiresults[sites] = values[index]
    desktopStats = values[index].desktopStats;
    mobileStats = values[index].mobileStats;
    sitesRef.push({
      url: sites,
      stats: metricsResponse
    });
    sitesRef.once('child_added', function(snapshot) {
      console.log(snapshot.key) //returns the last key only
    });
  });

When using once('child_added', ... it adds to the url top level node only for the very last item. However, if on('child_added', ... multiple copies of the same data and other childs are added. Not sure how to add the exact child key to the urls top level node when a child is added to sites node each time.

Answer 1

If you want to process all URLs once, use once('value' with snapshot.forEach() :

sitesRef.once('value', function(snapshot) {
  snapshot.forEach(function(child) {
    console.log(child.key);
  });
});

Answer 2

Finally, I had to do it using..

sitesRef.on('value', function(snapshot) {
  ... 
});

This returns all the children and then I am able to filter the result based on my SitesArray values. I don't really find this an appropriate solution, however, I was able to make it work.