Firebase.update failed : first argument contains undefined in property

Question

I have a simple Firebase function that updates some data. However, the interpreter says that the first argument contains \"undefined\" in property \'users.tester1\'. Can somebod

Answer 1

When you pass an object to Firebase, the values of the properties can be a value or null (in which case the property will be removed). They can not be undefined, which is what you're passing in according to the error.

Simply running this snippet in isolation shows the problem:

var objify = function() {
  var rv = {};
    for (var i = 0; i < arguments.length; ++i)
      rv[arguments[i]] = rv[arguments[i+1]];
    return rv;
}
objify("name", "filler")

Results in:

{name: undefined, filler: undefined}

My best bet is that you want to pass key/value pairs into objify as even/odd parameters. In that case you want to change the function to:

var objify = function() {
  var rv = {};
    for (var i = 0; i < arguments.length; i+=2)
      rv[arguments[i]] = arguments[i+1];
    return rv;
}
objify("name", "filler")

Results in:

{name: "filler"}

Answer 2

The underlying Firebase library throws an error when you try to update a property with the value of undefined. It will allow null (and will essentially ignore them).

You'll need your raw transformer to ensure that it ignores all prototype methods and properties and converts undefined to null or removes any properties with with undefined values altogether.

var addUser = function(name, edges){
  if(!checkIfUsernameExists(name) && !checkIfNodeNameExists(name) && !checkIfEdgeNameExists(name)){
    var time = Firebase.ServerValue.TIMESTAMP;

    //HERE: I think the error is on this line 
    refs.users.update(objify(name, "filler"));

    refs.users.child(name).set({
      "id" : time || null,
      "edges" : "filler" || null
    });
    refs.users.child(name).child("edges").update({
      "to" : "filler" || null,
      "from" : "filler" || null
    });

    addNode(new Node(name, time, name));

Answer 3

to make sure your object does not contain any undefined props use this simple trick:

JSON.parse( JSON.stringify(YourJsonData ) )

For more info take a look at this codePen: http://codepen.io/ajmueller/pen/gLaBLX

Answer 4

Like said above, you need all undefined values to be null if you want them to save as empty values in firebase.

I take this approach to correct all nested values.

  //to search and replace    
    const replaceAll  =(s="",f="",r="")=>  s.replace(new RegExp(f.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&'), 'g'), r)

    //to save 
   firebase.database().ref(`path`).update(JSON.parse(replaceAll(JSON.stringify(val),"undefined","null")))