Iterate through firebase values

Question

I would like to access the comments array and do some calculations to render the average of ratings (avgstars) and show the numbers of comments on a particular item in my firebase array.

Any idea?

ngOnInit() {
  this.route.params
    .pipe(switchMap((params: Params) => this.dishservice.getDish(params['id'])))
    .subscribe(dish => {
      this.dish = dish
      this.favorite = this.favoriteService.isFavorite(this.dish.id); 

      //compute the average of the comments and the render the length of the array
      this.numcomments = /* This is the locus --->*/ this.dish.comments.length;           
      let total =0; 
      this.dish.comments.forEach(comment =>total += comment.rating); 
      this.avgstars = (total/this.numcomments).toFixed(2); 
         },
        errmess => this.errMess = <any>errmess); 
      }

Here is the data sample

NB: The above snippet was working fine when the ids were numbers not alphanumeric. — Wilson_0, May 29 '20 at 22:49

score 1 · Answer 1 · answered May 29 '20 at 23:15

1

It looks like "comments" is an object and not an array. therefore you will fail getting a number via "length".

you may try it iterate thru the object keys.

see here: How do I loop through or enumerate a JavaScript object?

answered May 29 '20 at 23:15

gsa.interactive

565
2
7

How would you correct the above snippet using object keys iteration? – Wilson_0 May 30 '20 at 08:43

score 1 · Accepted Answer · answered May 30 '20 at 19:55

You don't have change your firebase data model as long as you create a new Array by iterating your "key" (-M8V...) values from the "comments" object.

I would do something like this:

let p = this.dish[0].comments;
for (let [key, value] of Object.entries(p)) {
  console.log(key, value);
}

Iterate through firebase values

2 Answers2