Display amount of comments from different database table - angularjs

Question

Before I start coding I'm trying to figure out how I'd do it first. So what I want to do is to display a list of articles, by simply loading it from a database for example: getAllArticles().
The list will display all the titles from the articles. Nothing difficult about that.
However, there's a chance to comment on that article so all the comments will be stored in a new database tabel with the ID of the article.
I'll probably have to load them with getAllCommentsById() but how do I display the amount of comments next to each article in an ng-repeat?
I don't have any code yet, but let's say it will look like this:
Angular
<div ng-repeat='article in articles'>
<p>{{amount}}</p>
<p>{{article.title}}</p>
</div>
$scope.articles = getAllQuestions();
Article database
{
"id":1,
"title": "Article 1"
}
{
"id":2,
"title": "Article 2"
}
Comments database
{
"id":1,
"comment": "Lorem ipsum",
"article_id": 1
},
{
"id":2,
"comment": "Lorem ipsum",
"article_id": 1
},
{
"id":3,
"comment": "Lorem ipsum",
"article_id": 2
}

Answer 1

I think that you can do it in two several ways.
You can add a counter of the comment relatives to an article in the articles object
Create a function in angular's controller that give the number of comments of an article
$scope.countComments = function(articleId) {
...
}
Create an angular service that count the comments of each article