title: How Can I Count Object's in Array With Given Property Value (Angular-FirebaseRealtime)
body: <p><a href="https://prnt.sc/qo0iig" rel="nofollow noreferrer">https://prnt.sc/qo0iig</a></p>
  
  <p>I want to count 'statu' when it's true. How can I ?</p>
  
  <p>component.ts</p>
  
  <pre><code>getAttDetails(ıd){
          this.afAuth.user.subscribe(user =&gt; this.serviceCourses.getAttDetails(ıd,user).subscribe(detail =&gt; console.log(detail)));
        }
  </code></pre>
  
  <p>serviceCourses</p>
  
  <pre><code>getAttDetails(ıd,user:firebase.User){
      return  this.db.list('/denemeDersler/'+ıd+'/attendance/'+user.uid).snapshotChanges().pipe(map(changes =&gt; changes
        .map(c =&gt; ({key: c.payload.key, ...c.payload.val()}))));
     }
  </code></pre>