CODEWITHSUNDEEP
angularfirebasegoogle-cloud-firestoreangularfire5
CaribeSoft
CaribeSoft

Reputation: 597

How to sum fields value from Observable with Angular 4 Firestore array

I'm new in Cloud FireStore and have been searching for many days without results, for a simple solution on how can I sum some fields value of an array coming from Observable Angular Firestore. I have a list of rows and I want sum and have the column total, here is part of my code:

constructor(private afs: AngularFirestore, private router: Router,  private route: ActivatedRoute) { 
    this.negocio = this.route.snapshot.queryParams['negocioId']
    this.movtosCollectionRef = this.afs.collection('movtos', ref => ref.where('empresa', '==', this.negocio));


    this.movtos$ = this.movtosCollectionRef.snapshotChanges().map(actions => {
        return actions.map(action => {
          const data = action.payload.doc.data() as Movtos;
          const id = action.payload.doc.id;
          return { id, ...data };
        });


    });   
  }

In my template I make the browse :

      <tbody>
            <tr *ngFor="let item of movtos$ | async" [class.completed]="item.completed">
                <td>{{ item.indate | date: 'dd/MM/yyyy - HH:mm:ss'}}</td>
                <td>{{ item.concepto }} </td>
                <td>{{ item.tipomov }} </td>
                <td>{{ item.inuser }} </td>
                <td>{{ item.importe |  currency:'USD':true:'3.2-2' }}</td>
                <td>
                    <a class="btn btn-info" (click)="editaEmpresa(item.id)" tooltip="Edita Movimiento" placement="top"><span class="glyphicon glyphicon-edit" aria-hidden="true"></span></a>

                </td>

            </tr>   

        </tbody>

And I want to get the sum of item.importe field. Does any body know how to do this? Best regards, Caribesoft

Upvotes: 0

Views: 1506

Answers (1)

Rahul Singh
Rahul Singh

Reputation: 19622

You can use map on the Observable to return the sum. eg

getSum(): Observable<number> {
    return this.observable
       .map(arr => arr.reduce((a, b) => a + b.value, 0));
}

Upvotes: 1

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