ractive form patch value

 this.data.getCustomer().subscribe(res => {
              console.log(res[0]);
              this.customerForm.patchValue({
                firstName: res[0].firstName,
                lastName: res[0].lastName
              });

        for (let index = 0; index < res[0].mobile.length; index++) {
        this.mobiles.controls.push(this.buildNumber());
        this.mobiles.at(index).patchValue({
        number: res[0].mobile[index].number,
        });
        }
        this.mobiles.controls.pop();
        });