Can't map Model values to formcontrols

When i am trying to map the response from server to formcontrols in angular 6. and it waits for an Event like scrolling or keyUp to map the value. Even if there is value in the model, its not mapping? how can i solve this problem

this.patientRegistrationService.getdata(data).subscribe(result=>
       {
this.pmaster=result.pmaster;
//pmaster is a model
}