add control to formgroup angular 4 with value code example

Example 1: formgroup addcontrol

let form: FormGroup = new FormGroup({});
form.addControl(field_name, new FormControl('', Validators.required));

Example 2: update formgroup value angular

To set all FormGroup values use, setValue:

this.myFormGroup.setValue({
  formControlName1: myValue1, 
  formControlName2: myValue2
});
To set only some values, use patchValue:

this.myFormGroup.patchValue({
  formControlName1: myValue1, 
  // formControlName2: myValue2 (can be omitted)
});