It sounds like you want that getter to return the entire FormArray, which means all you need is this,
return this.dataForm.get('myFormArray') as FormArray;
Or if you want the control at a specific index of the FormArray you can access it like this,
public getControlAtIndex(index: number): AbstractControl {
let myFormArray: FormArray = myForm.get('myFAControl') as FormArray;
return myFormArray.at(index);
}
If the control at some index is a FormArray, then querying that index with this function would return the entire nested FormArray.
There are some other tricks for grabbing the index value of a FormArray as well. Check out this answer.
But something doesn't sound right about what you are trying to do.. It sounds like you're trying to update the form value with what the form value already is. If you're trying to set the initial value for each control in a FormArray you can do something like this,
for(let i = 0; i < myFormArray.controls.length; i++) {
myFormArray.at(i).setValue(myVals[i]);
}
Or,
myFormArray.setValue(["val1", "val2", ...]);