should `createFormArrayControl` accept null values for the `value` object

[maxime1992]

When dealing with FormArray, I believe a common use case is to click a button to add an empty entry in the array and later on from the UI fill it up.

Currently the definition is:

protected createFormArrayControl(
  key: ArrayPropertyKey<StackedNonCuttingCylinders.AsObject> | undefined,
  value: ArrayPropertyValue<StackedNonCuttingCylinders.AsObject>,
): FormControl

and value doesn't accept an object with all the required keys but with null values.

I think it should.

Anyone second that?

[maxime1992]

Also to clarify, as it's just typing the current work around is just to apply as any on all the null values but this is obviously not ideal.

[zakhenry]

I think I'm confused by your example, but I agree with the general idea.

I do you mean that the value argument should include | null ?

[maxime1992]

I think it should be

export type NullableProps<T> = { [P in keyof T]: T[P] | null };

protected createFormArrayControl(
  key: ArrayPropertyKey<StackedNonCuttingCylinders.AsObject> | undefined,
  value: NullableProps<ArrayPropertyValue<StackedNonCuttingCylinders.AsObject>>,
): FormControl

But not

protected createFormArrayControl(
  key: ArrayPropertyKey<StackedNonCuttingCylinders.AsObject> | undefined,
  value: null | ArrayPropertyValue<StackedNonCuttingCylinders.AsObject>,
): FormControl

[zakhenry]

Do you mean to say that we would pass {} as value for the null case? Why not null?

[zakhenry]

Especially as array controls can reasonable be primitive types not objects