What is the reason behind an empty array being interpreted as never when using Angular's NonNullableFormBuilder?
public form = this.fb.group({
item: [[]],
});
After running:
this.form .patchValue({
item: someValue,
});
I am faced with the error message:
Type 'SomeType[]' is not assignable to type 'never'.Is there a solution to make it work properly?
Explanation for the behavior you're encountering can be attributed to the group() function
export abstract class NonNullableFormBuilder {
abstract group<T extends {}>(
controls: T,
options?: AbstractControlOptions|null,
): FormGroup<{[K in keyof T]: ɵElement<T[K], never>}>;
}
In simpler terms:
function foo<T>(t: T): T {
return t;
}
const a = foo([]); // never
const b = foo([] as Array<number>); // number[]
The compiler infers an empty array as never[]. By casting your array, you can resolve this issue.
If you're having trouble, consider using the setValue() function instead of patchValue().
this.form.setValue({
key: value
});
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