added support for json_strip_nulls and jsonb_strip_nulls

[zaira-bibi]

Added support for functions json_strip_nulls and jsonb_strip_nulls under #4216.

[weiznich]

Thanks for opening this PR.

I added a few comments about the signatures of these functions. Additionally it would be great to have a test for json_strip_null(None) to verify that the null value handling work.

[weiznich]

We need to restrict the generic type E here to be either Jsonb or Nullable<Jsonb>. Also as we return the same output type as input type we don't need the MaybeNullableValue<Jsonb> helper type:

Suggested change

	fn jsonb_strip_nulls<E: MaybeNullableValue<Jsonb>>(jsonb: E) -> E::Out;
	fn jsonb_strip_nulls<E: JsonbOrNullableJsonb>(jsonb: E) -> E;

[weiznich]

We need to restrict the generic type E here to be either Json or Nullable<Json>. Also as we return the same output type as input type we don't need the MaybeNullableValue helper type. You likely need to define a new JsonOrNullableJson trait analog to the JsonbOrNullableJsonb trait for that.

Suggested change

	fn json_strip_nulls<E: MaybeNullableValue<Json>>(json: E) -> E::Out;
	fn json_strip_nulls<E: JsonOrNullableJson>(json: E) -> E;

[zaira-bibi]

@weiznich Thank you sm for the review! I have pushed in a commit for the requested changes. Please let me know if it's alright or if there are any further changes.

[weiznich]

Looks good, thanks for the update 🙏