How can I implement WooCommerce REST API "orderby" successfully? - wordpress

Question

I'm creating a mobile application using flutter and I'm currently trying to list products with the ability to sort them, but everytime I try to implement the "orderby" parameter, I get this error:
I/flutter ( 5187):
{
"code":"rest_invalid_param",
"message":"Invalid parameter(s): orderby",
"data":
{
"status":400,
"params":
{
"orderby":"orderby is not one of date, id, include, title, slug, price, popularity, and rating."
},
"details":
{
"orderby":
{
"code":"rest_not_in_enum",
"message":"orderby is not one of date, id, include, title, slug, price, popularity, and rating.",
"data":null
}
}
}
}
The code where I get the error:
Future<List<Product>> getProducts({
int pageNumber,
int pageSize,
String strSearch,
String tagName,
String categoryID,
String sortBy,
String sortOrder = "asc",
}) async {
List<Product> data = [];
try {
String parameter = "";
if (strSearch != null) {
parameter += "&search=$strSearch";
}
if (pageSize != null) {
parameter += "&per_page=$pageSize";
}
if (pageNumber != null) {
parameter += "&page=$pageNumber";
}
if (tagName != null) {
parameter += "&tag=$tagName";
}
if (categoryID != null) {
parameter += "&category=$categoryID";
}
if (sortBy != null) {
parameter += "&orderby=$sortBy";
}
if (sortOrder != null) {
parameter += "&order=$sortOrder";
}
String url = Config.url +
Config.productsURL +
"?consumer_key=${Config.key}&consumer_secret=${Config.secret}${parameter.toString()}";
var response = await Dio().get(
url,
options: Options(
headers: {
HttpHeaders.contentTypeHeader: "application/json",
},
),
);
if (response.statusCode == 200) {
data = (response.data as List)
.map(
(i) => Product.fromJson(i),
)
.toList();
}
} on DioError catch (e) {
print(e.response);
}
return data;
}
In a couple of other similar questions, I've been seeing that I need to add a filter looking like this:
add_filter( 'rest_product_collection_params', array( $this, 'filter_add_rest_orderby_params' ), 10, 1 );
add_filter( 'rest_product_cat_collection_params', array( $this, 'filter_add_rest_orderby_params' ), 10, 1 );
function filter_add_rest_orderby_params( $params ) {
$params['orderby']['enum'][] = 'menu_order';
return $params;
}
I wanted to try this, however, I'm not sure if this would work in my case, and does anyone know what specific file I am going to edit to add this filter? I can't seem to find where people put it. (I'm using Wordpress.)