Is there a way to serialize a json response (from a .net API) to replace $ref objects in the list with the complete object in dart?

Question

I have an API that returns a response similar to the one shown in this post.

My response comes back with objects in the list only containing a $ref variable that is pointing to a child object somewhere in the list with a relating $id.

I tried the following but it would not work for larger more complicated responses and I suspect that it would increase the compute time a lot:

Future<List<Category>> getCategories() async {
String token = await FlutterSession().get("accessToken");
final response =
    await http.get('$url/api/categories/', headers: <String, String>{
  'Content-Type': 'application/x-www-form-urlencoded',
  'Authorization': 'Bearer  ' + token,
});

if (response.statusCode == 200) {
  categories = categoriesFromJson(response.body);
  var incompleteCats = categories.where((c) => c.id == null);
  incompleteCats.forEach((ic) {
    categories.remove(ic);
    var completeCat =
        categories.where((s) => s.parent?.$id == ic.$ref).first.parent;
    categories.add(completeCat);
  });
  return categories;
} else {
  throw Exception('Failed to get categories');
}

}

Example of API Response

[
{
    "$id": "3",
    "Parent": {
        "$id": "4",
        "Parent": {
            "$ref": "1"
        },
        "CategoryName": "General",
        "Description": "Test",
        "ParentCategoryId": 45,
        "SortOrder": 2,
        "Id": 49,
        "IsDeleted": false,
        "CreatedDate": "2009-11-29T00:00:00",
        "CreatedByUserId": 1,
        "UpdatedDate": "1900-01-01T00:00:00",
        "UpdatedByUserId": null,
        "State": 0
    },
    "CategoryName": "Country",
    "Description": "Test",
    "ParentCategoryId": 49,
    "SortOrder": 3,
    "Id": 47,
    "IsDeleted": false,
    "CreatedDate": "2019-11-29T00:00:00",
    "CreatedByUserId": 1,
    "UpdatedDate": "1900-01-01T00:00:00",
    "UpdatedByUserId": null,
    "State": 0
},
{
    "$id": "16",
    "Parent": {
        "$ref": "4"
    },
    "CategoryName": "Other",
    "Description": "Other",
    "ParentCategoryId": 49,
    "SortOrder": 7,
    "Id": 61,
    "IsDeleted": false,
    "CreatedDate": "2020-06-05T09:13:50.863",
    "CreatedByUserId": 1,
    "UpdatedDate": "2020-06-05T09:13:50.863",
    "UpdatedByUserId": 1,
    "State": 0
},
{
    "$ref": "4"
},

]