Create a class that calls a future for reusability - flutter

Question

I have a future that is used a few different times on some pages and I'm trying to include it instead and reference it when needed to cut down on the code overhead.
I've created a working future and wrapped it inside a class, the problem is that Flutter states that
"2 positional argument(s) expected, but 0 found."
I've tried String and Function type declarations for the client variable and I am including them, but I'm not sure what else I'm missing here?
FetchCats.getCats(client: http.Client(), filter: filter);
class FetchCats {
String client; <-- this shouldn't be string but I don't know what else to declare it as
int catType;
FetchCats({Key? key, required this.client, required this.catType});
Future<List<CatDetails>> getCats(http.Client client, int catType) async {
var ct = catType;
var catResults;
var response = await client.get(Uri.parse('/cats/breeds/$ct/'));
if (response.statusCode == 200) {
catResults = compute(convertCatDetails, response.body);
} else {
print("error");
}
return catResults;
}
}
List<CatDetails> convertCatDetails(String responseBody) {
final parsed = jsonDecode(responseBody).cast<Map<String, dynamic>>();
return parsed
.map<CatDetails>((json) => CatDetails.fromJson(json))
.toList();
}

Answer 1

Your function is defined using positional parameters, rather than named parameters, but you are calling it with named arguments.
Here are a few changes that should allow you to use the class as I think you're intending:
It's not necessary to store catType on the class, since that's something you would probably change between requests - so it makes more sense to only pass it into the getCats function.
To fix the positional parameter issue, you can also change catType into a named parameter.
You don't need a Key parameter on the constructor - those are usually used with Widgets.
The type of the client should be http.Client, not String.
With those changes, your class should look something like this:
class FetchCats {
final http.Client client;
FetchCats({required this.client});
Future<List<CatDetails>> getCats({required int catType}) async {
int ct = catType;
var catResults;
var response = await client.get(Uri.parse('/cats/breeds/$ct/'));
if (response.statusCode == 200) {
catResults = compute(convertCatDetails, response.body);
} else {
print("error");
// Return an empty list, rather than the uninitialized catResults
return [];
}
return catResults;
}
}