How to post a map of string and list with flutter - flutter

Question

I am trying to send a Map of string and list which is like:
Map<String, List<int>> results = {
"tags": [5 , 10]
}
Object headers = {
HttpHeaders.authorizationHeader: "Bearer ${accessToken}",
"Accept": "application/json",
};
and I post that like this:
post() {
return http
.post("$resource/$baseName/$id$query",
headers: headers,
body: results ,
)
.then((http.Response response) {
return json.decode(response.body);
}).catchError((err) {
print(err);
});
}
and I got this error:
type 'List<int>' is not a subtype of type 'String' in type cast
also I guess that I should send
Map<String,String>
but I have
Map<String, List<int>>
I try many things but am also new to flutter so I got confusing a lot
Thanks if someone can help me .
EDIT:
i try with dio
try {
Response response =
await Dio().post("$resource/$baseName/$id$query", data: {
'tags': [1, 2]
},
options: Options(headers: headers)
);
print(response);
} catch (e) {
print(e);
}

Answer 1

Are you encoding your data when you send it? Try encoding your data before sending it. You specify your header to accept application/json, but you might not be sending json.
See: https://api.dartlang.org/stable/2.5.0/dart-convert/jsonEncode.html
import 'dart:convert';
Map<String, List<int>> results = {
"tags": [5 , 10]
};
final encodedResults = jsonEncode(results); // send these encoded results.

Answer 2

How do you create this map?
Wouldn't it be possible to start a .toString in the list?
Note: I suggest using the Dio plugin, it makes it much easier to work with requests in webServices, in my opinion of course!
Take a look here: https://pub.dev/packages/dio
Map<String, List<int>> results = {
"tags": [5 , 10]
}
var dio = Dio();
FormData data = FormData();
final local = '$baseName/$id$query'
dio.options.baseUrl = source;
data.add('tags', results.toString);
try{
final response = await dio.post(local, data: data, options: Options(
method: 'POST',
responseType: ResponseType.json
));
final body = jsonDecode(response.data);
print(body);
}catch(e){
print(e);
return e;
}