Unhandled Exception: type 'List<dynamic>' - flutter

Question

I'm trying to recieve a list from a Sql Api. The catch is that i need to give an id with the query. the Widget.klant.klantId has the value i need. i know it has somthing to do with the as List<Machine> in accountpage.dart. Hope you can help me with this problem. thanks in advance.
The hole error:
accountpage.dart:
class Accountpage extends StatefulWidget {
const Accountpage(this.klant);
final Klant klant;
#override
_AccountpageState createState() => _AccountpageState();
}
class _AccountpageState extends State<Accountpage> {
_AccountpageState();
final ApiService api = ApiService();
late List<Machine> machineList;
#override initState(){
super.initState();
_getMachine();
machineList = [];
}
void _getMachine() async{
machineList = (await ApiService().getMoreMachine(widget.klant.klantId.toString())) as List<Machine>;
Future.delayed(const Duration(seconds: 1)).then((value) => setState(() {}));
}
#override
Widget build(BuildContext context) {
//Here starts the body
api_machine.dart:
Future<Machine> getMoreMachine(String klantId) async {
final response = await get(Uri.parse('$apiUrl/Select/$klantId'));
if (response.statusCode == 200) {
return Machine.fromJson(json.decode(response.body));
} else {
throw Exception('Failed to load a case');
}
}
MachineModel.dart:
List<Machine> welcomeFromJson(String str) => List<Machine>.from(json.decode(str).map((x) => Machine.fromJson(x)));
String welcomeToJson(List<Machine> data) => json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Machine {
Machine({
this.serienummerId,
this.serienummer,
this.bouwjaar,
this.urenstand,
this.locatie,
this.klantId,
});
int? serienummerId;
String? serienummer;
String? bouwjaar;
String? urenstand;
String? locatie;
String? klantId;
factory Machine.fromJson(Map<String, dynamic> json) => Machine(
serienummerId: json["SerienummerId"],
serienummer: json["Serienummer"],
bouwjaar: json["Bouwjaar"],
urenstand: json["Urenstand"],
locatie: json["Locatie"],
klantId: json["KlantId"],
);
Map<String, dynamic> toJson() => {
"SerienummerId": serienummerId,
"Serienummer": serienummer,
"Bouwjaar": bouwjaar,
"Urenstand": urenstand,
"Locatie": locatie,
"KlantId": klantId,
};
}
json result
[
{
"SerienummerId": 1,
"Serienummer": "-----",
"Bouwjaar": "2020",
"Urenstand": "10",
"Locatie": "---",
"KlantId": "1"
},
{
"SerienummerId": 2,
"Serienummer": "-----",
"Bouwjaar": "1998",
"Urenstand": "5010",
"Locatie": "----",
"KlantId": "1"
}
]

Answer 1

You are parsing the result as if it's a single Machine while it in fact is a list of machines. Process it as a list and also use the correct return type accordingly. Like
Future<List<Machine>> getMoreMachine(String klantId) async {
final response = await get(Uri.parse('$apiUrl/Select/$klantId'));
if (response.statusCode == 200) {
return List<Machine>.from(json.decode(response.body).map((x) => Machine.fromJson(x)));
} else {
throw Exception('Failed to load a case');
}
}

Answer 2

the return type of the method is Machine:
Future<Machine> getMoreMachine(String klantId) async {
final response = await get(Uri.parse('$apiUrl/Select/$klantId'));
if (response.statusCode == 200) {
return Machine.fromJson(json.decode(response.body));
} else {
throw Exception('Failed to load a case');
}
}
and then you cast a Machine to List :
machineList = (await ApiService()
.getMoreMachine(widget.klant.klantId.toString())) as List<Machine>;
I don't know what the JSON looks like... but if there is only one machine you could for example add it to a list like this:
machineList.add((await ApiService()
.getMoreMachine(widget.klant.klantId.toString())));
Update
Try this:
Future<List<Machine>> getMoreMachine(String klantId) async {
final response = await get(Uri.parse('$apiUrl/Select/$klantId'));
if (response.statusCode == 200) {
final jsonMachines = Machine.fromJson(json.decode(response.body));
return jsonMachines.map((item) => Machine.fromJson(item)).toList();
} else {
throw Exception('Failed to load a case');
}
}

Answer 3

I think this is because of in getMoreMachine you used return type as Machine actually you are assigning that value as List so make that change like this :
Future<List<Machine>> getMoreMachine(String klantId) async {
final response = await get(Uri.parse('$apiUrl/Select/$klantId'));
if (response.statusCode == 200) {
return welcomeFromJson(response.body);
} else {
throw Exception('Failed to load a case');
}
}
might be other think is you can check your API response that is not returning List of machines.