Error saving data in Rest API - Flutter/Dart - json

Question

I have the following return from the API (which I can return normally on my main screen!):
[
{
"id": 1,
"obs": "",
"dataVcto": "2022-11-02T00:00:00.000Z",
"valor": 200,
"idTPRD": 1,
"dataLcto": "2022-11-02T00:00:00.000Z",
"status": "A",
"idUSRS": 1,
"dC": "C",
"idCTCT": 1,
"tPRD_Nome": "FRETE",
"uSRS_Nome": "Heugenio",
"cTCT_Nome": "Frete p\/Terceiros"
},
{
"id": 2,
"obs": "Maquina Vilmar",
"dataVcto": "2022-12-01T00:00:00.000Z",
"valor": 300,
"idTPRD": 1,
"dataLcto": "2022-11-05T00:00:00.000Z",
"status": "A",
"idUSRS": 1,
"dC": "C",
"idCTCT": 1,
"tPRD_Nome": "FRETE",
"uSRS_Nome": "Heugenio",
"cTCT_Nome": "Frete p\/Terceiros"
},
{
"id": 5,
"obs": "",
"dataVcto": "2022-12-01T00:00:00.000Z",
"valor": 200,
"idTPRD": 2,
"dataLcto": "2022-11-05T00:00:00.000Z",
"status": "A",
"idUSRS": 1,
"dC": "D",
"idCTCT": 1,
"tPRD_Nome": "OLEO",
"uSRS_Nome": "Heugenio",
"cTCT_Nome": "Frete p\/Terceiros"
}
]
My model class (Automatically generated on a website that creates these classes):
class LancamentosModel {
int? id;
String? obs;
String? dataVcto;
int? valor;
int? idTPRD;
String? dataLcto;
String? status;
int? idUSRS;
String? dC;
int? idCTCT;
String? tPRDNome;
String? uSRSNome;
String? cTCTNome;
LancamentosModel(
{this.id,
this.obs,
this.dataVcto,
this.valor,
this.idTPRD,
this.dataLcto,
this.status,
this.idUSRS,
this.dC,
this.idCTCT,
this.tPRDNome,
this.uSRSNome,
this.cTCTNome});
LancamentosModel.fromJson(Map<String, dynamic> json) {
id = json['id'];
obs = json['obs'];
dataVcto = json['dataVcto'];
valor = json['valor'];
idTPRD = json['idTPRD'];
dataLcto = json['dataLcto'];
status = json['status'];
idUSRS = json['idUSRS'];
dC = json['dC'];
idCTCT = json['idCTCT'];
tPRDNome = json['tPRD_Nome'];
uSRSNome = json['uSRS_Nome'];
cTCTNome = json['cTCT_Nome'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['obs'] = this.obs;
data['dataVcto'] = this.dataVcto;
data['valor'] = this.valor;
data['idTPRD'] = this.idTPRD;
data['dataLcto'] = this.dataLcto;
data['status'] = this.status;
data['idUSRS'] = this.idUSRS;
data['dC'] = this.dC;
data['idCTCT'] = this.idCTCT;
data['tPRD_Nome'] = this.tPRDNome;
data['uSRS_Nome'] = this.uSRSNome;
data['cTCT_Nome'] = this.cTCTNome;
return data;
}
}
When I try to save the data in this listing by the application, I get this exception:
Error: Expected a value of type 'String', but got one of type 'int'
action on the button to save the data:
ElevatedButton(
onPressed: () {
var dados = LancamentosModel(
dataLcto: _dataController.text.toString(),
dataVcto: _vencimentocontroller.text.toString(),
obs: _obsController.text.toString(),
valor: int.tryParse(_valorController.text.toString()),
status: _controller.toString(),
dC: _type.toString(),
uSRSNome: "Felippe",
cTCTNome: "Frete",
tPRDNome: "Óleo",
id: 2,
idCTCT: 1,
idTPRD: 1,
idUSRS: 1
);
salvarDados(dados);
},
salvarDados() method:
Future salvarDados(LancamentosModel dados) async {
var resp = await http.post(
Uri.parse("http://hjsystems.dynns.com:8085/GravaLancamentos"),
headers: {
"Authorization": "Basic *******************"
},
body: dados.toJson());
if (resp.statusCode != 200) Exception("Erro ao salvar");
}

Answer 1

You toJson() method does not actually produce JSON, it just produces a data structure that can be serialized as JSON. That is correct. This is the pattern we use.
But you need to actually serialize it as JSON text:
body: jsonEncode(dados.toJson()),