How to handle difference responses API? - flutter

Question

How to handle the difference between the results of a successful and failed fire response?
RESPONSE SUCCESS:
{
"header":{
"status":true,
"respcode":"00",
"message":"Successfully."
},
"data":{
"userid":"3485345",
"password":"3423424",
"bit18":"0000",
}
}
RESPONSE FAILED:
{
"header":{
"status":false,
"respcode":"01",
"message":"Userid Tidak Terdaftar"
},
"data":""
}

Answer 1

assuming you'll always have headers in your responses, you can do something like this:
Map<String, dynamic> res1 = {
"header": {"status": true, "respcode": "00", "message": "Successfully."},
"data": {
"userid": "3485345",
"password": "3423424",
"bit18": "0000",
}
};
Map<String, dynamic> res2 = {
"header": {
"status": false,
"respcode": "01",
"message": "Userid Tidak Terdaftar"
},
"data": ""
};
// bla = res2 for failed case
final bla = res1;
if (bla['header']['status']) {
print(res1['data']['userid']);
// do your success code here
} else {
// do your fail code here
print('fail');
}

Answer 2

I don't know why in the failed case, data is string (and not object). In theory, the failed case should have an empty object instead of a string. Any way, assuming you don't have control over the server's response, you might want to do something like below :
(The first two lines I wrote just to make sure the parsing works.)
Map<String, dynamic> mData = {
"header":{
"status":true,
"respcode":"00",
"message":"Successfully."
},
"data":{
"userid":"3485345",
"password":"3423424",
"bit18":"0000",
}
};
String jData = json.encode(mData);
Map<String, dynamic> decodedBody = json.decode(jData);
print(decodedBody["header"]["respcode"]); // prints 00
if (decodedBody['header']['status'])
{
User user = User.fromJson(decodedBody['data']);
print(user.userId); // This prints 3485345
}
else {
// login failed
}
And the User model is defined as below :
class User {
final String userId;
final String password;
final String bit18;
User({#required this.userId, #required this.password, this.bit18});
User.fromJson(Map json)
: this.userId = json['userid'],
this.password = json['password'],
this.bit18 = json['bit18'];
}