How can I use the returned value of data I got from my shared preference json file as a parameter - flutter

Question

how can i use this as my url parameter
userData['UserName']
I have json data in my shared preference file. So I tried to get the username
of the signed in user because I want to use as a parameter to an endpoint.
I can print the username quite ok on the console but when tried to add it
on the link, the statusCode response I get is:
null.
E/flutter ( 906): Receiver: null
E/flutter ( 906): Tried calling: []("UserName")
please how can I extract his username and add it to the endpoint:
Here's the endpoint that shared preference snippet that gives me the
username:
var q;
var userData;
void _getUserInfo() async {
SharedPreferences localStorage = await SharedPreferences.getInstance();
var userJson = localStorage.getString('loginRes');
user = json.decode(userJson);
setState(() {
userData = user;
});
print(userData['UserName']);
}
and this is where I want to use it, on the get request link below:
Future<void> get_farmer_eop() async {
final response = await http.get(
'http://api.ergagro.com:112/GenerateFarmersEop?farmerBvn=${widget.result}&dcOid=${widget.dc_result}&agentName=${userData['UserName']}',
headers: _setHeaders());
print('${response.statusCode}popo');
if (response.statusCode == 200) {
final jsonStatus = jsonDecode(response.body);
setState(() {
q = jsonStatus['Eop'];
});
print('trandid');
print('${q['TransId']}kukuk');
} else {
throw Exception();
}
}
_setHeaders() => {
'Content-type': 'application/json',
'Accept': 'application/json',
};
But on the console I print the username and if I tried to hardcode the agentName which is the username parameter example agentName=johndoh it works but when userData['UserName'] I keep getting null please can anyone help me?

Answer 1

If _getUserInfo not returning anything then why to create a separate method, try below code. It should work.
Future<void> get_farmer_eop() async {
SharedPreferences localStorage = await SharedPreferences.getInstance();
var userJson = localStorage.getString('loginRes');
user = json.decode(userJson);
final response = await http.get(
'http://api.ergagro.com:112/GenerateFarmersEop?farmerBvn=${widget.result}&dcOid=${widget.dc_result}&agentName=${user['UserName']}',
headers: _setHeaders());

Answer 2

You are using a wrong formatted url, try this instead:
final response = await http.get(
"http://api.ergagro.com:112/GenerateFarmersEop?farmerBvn=${widget.result}&dcOid=${widget.dc_result}&agentName=${userData['UserName']}",
headers: _setHeaders());