Why not displaying card - flutter

Question

I want to intigrate stripe payment but i got this error
** FlowController must be successfully initialized using configureWithPaymentIntent() or configureWithSetupIntent() before calling presentPaymentOptions()**
How solve this error also it is not displaying any card
Center(
child: ElevatedButton(
onPressed: () {
intpayment(email: "email,amount: 50.0);
},
child: Text("Pay20\$"),
),
),
Future<void> intpayment(
{required String email, required double amount})async{
try{
final response= await http.post(Uri.parse("https://api.stripe.com/v1/payment_intents")
,body:{
"receipt_email": email,
"amount": amount.toInt().toString(),
"currency": "usd"
},
headers: {
'Authorization': 'Bearer ' + 'key',
'Content-Type': 'application/x-www-form-urlencoded'
}
);
final jsonresponse=jsonDecode(response.body); Stripe.instance.initPaymentSheet(paymentSheetParameters: SetupPaymentSheetParameters(
paymentIntentClientSecret: jsonresponse['paymentIntent'],
merchantDisplayName: 'Zohaib',
));
await Stripe.instance.presentPaymentSheet();
Fluttertoast.showToast(
msg: "payment successfully",
);
}
catch(e){
if (e is StripeException) {
Fluttertoast.showToast(
msg: "Stripe error $e",
);
}
Fluttertoast.showToast(
msg: "$e",
toastLength: Toast.LENGTH_SHORT, );
}
}

Answer 1

You need to create the PaymentIntent on the server-side and not within your flutter app.
final response= await http.post(Uri.parse("https://api.stripe.com/v1/payment_intents")
,body:{
"receipt_email": email,
"amount": amount.toInt().toString(),
"currency": "usd"
},
headers: {
'Authorization': 'Bearer ' + 'key',
'Content-Type': 'application/x-www-form-urlencoded'
}
);
Instead of calling the Stripe API directly as you did in the code above, you should call your own API and generate a Payment Intent and just send the client_secret to your flutter App, otherwise you would be exposing your secret key and thus giving access to your data. This is described here.
Once you do this server-side part the rest is explained here.