How to pass data to cloud function file in flutter - flutter

Question

I am new to flutter and I have just created app that accepts payments from user using flutter_stripe: ^2.1.0 plugin. The amount in cloud function file index.js is fixed but I want to pass the amount that is calculated dynamically. Here is my code.
Future<void> makePayment() async {
final url = Uri.parse(
'https://us-central1-carwashapp-376b6.cloudfunctions.net/stripePayment');
final response =
await http.get(url, headers: {"Content-Type": "application/json"});
paymentIntentData = json.decode(response.body);
await Stripe.instance.initPaymentSheet(
paymentSheetParameters: SetupPaymentSheetParameters(
paymentIntentClientSecret: paymentIntentData['paymentIntent'],
applePay: true,
googlePay: true,
style: ThemeMode.light,
merchantCountryCode: 'US',
merchantDisplayName: 'Kleen My Car',
),
);
setState(() {});
displayPaymentSheet();
}
Future<void> displayPaymentSheet() async {
try {
await Stripe.instance.presentPaymentSheet(
parameters: PresentPaymentSheetParameters(
clientSecret: paymentIntentData['paymentIntent'],
confirmPayment: true));
setState(() {
paymentIntentData = null;
});
ScaffoldMessenger.of(context)
.showSnackBar(SnackBar(content: Text('Payment succeeded')));
} catch (e) {
print('error error error');
}
}
and here is my index.js file's code
const functions = require("firebase-functions");
const stripe = require("stripe")(functions.config().stripe.testkey);
exports.stripePayment = functions.https.onRequest(async (req, res) => {
const paymentIntent = await stripe.paymentIntents.create(
{
amount: 120,
currency: "USD",
},
function (err, paymentIntent) {
if (err != null) {
console.log(err);
} else {
res.json({
paymentIntent: paymentIntent.client_secret,
});
}
}
);
});
Any kind of help is much appreciated. Thank you so much!

Answer 1

You need to adapt this line:
final response = await http.get(url, headers: {"Content-Type": "application/json"});
(Firstly, it makes no sense to give a content type on a GET, as GETs don't have any content. Remove that header.)
You could change to a POST and add the amount as a parameter, or leave it as a GET and add the amount to the URL.
With a POST, add (for example) body: {'amount': amount.toString()}
With a GET, add it to the URL, as follows:
final uri = Uri.https('us-central1-carwashapp-376b6.cloudfunctions.net', '/stripepayment', {'amount': amount.toString()});
In your cloud function access amount from the req. (For example, in the GET example, it would be req.query.amount as string.)
We also pass up other parameters like email, unique order id (to be used as the idempotency key), etc.

Answer 2

in index.js file change
const paymentIntent = await stripe.paymentIntents.create(
{
amount: 120,
currency: "USD",
},
to
const paymentIntent = await stripe.paymentIntents.create(
{
amount: req.query.amount,
currency: req.query.currency,
},
and deploy your function.
after that, in makepayment function, change your URL to
https://us-central1-carwashapp-376b6.cloudfunctions.net/stripePayment?amount=$amount&currency=$currency.
In this way, you can pass different amounts every time by changing the value of $amount variable in the URL.