how to allow mailto schemes in webview flutter - flutter

Question

I am working on Flutter webview apps using Flutter Webview plugin.
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:url_launcher/url_launcher.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: SafeArea(
child : const WebView(
initialUrl: 'https://google.com',
javascriptMode: JavascriptMode.unrestricted,
),
)
)
);
}
}
However, if any links inside the opened web page is an app link, like: fb://profile, I will get net::ERR_UNKNOWN_URL_SCHEME.
In android, I found the solution is to override shouldOverrideUrlLoading as mentioned here, but what should I do in flutter?
I'm trying the solution mentioned here.
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:url_launcher/url_launcher.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: SafeArea(
child : const WebView(
initialUrl: 'https://google.com',
javascriptMode: JavascriptMode.unrestricted,
navigationDelegate: (NavigationRequest request) {
if (request.url.contains("mailto:")) {
launch(request.url);
return NavigationDecision.navigate;
}
},
),
)
)
);
}
}
But it is throwing errors like
Error: Not a constant expression.
if (request.url.contains("mailto:")) {

Answer 1

You can copy paste run full code below
Step 1: You can remove const keyword from const WebView
Step 2: You can use NavigationDecision.prevent
working demo
full code
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:url_launcher/url_launcher.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: SafeArea(
child: WebView(
initialUrl:
'https://google.com', //'''https://www.scottseverance.us/mailto.html',
javascriptMode: JavascriptMode.unrestricted,
navigationDelegate: (NavigationRequest request) {
print(request.url);
if (request.url.contains("mailto:")) {
launch(request.url);
return NavigationDecision.prevent;
} else {
return NavigationDecision.navigate;
}
},
),
)));
}
}