Recently I moved one of my flutter app to web. It was working fine when I started from my main url. It was hash driven. But as soon as I started providing direct urls, the web app started showing 404 errors. In this article we will solve this issue by configuring our app for path driven URL Strategies.
Types of URL Navigations for Flutter Web
Flutter web apps support two ways of configuring URL-based navigation on the web:
Hash (default)
Paths are read and written to the hash fragment. For example, flutterexample.dev/#/path/to/screen.
Path
Paths are read and written without a hash. For example, flutterexample.dev/path/to/screen.
Configuring the URL strategy
To configure Flutter to use the path instead, use the setUrlStrategy function provided by the flutter_web_plugins library in the SDK.
The setUrlStrategy API can only be called on the web. The following instructions show how to use a conditional import to call this function on the web, but not on other platforms.
Note: By default, Flutter uses the hash (/#/) location strategy. These instructions are only required if you want to use the URL path strategy.
Web Plugin setup
First, add flutter_web_plugins to your pubspec.yaml:
dependencies:
flutter_web_plugins:
sdk: flutter
Then call setUrlStrategy before runApp():
import 'package:flutter/material.dart';
import 'package:flutter_web_plugins/flutter_web_plugins.dart';
void main() {
setUrlStrategy(PathUrlStrategy());
runApp(MyApp());
}
#Cross Platform setup
If your app is cross-platform, use Dart’s conditional imports feature by creating three files:
url_strategy.dart
export 'url_strategy_noop.dart' if (dart.library.html) 'url_strategy_web.dart';
url_strategy_noop.dart
void usePathUrlStrategy() {
}
url_strategy_web.dart
import 'package:flutter_web_plugins/flutter_web_plugins.dart';
void usePathUrlStrategy() {
setUrlStrategy(PathUrlStrategy());
}
Then, call setPathUrlStrategy before runApp():
main.dart
import 'package:flutter/material.dart';
import 'url_strategy.dart';
void main() {
usePathUrlStrategy();
runApp(MyApp());
}
Using conditional imports ensures that the flutter_web_plugins library is only loaded when your app is running on the web.
Configuring your web server
The local dev server created by running flutter run -d chrome is configured to handle any path gracefully and fallback to your app’s index.html file.
To configure your web server to support PathUrlStrategy you will need add some rewrite rules to your htaccess file.
.htaccess
RewriteEngine On
RewriteBase /
RewriteRule ^index.html$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.html [L]
Whats Next
In this article I have given your the minimal steps required to configure your web app and the web server for URL Path based navigation. We can extend it as per our requirement so that it can even support forward and backward in browsers. Please share how you implemented URL strategies in your flutter web app.
Reference:
https://docs.flutter.dev/development/ui/navigation/url-strategies
