Flutter Error: The argument type ‘String’ can’t be assigned to the parameter type ‘Uri’

If you’re using the http package (version 0.13 or newer), you might run into the following error when sending HTTP requests:

The argument type 'String' can't be assigned to the parameter type 'Uri'

The cause of this error is that the functions provided by the http package previously received arguments with both String and Uri types, but now it only accepts Uri types.

Let’s Fix It

You can fix the mentioned issue with one line of code. By using the Uri.parse() method, you can create a new Uri object by parsing a URI string.

Example:

import 'package:http/http.dart' as http;

/* ... */
void _sendPostRequest() async {
    try {
      const String apiEndpoint =
          'https://api.kindacode.com/this-is-a-fiction-api-endpoint'; 
      // Replace with your own api url

      final Uri url = Uri.parse(apiEndpoint);
      final response = await http.post(url);

      // Do something with the response
      print(response);
    } catch (err) {
      // Handling error
      print(err);
    }
}

Note that the Uri class comes with dart:core so you can use it right away.

Further reading:

• 2 Ways to Fetch Data from APIs in Flutter
• Best Libraries for Making HTTP Requests in Flutter
• Flutter and Firestore Database: CRUD example (null safety)
• Using GetX (Get) for Navigation and Routing in Flutter
• Using GetX (Get) for State Management in Flutter
• Flutter + Firebase Storage: Upload, Retrieve, and Delete files

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