Const variables must be initialized with a constant value

I get this error:

Const variables must be initialized with a constant value.
Try changing the initializer to be a constant expression

My code:

  Future<void> _fetchData(String city) async {
    const apiURL =
        'http://api.weatherapi.com/v1/current.json?key=(secret)=$city&aqi=no';

I get the error at the $city

Anyone can help?

CodePudding user response：

here you esentially doing string interpolation, hence your apiURL is dynamic, not const. use final instead

Future<void> _fetchData(String city) async {
    final apiURL =
        'http://api.weatherapi.com/v1/current.json?key=(secret)=$city&aqi=no';

CodePudding user response：

Since you are using $city (which receives the data from the argument), you can no longer define it as a const.

const variables are those whose values are pre-determined and do not change over time. e.g., http://api.weatherapi.com/v1/current.json can be a const but http://api.weatherapi.com/v1/current.json?key=(secret)=$city&aqi=no cannot be a const.

Simply use final (recommended) or var and It should work just fine.