This snippet compile successfully but fail in runtime
Map<String, dynamic> queryParameters = {"id": 3};
Map<String, String> stringQueryParameters = Map<String, String>.from(queryParameters);
Uncaught Error: TypeError: 3: type 'int' is not a subtype of type 'String'
What's the proper way to convert from Map<String, dynamic> to Map<String, String> ?
You can use .map to convert your keys:
Map<String, dynamic> queryParameters = {"id": 3};
Map<String, String> stringQueryParameters =
queryParameters.map((key, value) => MapEntry(key, value?.toString()));
Loop all items, call .toString() and store the result as the new value
Map<String, dynamic> queryParameters = {"id": 3, "name": null};
Map<String, String> stringQueryParameters = Map<String, String>();
queryParameters.forEach((key, value) => stringQueryParameters[key] = value?.toString());
// ...
@Mattia's answer didn't work for me. Calling map() returns a Map<dynamic, dynamic>, which is also not a subtype of Map<String, String>.
So in addition to calling map(), I found I needed to call cast().
Map<String, dynamic> queryParameters = {"id": 3};
Map<String, String> stringParameters = queryParameters.map(
(key, value) => key, value?.toString())
).cast<String, String>();
