breaking exception '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'Map<String, String>'
The constructor for Uri.https requires a Map with a runtime type of Map<String, String>. When you create stringParams without any type annotations, you are actually creating a Map<dynamic, dynamic>. The correct way to create this for Dart 2 is
Map<String, String> stringParams = {};// orvar stringParams = <String, String>{};The reason this used to work is that in Dart 1, even in strong mode, dynamic was fuzzy and acted like both Object and null - meaning a dynamic type was assignable to and from anything. In Dart 2, dynamic acts just like Object, except you can call methods or access properties on it without a downcast.
I used this
if(json["key"]!= null){ this.active_guests = json["key"].cast<String, int>(); }
You can send nested JSON params like this:
Convert it to a string using
json.encode.Send "Content-Type:application/json" in header.
var uri = "${Config.baseURL}/your/endpoint";var headers = { 'Content-Type': 'application/json'};final response = await http.post( uri, body: json.encode(data), headers: headers);