Dart maps, how to replace specific key value in a list<map> based on its key id?

You can try something like this:

   products.where((x) => x["id"] == 48).first["time"] = "2019-10-26 00:00:00.000";

Here is another way how you can do it:

    void main() { 
      List<Map<String, dynamic>> products = [
        {'id': 24, 'time': '2019-11-24 00:00:00.000'},
        {'id': 36, 'time': '2019-11-23 00:00:00.000'},
        {'id': 48, 'time': '2019-11-24 00:00:00.000'},
      ];
      
       products = products.map((product){
        if(product["id"] == 48){
          return {...product, 'time': '2019-10-26 00:00:00.000'};
        }
         return product;
      }).toList();
      
      print(products.toString());
    }