flutter parsing JSON from firebase

Question

I just started learning about flutter and try to use ScopedModel and I get stuck at parsing JSON, everything works until I try to get List of detail simulation but everything that I try just fails

this is my class for project and simulation

 class Project {
  String idProject;
 List images;
 List<Simulations> simulation;     
  Project({
    @required this.idProject,
    @required this.images,
    @required this.simulation

});
}

class Simulations{
  String period;
  int profitProject;
  int roi;

  Simulations({
    @required this.period,
    @required this.profitProject,
    @required this.roi
});

}

I made a separate class to get detail for simulation

this is a sample from JSON that I get from the firebase

{
    "1554182068913": {

        "idProject": "project id 1",
        "images": [
            1554181958565,
            1554181955542,
            1554181960876],

        "simulation": [
                {
                "periode": "year 1",
                "profitProject": 300000,
                "roi": 5,
                "uniqueKey": "YyCWbHjvm"
                }, 

                {
                "periode": "year 1",
                "profitProject": 100000,
                "roi": 3,
                "uniqueKey": "CvyU4SjrX"
                }, 
                {
                "periode": "year 1",
                "profitProject": 2000000,
                "roi": 10,
                "uniqueKey": "Tb_Qr5CIA"
                }
        ],
        }
        }

I made function to get the data

Future<Null> fetchProjects() {
    return http.get("JSON link")
        .then<Null>((http.Response response) {
      final List<Project> fetchedProjectList = [];
      final Map<String, dynamic> projectListData = json.decode(response.body);

      if (projectListData == null) {
        _isLoading = false;
        notifyListeners();
        return;
      }

      projectListData.forEach((String projectId, dynamic projectData) {

        final Project project = Project(
          title: projectData['title'],
          location: projectData['location'],
          images: projectData['images'],
          simulation: ???


        );
        fetchedProjectList.add(project);
        }

Answer 1

What's missing here is JSON serialization. You need to convert the response to a Dart object, similar to what has been demonstrated on this guide. In Project class, you can add a fromJson() constructor to map the data.

factory Project.fromJson(Map<String, dynamic> json) {
  return Project(
    idProject: json['idProject'],
    images: json['images'],
    simulation: json['simulation'],
  );
}