How do you load array and object from Cloud Firestore in Flutter

Question

I have a class that has several embedded arrays as well as a couple of objects. I'm using Flutter and can't figure out how to read/write to Cloud Firestore.

I can read/write data members that are default types like String and Int. Here is the constructor I'm trying to use to instantiate an object from a DocumentSnapshot:

 class GameReview {
   String name;
   int howPopular;
   List<String> reviewers;
 }

 class ItemCount {
   int itemType;
   int count;

   ItemCount.fromMap(Map<dynamic, dynamic> data)
       : itemType = data['itemType'],
         count = data['count'];
 }

 class GameRecord {
   // Header members
   String documentID;
   String name;
   int creationTimestamp;
   List<int> ratings = new List<int>();
   List<String> players = new List<String>();
   GameReview gameReview;
   List<ItemCount> itemCounts = new List<ItemCount>();

   GameRecord.fromSnapshot(DocumentSnapshot snapshot)
       : documentID = snapshot.documentID,
         name = snapshot['name'],
         creationTimestamp = snapshot['creationTimestamp'],
         ratings = snapshot['ratings'], // ERROR on run
         players = snapshot['players'], // ERROR on run
         gameReview = snapshot['gameReview']; // ERROR on run
         itemCount = ????
 }

It works until I add the last 3 members (ratings, players and gameReview). This should be obvious but none the less, it eludes me.

Help!

UPDATE: Here is a sample of the document stored in Cloud Firestore. This is stored in a single document. In other words, I'm not using sub-collections for the embedded objects. I put it into a JSON format for clarity. I hope this helps.

 {
   "documentID": "asd8didjeurkff3",
   "name": "My Game Record",
   "creationTimestamp": 1235434,
   "ratings": [
     4,
     2012,
     4
   ],
   "players": [
     "Fred",
     "Sue",
     "John"
   ],
   "gameReview": {
     "name": "Review 1",
     "howPopular": 5,
     "reviewers": [
       "Bob",
       "Hanna",
       "George"
     ]
   },
  "itemCounts": [
     {
       "itemType": 2,
       "count": 3
     },
     {
       "itemType": 1,
       "count": 2
     }
   ]
 }

UPDATE 2: I didn't put in the whole class definition because I thought it would be obvious to me how to do the rest but alas that was not the case.

I have a list of objects that I want to load.vbandrade's answer is BANG on but I can't quite figure out how I'm supposed to create the list of objects. List.from(...) is looking for an iterator, not a created class. I'm sure it's some variation of creating a new object and then adding it to a list but I'm a little confused. (see edits in class above, specifically, the "itemCounts" member.

Answer 1

Waitting for answers