Flutter Firebase upload a List of customClass - list

Question

I want to upload a List of a custom class to the cloud firebase, but I get the error that my custom class is not a subtype of type <dynamic>. Does this happen because it is not possible to upload List of custom classes to firebase? Do I need to create e new collection which than works as the List or is there a other way to work around this problem?
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
//Class for the custom list
class CustomClass {
int id;
String content;
CustomClass({this.id, this.content});
CustomClass.fromMap(Map<String, dynamic> data) {
id = data['id'];
content = data['content'];
}
Map<String, dynamic> toMap() {
return {
'id': id,
'content': content,
};
}
}
//Model which I want to upload with the custom list
class CustomModel {
String name;
List<CustomClass> customList;
CustomModel();
CustomModel.fromMap(Map<String, dynamic> data) {
name = data['name'];
customList = data['customList'];
}
Map<String, dynamic> toMap() {
return {
'name': name,
'customList': customList,
};
}
}
//Page to upload the customModel with the customList
class UploadPage extends StatelessWidget {
CustomModel _customModel = CustomModel();
List<CustomClass> _customList = [CustomClass(id: 1, content: 'UserContent')];
#override
Widget build(BuildContext context) {
return Scaffold(
body: FlatButton(
child: Text('Upload'),
onPressed: () async {
_customModel.name = 'UserName';
_customModel.customList = _customList;
await Firestore.instance
.collection('CustomClass')
.add(_customModel.toMap());
}),
);
}
}

Answer 1

You can use dart: convert to convert your model object into json format i.e Map which you can upload to Firebase.
For this, I have renamed your toMap method to toJson & fromMap methods to fromJson. Also, I have added factory keyword before fromJson methods.
You should also override the toString method to print your objects for testing/debugging.
Your code should look something like this:
//Class for the custom list
class CustomClass {
int id;
String content;
CustomClass({this.id, this.content});
factory CustomClass.fromJson(Map<String, dynamic> data) {
return CustomClass(
id: data['id'],
content: data['content'],
);
}
Map<String, dynamic> toJson() {
return {
'id': id,
'content': content,
};
}
#override
String toString() {
return '${const JsonEncoder.withIndent(' ').convert(this)}';
}
}
//Model wich I want to upload with the custom list
class CustomModel {
String name;
List<CustomClass> customList;
CustomModel({
this.name,
this.customList,
});
factory CustomModel.fromJson(Map<String, dynamic> data) {
List<dynamic> list = data['customList'] ?? [];
final customList = list.map((e) => CustomClass.fromJson(e)).toList();
return CustomModel(
name: data['name'],
customList: customList,
);
}
Map<String, dynamic> toJson() {
return {
'name': name,
'customList': customList?.map((e) => e.toJson())?.toList(),
};
}
#override
String toString() {
return '${const JsonEncoder.withIndent(' ').convert(this)}';
}
}
// Your build method:
CustomModel _customModel = CustomModel();
List<CustomClass> _customList = [CustomClass(id: 1, content: 'UserContent')];
#override
Widget build(BuilContext context) {
return Scaffold(
body: FlatButton(
child: Text('Upload'),
onPressed: () async {
_customModel.name = 'UserName';
_customModel.customList = _customList;
await Firestore.instance
.collection('CustomClass')
.add(_customModel.toJson());
}),
);
}