SQFLite (Flutter) Insert fails for Map containing Maps - flutter

Question

Can someone confirm if SQFLite supports maps containing maps? I did run across the following post on this site and possibly this is the answer?
Flutter sqflite insert List<String>
In my situation, I have a two model classes I am working with.
House
Dog
House includes a field called pets which is a List
I have a constructor and factory method in each of these classes which takes care of converting to/from map/object as needed for sending to and retrieving information from SQFLite.
Model classes
Dog
class Dog {
final int id;
final String breed;
final String name;
final int age;
Dog({this.id, this.breed, this.name, this.age});
// Used when inserting a row into the db, including the id field
Map<String, dynamic> toMap() {
final map = Map<String, dynamic>();
map['id'] = id;
map['breed'] = breed;
map['name'] = name;
map['age'] = age;
return map;
}
// Used when returning a row from the DB and converting into an object
factory Dog.fromMap(Map<String, dynamic> data) => Dog(
id: data['id'],
breed: data['breed'],
name: data['name'],
age: data['age']
);
}
House
import 'dog.dart';
class House{
final int id;
final String name;
final String color;
final List<Dog> pets;
House({this.id, this.name, this.color, this.pets});
// Will be used when inserting a row into the database
Map<String, dynamic> toMap() {
final map = Map<String, dynamic>();
map['id'] = id;
map['name'] = name;
map['color'] = color;
if (this.pets != null) {
map['pets'] = this.pets.map((pet) => pet.toMap()).toList();
}
return map;
}
// Used when returning a row from the DB and converting into an object
factory House.fromMap(Map<String, dynamic> data) {
return House(
id: data['id'],
name: data['name'],
color: data['color'],
pets: data['pets'] != null
? (data['pets'] as List).map((pet) => Dog.fromMap(pet)).toList()
: null,
);
}
}
Method for inserting a new house
Future<int> addNewHome(House house) async {
// Attempt to add the house to the DB
var client = await database.db;
int result = await client.insert(HomesSchema.tblHomes, house.toMap(), conflictAlgorithm: ConflictAlgorithm.replace);
_homes.add(house);
return result;
}
When I attempt to perform the insert, I get the following error.
E/flutter ( 586): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: DatabaseException(java.util.HashMap cannot be cast to java.lang.Integer) sql 'INSERT OR REPLACE INTO homes (id, name, color, pets) VALUES (?, ?, ?, ?)' args [1, Smith, Green, [{name: Mackie, id: 1, breed: Rottweiler, age: 8}, {name: Tanner, id: 2, breed: Mastiff, age: 8}]]}
E/flutter ( 586): #0 wrapDatabaseException (package:sqflite/src/exception_impl.dart:12:7)
E/flutter ( 586): <asynchronous suspension>
E/flutter ( 586): #1 SqfliteDatabaseFactoryImpl.wrapDatabaseException (package:sqflite/src/factory_impl.dart:25:7)
E/flutter ( 586): #2 SqfliteDatabaseMixin.safeInvokeMethod (package:sqflite/src/database_mixin.dart:188:15)
E/flutter ( 586): #3 SqfliteDatabaseMixin.txnRawInsert.<anonymous closure> (package:sqflite/src/database_mixin.dart:363:14)
E/flutter ( 586): #4 SqfliteDatabaseMixin.txnSynchronized.<anonymous closure> (package:sqflite/src/database_mixin.dart:307:22)
E/flutter ( 586): #5 BasicLock.synchronized (package:synchronized/src/basic_lock.dart:32:26)
E/flutter ( 586): #6 SqfliteDatabaseMixin.txnSynchronized (package:sqflite/src/database_mixin.dart:303:43)
E/flutter ( 586): #7 SqfliteDatabaseMixin.txnWriteSynchronized (package:sqflite/src/database_mixin.dart:325:7)
E/flutter ( 586): #8 SqfliteDatabaseMixin.txnRawInsert (package:sqflite/src/database_mixin.dart:362:12)
E/flutter ( 586): #9 SqfliteDatabaseExecutorMixin.rawInsert (package:sqflite/src/database_mixin.dart:49:15)
E/flutter ( 586): #10 SqfliteDatabaseExecutorMixin.insert (package:sqflite/src/database_mixin.dart:59:12)
E/flutter ( 586): #11 Homes.addNewHome (package:search_list_view/providers/homes.dart:19:31)
E/flutter ( 586): <asynchronous suspension>
E/flutter ( 586): #12 _MyAppState.build.<anonymous closure> (package:search_list_view/main.dart:95:26)
E/flutter ( 586): #13 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:706:14)
E/flutter ( 586): #14 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:789:36)
E/flutter ( 586): #15 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
E/flutter ( 586): #16 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:486:11)
E/flutter ( 586): #17 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:264:5)
E/flutter ( 586): #18 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:199:7)
E/flutter ( 586): #19 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:467:9)
E/flutter ( 586): #20 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:76:12)
E/flutter ( 586): #21 PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:117:9)
E/flutter ( 586): #22 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:379:8)
E/flutter ( 586): #23 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:115:18)
E/flutter ( 586): #24 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:7)
E/flutter ( 586): #25 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:218:19)
E/flutter ( 586): #26 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22)
E/flutter ( 586): #27 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7)
E/flutter ( 586): #28 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7)
E/flutter ( 586): #29 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7)
E/flutter ( 586): #30 _rootRunUnary (dart:async/zone.dart:1138:13)
E/flutter ( 586): #31 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
E/flutter ( 586): #32 _CustomZone.runUnaryGuarded (dart:async/zone.dart:933:7)
E/flutter ( 586): #33 _invoke1 (dart:ui/hooks.dart:273:10)
E/flutter ( 586): #34 _dispatchPointerDataPacket (dart:ui/hooks.dart:182:5)
E/flutter ( 586):
If the answer is to change my DB schema so I have a table which joins dogs and houses and then do a custom query to pull back the information I'm after, then fine, I will do that. It doesn't seem too far fetch that a nosql db should be able to handle this... yes/no?
Any assistance would be much appreciated.
Thank you,
Bob

Answer 1

For storing any kind of value in the SQLite Database you can simply serialize the object into a JSON string and later deserialize the object.
lets say you have a class called Menu. (I am using JSON serializable here)
class Menu {
#JsonKey(name: "status")
String status;
#JsonKey(name: "data")
MenuListData menuListData;
Menu(this.status, this.menuListData);
factory Menu.fromJson(Map<String,dynamic>
json)=>_$MenuFromJson(json);
Map<String, dynamic> toJson() => _$MenuToJson(this);
}
Here is how to encode it in JSON and store it(in your bloc).
Menue menuList =
await getIt<LiveMenuRepository>().getMenuResponse(menuPost);
//decode the response to String format
String menuResponseString = jsonEncode(menuList);
//convert the string to Map of <String,dynamic> format
Map<String, dynamic> menuResponseMap = {"menu": menuResponseString};
//store this Map response in to local database
int menuStored = await getIt<LocalMenuRepository>().insertMenuResponseData(menuResponseMap);
Your DB insertion method
Future<int> insertMenuResponseData(Map<String,dynamic> menuResponse) async {
final db = await dbProvider.database;
var result = db.insert(menuTable, menuResponse);
return result;
}
Later retrieve your object using this
final Map<String, dynamic> menuList = await getIt<LocalMenuRepository>().getMenuResponseString();
// if(menuList!=null) {
menuList.forEach((key, value) {
if (key == "menu") {
storedMenu = value ;
}
});
//decode the string back to Map Object
final dynamic menuMap = jsonDecode(storedMenu);
//getting the Menu object using fromJson method
final Menu menuListNameResponse = Menu
.fromJson(menuMap as Map<String,dynamic>);
//getMenuResponseString method in db
Future<Map<String,dynamic>> getMenuResponse() async {
final db = await dbProvider.database;
List<Map<String, dynamic>> result;
result = await db.rawQuery('SELECT * FROM $menuTable');
// print(result[0]);
if (result.length > 0) {
return result[0];
}
return null;
}

Answer 2

Supported types are listed here (num, String or Uint8List): https://github.com/tekartik/sqflite/blob/master/sqflite/doc/supported_types.md
Nested content is not supported, Map and List should be encoded in a supported type for example as json string.