How can I insert the List in a column of sqflite database

I am working on a flutter project where I have two databases, firestore database as online database and sqflite database as localdatabase.

What I am trying to do is that when the user starts the application, it will get a collection of recipes from firestore database and store it locally in sqflite database.

Here is the function:

Future<List> getRecipeDataList() async {
    List recipes = [];
    int count =  await getRecipeCount();
    int recipeID = 101;
    for (int i = 0; i < count; i++, recipeID++) {
      if (await checkIfRecipeDocExists(recipeID.toString()) ==
          true) {
        QuerySnapshot<Map<String, dynamic>> recipesSnapshot = await FirebaseFirestore.instance.collection('recipes').get();
        for(QueryDocumentSnapshot<Map<String, dynamic>> doc in recipesSnapshot.docs){
          final data = doc.data();
          await LocalDatabase.instance.insertRecipe({
            LocalDatabase.recipeID: 100,
            LocalDatabase.recipe_name: data['recipe_name'],
            LocalDatabase.recipe_description: data['recipe_description'],
            LocalDatabase.recipeImageURL: data['recipeImageURL'],
            LocalDatabase.recipe_rating: data['recipe_rating'],
            LocalDatabase.recipe_time: data['recipe_time'],
            LocalDatabase.recipe_ingredients: data['recipe_ingredients'],
          });
          recipes.add(
            Recipes(
              recipeID: doc.id,
              recipeName: data['recipe_name'],
              recipeDescription: data['recipe_description'],
              recipeURL: data['recipeImageURL'],
              recipeRating: data['recipe_rating'],
              recipeTime: data['recipe_time'],
              recipeIngredients: (data['recipe_ingredients'] as List<dynamic>).cast<String>(),
            ),
          );
        }
      }
    }
    return recipes;
  }

This is my sqflite database class:

import 'dart:io';
import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
class LocalDatabase {
  //variables
  static const dbName = 'localDatabase.db';
  static const dbVersion = 1;
  static const recipeTable = 'recipes';
  static const recipe_description = 'recipe_description';
  static const recipe_rating = 'recipe_rating';
  static const recipeImageURL = 'recipeImageURL';
  static const recipe_time = 'recipe_time';
  static const recipe_ingredients = 'recipe_ingredients';
  static const recipe_name = 'recipe_name';
  static const recipeID = 'recipeID';
  static const recipe_category = 'recipe_category';

  //Constructor
  static final LocalDatabase instance = LocalDatabase();

  //Initialize Database
  static Database? _database;

  Future<Database?> get database async {
    _database ??= await initDB();
    return _database;
  }

  initDB() async {
    Directory directory = await getApplicationDocumentsDirectory();
    String path = join(directory.path, dbName);
    return await openDatabase(path, version: dbVersion, onCreate: onCreate);
  }

  Future onCreate(Database db, int version) async {
    db.execute('''
      CREATE TABLE $recipeTable (
        $recipeID INTEGER,
        $recipe_name TEXT,
        $recipe_description TEXT,
        $recipe_ingredients TEXT,
        $recipeImageURL TEXT,
        $recipe_category TEXT,
        $recipe_time TEXT,
        $recipe_rating TEXT,
      )
      ''');
  }

  insertRecipe(Map<String, dynamic> row) async {
    Database? db = await instance.database;
    return await db!.insert(recipeTable, row);
  }

  Future<List<Map<String, dynamic>>> readRecipe() async {
    Database? db = await instance.database;
    return await db!.query(recipeTable);
  }

  Future<int> updateRecipe(Map<String, dynamic> row) async {
    Database? db = await instance.database;
    int id = row[recipeID];
    return await db!
        .update(recipeTable, row, where: '$recipeID = ?', whereArgs: [id]);
  }

  Future<int> deleteRecipe(int id) async {
    Database? db = await instance.database;
    return await db!.delete(recipeTable, where: 'recipeID = ?', whereArgs: [id]);
  }
}

Error I am getting is:

> I/flutter (13393): *** WARNING *** I/flutter (13393): I/flutter
> (13393): Invalid argument [Ingredients 1, Ingredients 2, Ingredients
> 3] with type List<dynamic>. I/flutter (13393): Only num, String and
> Uint8List are supported. See
> https://github.com/tekartik/sqflite/blob/master/sqflite/doc/supported_types.md
> for details I/flutter (13393): I/flutter (13393): This will throw an
> exception in the future. For now it is displayed once per type.
> I/flutter (13393): I/flutter (13393): E/flutter (13393):
> [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled
> Exception: DatabaseException(java.lang.String cannot be cast to
> java.lang.Integer) sql 'INSERT INTO recipes (recipeID, recipe_name,
> recipe_description, recipeImageURL, recipe_rating, recipe_time,
> recipe_ingredients) VALUES (?, ?, ?, ?, ?, ?, ?)' args [100,
> recipe_name, recipe_description, recipeImageURL, recipe_rating,
> recipe_time, [Ingredients 1, Ingredients 2, Ingredients 3]] E/flutter
> (13393): #0 wrapDatabaseException
> (package:sqflite/src/exception_impl.dart:11:7) E/flutter (13393):
> <asynchronous suspension> E/flutter (13393): #1
> SqfliteDatabaseMixin.txnRawInsert.<anonymous closure>
> (package:sqflite_common/src/database_mixin.dart:548:14) E/flutter
> (13393): <asynchronous suspension> E/flutter (13393): #2
> BasicLock.synchronized
> (package:synchronized/src/basic_lock.dart:33:16) E/flutter (13393):
> <asynchronous suspension> E/flutter (13393): #3
> SqfliteDatabaseMixin.txnSynchronized
> (package:sqflite_common/src/database_mixin.dart:489:14) E/flutter
> (13393): <asynchronous suspension> E/flutter (13393): #4
> LocalDatabase.insertRecipe
> (package:recipedia/WidgetsAndUtils/local_database.dart:56:12)
> E/flutter (13393): <asynchronous suspension> E/flutter (13393): #5
> RecipeModel.getRecipeDataList
> (package:recipedia/WidgetsAndUtils/recipe_model.dart:78:11) E/flutter
> (13393): <asynchronous suspension> E/flutter (13393): #6
> _LoginState.getRecipeData (package:recipedia/RegistrationAndLogin/login.dart:194:15) E/flutter
> (13393): <asynchronous suspension> E/flutter (13393):

After reading this error, the problems I can identify is that the recipe_ingredient in firestore database is an array and sqflite doesn't support it. How can I resolve this issue?

If you follow the link reported in the log: https://github.com/tekartik/sqflite/blob/master/sqflite/doc/supported_types.md

it will give you some solutions.

One solution would be to encode the recipe_ingredient list from Firestore as a json string that you save in SQLite.

i.e.

instead of

recipeIngredients: (data['recipe_ingredients'] as List<dynamic>).cast<String>(),

try (well maybe you should handle the null value too):

recipeIngredients: jsonEncode(data['recipe_ingredients'])

</details>