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Adding null safety #15

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203 changes: 96 additions & 107 deletions lib/utils/database_helper.dart
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Original file line number Diff line number Diff line change
@@ -1,113 +1,102 @@
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart';
import 'dart:async';
import 'dart:io';
import 'package:path_provider/path_provider.dart';
import 'package:flutter_app/models/note.dart';
import 'package:flutter_codes/models/note.dart';

class DatabaseHelper {

static DatabaseHelper _databaseHelper; // Singleton DatabaseHelper
static Database _database; // Singleton Database

String noteTable = 'note_table';
String colId = 'id';
String colTitle = 'title';
String colDescription = 'description';
String colPriority = 'priority';
String colDate = 'date';

DatabaseHelper._createInstance(); // Named constructor to create instance of DatabaseHelper

factory DatabaseHelper() {

if (_databaseHelper == null) {
_databaseHelper = DatabaseHelper._createInstance(); // This is executed only once, singleton object
}
return _databaseHelper;
}

Future<Database> get database async {

if (_database == null) {
_database = await initializeDatabase();
}
return _database;
}

Future<Database> initializeDatabase() async {
// Get the directory path for both Android and iOS to store database.
Directory directory = await getApplicationDocumentsDirectory();
String path = directory.path + 'notes.db';

// Open/create the database at a given path
var notesDatabase = await openDatabase(path, version: 1, onCreate: _createDb);
return notesDatabase;
}

void _createDb(Database db, int newVersion) async {

await db.execute('CREATE TABLE $noteTable($colId INTEGER PRIMARY KEY AUTOINCREMENT, $colTitle TEXT, '
'$colDescription TEXT, $colPriority INTEGER, $colDate TEXT)');
}

// Fetch Operation: Get all note objects from database
Future<List<Map<String, dynamic>>> getNoteMapList() async {
Database db = await this.database;

// var result = await db.rawQuery('SELECT * FROM $noteTable order by $colPriority ASC');
var result = await db.query(noteTable, orderBy: '$colPriority ASC');
return result;
}

// Insert Operation: Insert a Note object to database
Future<int> insertNote(Note note) async {
Database db = await this.database;
var result = await db.insert(noteTable, note.toMap());
return result;
}

// Update Operation: Update a Note object and save it to database
Future<int> updateNote(Note note) async {
var db = await this.database;
var result = await db.update(noteTable, note.toMap(), where: '$colId = ?', whereArgs: [note.id]);
return result;
}

// Delete Operation: Delete a Note object from database
Future<int> deleteNote(int id) async {
var db = await this.database;
int result = await db.rawDelete('DELETE FROM $noteTable WHERE $colId = $id');
return result;
}

// Get number of Note objects in database
Future<int> getCount() async {
Database db = await this.database;
List<Map<String, dynamic>> x = await db.rawQuery('SELECT COUNT (*) from $noteTable');
int result = Sqflite.firstIntValue(x);
return result;
}

// Get the 'Map List' [ List<Map> ] and convert it to 'Note List' [ List<Note> ]
Future<List<Note>> getNoteList() async {

var noteMapList = await getNoteMapList(); // Get 'Map List' from database
int count = noteMapList.length; // Count the number of map entries in db table

List<Note> noteList = List<Note>();
// For loop to create a 'Note List' from a 'Map List'
for (int i = 0; i < count; i++) {
noteList.add(Note.fromMapObject(noteMapList[i]));
}

return noteList;
}

static DatabaseHelper? _databaseHelper;
static Database? _database;

String noteTable = 'note_table';
String colId = 'id';
String colTitle = 'title';
String colDescription = 'description';
String colPriority = 'priority';
String colDate = 'date';

DatabaseHelper._createInstance();

factory DatabaseHelper() {
if (_databaseHelper == null) {
_databaseHelper = DatabaseHelper._createInstance();
}
return _databaseHelper!;
}

Future<Database> get database async {
if (_database == null) {
_database = await initializeDatabase();
}
return _database!;
}

Future<Database> initializeDatabase() async {
Directory directory = await getApplicationDocumentsDirectory();
String path = directory.path + 'notes.db';

var notesDatabase = await openDatabase(
path,
version: 1,
onCreate: _createDb,
);
return notesDatabase;
}

void _createDb(Database db, int newVersion) async {
await db.execute(
'CREATE TABLE $noteTable($colId INTEGER PRIMARY KEY AUTOINCREMENT, $colTitle TEXT, '
'$colDescription TEXT, $colPriority INTEGER, $colDate TEXT)');
}

// Fetch Operation
Future<List<Map<String, dynamic>>> getNoteMapList() async {
Database db = await this.database;
var result = await db.query(noteTable, orderBy: '$colPriority ASC');
return result;
}

// Insert
Future<int> insertNote(Note note) async {
Database db = await this.database;
var result = await db.insert(noteTable, note.toMap());
return result;
}

// Update
Future<int> updateNote(Note note) async {
Database db = await this.database;
var result = await db.update(noteTable, note.toMap(),
where: '$colId = ?', whereArgs: [note.id]);
return result;
}

// Delete
Future<int> deleteNote(int id) async {
Database db = await this.database;
var result =
await db.rawDelete('DELETE FROM $noteTable WHERE $colId = $id');
return result;
}

// count
Future<int> getCount() async {
Database db = await this.database;
List<Map<String, dynamic>> x =
await db.rawQuery('SELECT COUNT (*) FROM $noteTable');
int? result = Sqflite.firstIntValue(x);
return result!;
}

Future<List<Note>> getNoteList() async {
var noteMapList = await getNoteMapList();
int count = noteMapList.length;

List<Note> noteList = [];
for (int i = 0; i < count; i++) {
noteList.add(Note.fromMapObject(noteMapList[i]));
}

return noteList;
}
}