New Example - App to store data locally using SQlite (#102)

* Added files of save data locally using sqlite example App

* Update README.md

save_data_locally_with_sqlite/lib/database/database_queries.dart

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+import 'package:save_data_locally_with_sqlite/database/local_database.dart';
+import 'package:sqflite/sqflite.dart';
+
+Future<void> InsertData(String note, String datetime) async {
+  Database? db = await LocalDatabase.instance.database;
+
+  await db!.rawQuery('''
+  INSERT INTO data (datetime,note,timestamp) VALUES ('$datetime','$note',CURRENT_TIMESTAMP)
+  ''');
+}
+
+Future<List<Map>> GetData() async {
+  Database? db = await LocalDatabase.instance.database;
+  List<Map> list = await db!.rawQuery('''
+  SELECT * FROM data ORDER BY timestamp DESC
+  ''');
+  return list;
+}
+
+Future<void> DeleteData(String datetime) async {
+  Database? db = await LocalDatabase.instance.database;
+  await db!.rawQuery('''
+  DELETE FROM data WHERE datetime='$datetime' 
+  ''');
+}

save_data_locally_with_sqlite/lib/database/local_database.dart

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+import 'dart:async';
+import 'dart:io';
+
+import 'package:path/path.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:sqflite/sqflite.dart';
+
+class LocalDatabase {
+  static final _databaseName = "database.db";
+  static final _databaseVersion = 1;
+
+  static Database? _database;
+
+  LocalDatabase._privateConstructor();
+  static final LocalDatabase instance = LocalDatabase._privateConstructor();
+
+  Future<Database?> get database async {
+    if (_database != null)
+      return _database; //if database already present it return the database else create a new one then return it
+    _database = await _initDatabase();
+    return _database;
+  }
+
+  _initDatabase() async {
+    Directory documentsDirectory = await getApplicationDocumentsDirectory();
+    String path = join(documentsDirectory.path, '$_databaseName');
+    return await openDatabase(path, version: _databaseVersion,
+        onCreate: (db, int) async {
+      await db.execute('''
+              CREATE TABLE data (
+              datetime TEXT,
+              note TEXT,
+              timestamp TIMESTAMP
+            )
+           ''');
+    });
+  }
+}

save_data_locally_with_sqlite/lib/main.dart

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+import 'package:flutter/material.dart';
+import 'package:save_data_locally_with_sqlite/screens/homescreen/homescreen.dart';
+
+void main() {
+  runApp(MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  // This widget is the root of your application.
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      home: HomeScreen(),
+    );
+  }
+}

save_data_locally_with_sqlite/lib/screens/homescreen/homescreen.dart

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+import 'package:flutter/material.dart';
+import 'package:save_data_locally_with_sqlite/database/database_queries.dart';
+import 'package:save_data_locally_with_sqlite/screens/homescreen/widgets/note_container.dart';
+
+class HomeScreen extends StatefulWidget {
+  @override
+  _HomeScreenState createState() => _HomeScreenState();
+}
+
+class _HomeScreenState extends State<HomeScreen> {
+  String note = '';
+  List<Map> notes = [];
+  TextEditingController textEditingController = TextEditingController();
+  void AddDatatoDatabase(String note) async {
+    String datetime =
+        '${DateTime.now().day}-${DateTime.now().month}-${DateTime.now().year} ${DateTime.now().hour}:${DateTime.now().minute}:${DateTime.now().second}';
+    await InsertData(note, datetime);
+    UpdateNotesList();
+  }
+
+  void DeleteDataFromDatabase(String datetime) async {
+    print(datetime);
+    await DeleteData(datetime);
+    UpdateNotesList();
+  }
+
+  void UpdateNotesList() async {
+    notes = await GetData();
+    print(notes);
+    setState(() {});
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    print('init');
+    UpdateNotesList();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return SafeArea(
+      child: Scaffold(
+        appBar: AppBar(
+          title: Container(
+            child: Text('Save Data locally using sqlite'),
+          ),
+        ),
+        body: Container(
+          height: double.infinity,
+          width: double.infinity,
+          color: Colors.white,
+          child: Column(
+            children: [
+              Container(
+                height: 140,
+                width: 350,
+                margin: EdgeInsets.only(top: 20),
+                child: Column(
+                  children: [
+                    Container(
+                      child: TextField(
+                        controller: textEditingController,
+                        onChanged: (text) {
+                          note = text;
+                        },
+                        maxLines: 2,
+                        decoration: InputDecoration(
+                          hintText: 'Enter Text',
+                          border: OutlineInputBorder(
+                            borderRadius:
+                                BorderRadius.all(Radius.circular(32.0)),
+                          ),
+                          enabledBorder: OutlineInputBorder(
+                            borderSide: BorderSide(
+                                color: Colors.lightBlueAccent, width: 1.0),
+                            borderRadius:
+                                BorderRadius.all(Radius.circular(32.0)),
+                          ),
+                          focusedBorder: OutlineInputBorder(
+                            borderSide: BorderSide(
+                                color: Colors.lightBlueAccent, width: 2.0),
+                            borderRadius:
+                                BorderRadius.all(Radius.circular(32.0)),
+                          ),
+                        ),
+                      ),
+                    ),
+                    GestureDetector(
+                      onTap: () {
+                        AddDatatoDatabase(note);
+                        textEditingController.clear();
+                        note = '';
+                      },
+                      child: Container(
+                        width: 60,
+                        height: 30,
+                        alignment: Alignment.center,
+                        margin: EdgeInsets.only(top: 10),
+                        decoration: BoxDecoration(
+                            color: Colors.blue,
+                            borderRadius: BorderRadius.circular(10)),
+                        child: Text(
+                          'Add',
+                          style: TextStyle(
+                            color: Colors.white,
+                          ),
+                        ),
+                      ),
+                    )
+                  ],
+                ),
+              ),
+              Expanded(
+                child: ListView.builder(
+                  itemBuilder: (context, index) {
+                    return GestureDetector(
+                      onLongPress: () {
+                        DeleteDataFromDatabase(notes[index]['datetime']);
+                      },
+                      child: NoteContainer(
+                        text: notes[index]['note'],
+                        datetime: notes[index]['datetime'],
+                      ),
+                    );
+                  },
+                  itemCount: notes.length,
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}

save_data_locally_with_sqlite/lib/screens/homescreen/widgets/note_container.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter/painting.dart';
+
+class NoteContainer extends StatelessWidget {
+  final String text;
+  final String datetime;
+  NoteContainer({Key? key, this.text = '', this.datetime = ''})
+      : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      margin: EdgeInsets.symmetric(vertical: 7, horizontal: 20),
+      decoration: BoxDecoration(
+        borderRadius: BorderRadius.circular(15),
+        boxShadow: [
+          BoxShadow(
+            color: Colors.blue.withOpacity(.4),
+            spreadRadius: 2.5,
+            blurRadius: 2.5,
+          )
+        ],
+        color: Colors.white,
+      ),
+      child: Column(
+        children: [
+          Container(
+            alignment: Alignment.center,
+            child: Text(
+              '$datetime',
+              style: TextStyle(
+                color: Colors.grey.shade700,
+                fontSize: 12,
+              ),
+            ),
+          ),
+          Row(
+            crossAxisAlignment: CrossAxisAlignment.center,
+            children: [
+              Flexible(
+                child: Container(
+                  padding: EdgeInsets.symmetric(vertical: 5, horizontal: 10),
+                  child: Text(
+                    '$text',
+                  ),
+                ),
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}