dart_sqflite_json_exam

db_helper.dart

//lib/sqlite/db_helper.dart


import 'dart:io';

import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';

import 'models/dog_model.dart';

final String TableName = 'Dog';

class DBHelper {

  DBHelper._();
  static final DBHelper _db = DBHelper._();
  factory DBHelper() => _db;

  static Database _database;

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

    _database = await initDB();
    return _database;
  }

  initDB() async {
    Directory documentsDirectory = await getApplicationDocumentsDirectory();
    String path = join(documentsDirectory.path, 'MyDogsDB.db');

    return await openDatabase(
      path,
      version: 1,
      onCreate: (db, version) async {
        await db.execute('''
          CREATE TABLE $TableName(
            id INTEGER PRIMARY KEY,
            name TEXT,
          )
        ''');
      },
      onUpgrade: (db, oldVersion, newVersion){}
    );
  }

  //Create
  createData(Dog dog) async {
    final db = await database;
    var res = await db.insert(TableName, dog.toJson());
    return res;
  }

  //Read
  getDog(int id) async {
    final db = await database;
    var res = await db.query(TableName, where: 'id = ?', whereArgs: [id]);
    return res.isNotEmpty ? Dog.fromJson(res.first) : Null;
  }

  //Read All
  Future<List<Dog>> getAllDogs() async {
    final db = await database;
    var res = await db.query(TableName);
    List<Dog> list = res.isNotEmpty ? res.map((c) => Dog.fromJson(c)).toList() : [];
    return list;
  }

  //Update
  updateDog(Dog dog) async {
    final db = await database;
    var res = db.update(TableName, dog.toJson(), where: 'id = ?', whereArgs: [dog.id]);
    return res;
  }

  //Delete
  deleteDog(int id) async {
    final db = await database;
    var res = db.delete(TableName, where: 'id = ?', whereArgs: [id]);
    return res;
  }

  //Delete All
  deleteAllDogs() async {
    final db = await database;
    db.rawDelete('DELETE FROM $TableName');
  }

}

dog_model.dart

//lib/sqlite/models/dog_model.dart

class Dog {
  final int id;
  final String name;

  Dog({this.id, this.name});

  factory Dog.fromJson(Map<String, dynamic> json) => Dog(
    id: json["id"],
    name: json["name"]
  );

  Map<String, dynamic> toJson() => {
    "id":id,
    "name":name,
  };
}

main.dart

//lib/main.dart

import 'package:flutter/material.dart';

import 'sqlite/db_helper.dart';
import 'sqlite/models/dog_model.dart';
import 'dart:math';


List<Dog> dogs = [
  Dog(name: '푸들이'),
  Dog(name: '삽살이'),
  Dog(name: '말티말티'),
  Dog(name: '강돌이'),
  Dog(name: '진져'),
  Dog(name: '백구'),
];

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Dog Database'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: FutureBuilder(
        future: DBHelper().getAllDogs(),
        builder: (BuildContext context, AsyncSnapshot<List<Dog>> snapshot) {

          if(snapshot.hasData) {
            return ListView.builder(
              itemCount: snapshot.data.length,
              itemBuilder: (BuildContext context, int index) {
                Dog item = snapshot.data[index];
                return Dismissible(
                  key: UniqueKey(),
                  onDismissed: (direction) {
                    DBHelper().deleteDog(item.id);
                  },
                  child: Center(child: Text(item.name)),
                );
              },
            );
          }
          else
          {
            return Center(child: CircularProgressIndicator(),);
          }
        },
      ),

      floatingActionButton: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          FloatingActionButton(
            child: Icon(Icons.refresh),
            onPressed: () {
              DBHelper().deleteAllDogs();
              setState(() {});
            },
          ),
          SizedBox(height: 8.0),
          FloatingActionButton(
            child: Icon(Icons.add),
            onPressed: () {
              Dog dog = dogs[Random().nextInt(dogs.length)];
              DBHelper().createData(dog);
              setState(() {});
            },
          ),
        ],
      )

    );
  }
}