How to copy database from assets list in flutter. If we have an existing database file, that we need to copy into current flutter application.
To read an existing database we will do following steps.
Read create simple Sqflite database in flutter
Let's get started
Step 1: Create a Flutter application
Step 2: Add sqflite dependency plugin in pubspec.yaml file
dependencies:
flutter:
sqflite:
path:
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Step 3: Create a file databse.dart and add below code
This code will check existing database is available or not, if it there it won't create again, if the database is not exist, will read database file from assets file and create database.
Future<String> initDatabase() async {
var databasesPath = await getDatabasesPath();
var path = join(databasesPath, "demo_asset_example.db");
// Check if the database exists
var exists = await databaseExists(path);
if (!exists) {
// Should happen only the first time you launch your application
print("Creating new copy from asset");
// Make sure the parent directory exists
try {
await Directory(dirname(path)).create(recursive: true);
} catch (_) {}
// Copy from asset
ByteData data = await rootBundle.load(join("assets", "example.db"));
List<int> bytes =
data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
// Write and flush the bytes written
await File(path).writeAsBytes(bytes, flush: true);
} else {
print("Reading Existing Database");
}
// open the database
// database = await openDatabase(path, readOnly: true);
return path;
}
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Read database tables from Sqflite database
To read created tables from database we will use below code
Future<String> readTables() async
{
Database db = await database;
var res=await db.rawQuery("select * FROM sqlite_master WHERE type ='table'");
if(res.length>0)
{
return res.first.entries.toString();
}
return "No Tables found";
}
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Complete example to read database from assets file here
import 'dart:async';
import 'package:flutter/material.dart';
import 'databse.dart';
class AssetsDatabase extends StatefulWidget{
@override
_AssetsDatabaseState createState() => _AssetsDatabaseState();
}
class _AssetsDatabaseState extends State<AssetsDatabase> {
bool readTable=false;
String table_info="";
final _tables = StreamController<String>();
Sink get updateUser => _tables.sink;
Stream<String> get user => _tables.stream;
@override
Widget build(BuildContext context) {
// TODO: implement build
return MaterialApp(home: Scaffold(
appBar: AppBar(title: Text("Read Assets Database"),),
body:
Column(
children: [
FutureBuilder(
builder:(context, snapshot) {
if (snapshot.hasData) {
return SingleChildScrollView(
child: Card(
margin: EdgeInsets.all(8),
child: Column(
mainAxisSize: MainAxisSize.max,
children: [
Text("Database Created, Now you can load tables"),
RaisedButton(onPressed: (){
readTable=true;
readTablesFromDb();
},child: Text("Load Tables"),
),
stream(),
],
),
),
);
}
else{
return Text("Database Not created");
}
} ,
future: initDatabase(),
),
],
),
),);
}
stream()
{
return StreamBuilder<String>(
initialData: "",
stream: _tables.stream,
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.active)
return Text(" ${snapshot.data}");
if (snapshot.connectionState == ConnectionState.active)
return Text(" ${snapshot.data}");
return CircularProgressIndicator();
},
);
}
readTablesFromDb()
{
if(readTable)
(readTables().then((value) => {
_tables.add(value)
}));
else _tables.add("No Tables");
}
}
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import 'dart:io';
import 'package:flutter/services.dart';
import 'package:path/path.dart';
import 'package:sqflite/sqflite.dart';
Database _database;
int _databaseVersion=1;
/// delete the db, create the folder and returnes its path
Future<String> readTables() async
{
Database db = await database;
var res=await db.rawQuery("select * FROM sqlite_master WHERE type ='table'");
if(res.length>0)
{
//mapData.entries.map( (entry) => Weight(entry.key, entry.value)).toList();
String s="";
for(int k=0;k<res.length;k++)
{
print("reading ");
for (var entry in res[k].entries) {
print(entry.key);
print(entry.value);
if(entry.key=="tbl_name")
s=s+ "Table Name: ${entry.value}\n";
else if(entry.key=="sql")
s=s+ "Table Query: ${entry.value}\n";
}
s=s+" \n\n ----------- \n\n";
}
return s;
}
return "No Tables found";
}
Future<String> readTables() async
{
Database db = await database;
var res=await db.rawQuery("select * FROM sqlite_master WHERE type ='table'");
if(res.length>0)
{
return res.first.entries.toString();
}
return "No Tables found";
}
Future get database async {
if (_database != null) return _database;
// lazily instantiate the db the first time it is accessed
_database = await _initDatabase();
return _database;
}
_initDatabase() async {
var databasesPath = await getDatabasesPath();
var path = join(databasesPath, "demo_asset_example.db");
return await openDatabase(path,
version: _databaseVersion,
onCreate: _onCreate);
}
// SQL code to create the database table
Future _onCreate(Database db, int version) async {
}
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