Flutter's sqflite queries - flutter

Question

I am working with an already existing database dictionary.db that has a table words and has 4 columns id, englishWord, germanWord, isFavorite.
Using Sqflite I am trying to return a list of German words based on an input in English pretty much the userflow works like this: user input an English word (example: "Ability") and I return a list of synonyms to that word in German.
My problem is I don't know how to do it the method I am trying returns the full list instead of only the intended search results
This is my Entity:
class Word {
final String id;
final String eng;
final String ger;
final String isFav;
Word({this.id, this.eng, this.ger, this.isFav});
Map<String, dynamic> toMap() {
return {
'wordId': id,
'englishWord': eng,
'germanWord': ger,
'isFavorite': isFav,
};
}
factory Word.fromMap(Map<String, dynamic> json) => new Word(
id: json['wordId'],
eng: json['englishWord'],
ger: json['germanWord'],
isFav: json['isFavorite']
);
}
And this is my database helper class:
class DatabaseHelper{
DatabaseHelper._();
static final DatabaseHelper databaseHelper = DatabaseHelper._();
Database _database;
static const String DB_NAME = "dict.db";
static const String TABLE = "words";
static const String ID = "wordId";
static const String ENGLISH_WORD = "englishWord";
static const String GERMAN_WORD = "germanWord";
static const String IS_FAV = "isFavorite";
Future<Database> get database async {
if (_database != null) return _database;
_database = await getDatabaseInstance();
return _database;
}
Future<Database> getDatabaseInstance() async {
io.Directory directory = await getApplicationDocumentsDirectory();
String path = join(directory.path, DB_NAME);
return await openDatabase(path, version: 1,
onCreate: (Database db, int version) async {
await db.execute("CREATE TABLE IF NOT EXISTS $TABLE ("
"$ID TEXT,"
"$ENGLISH_WORD TEXT,"
"$GERMAN_WORD TEXT,"
"$IS_FAV TEXT"
")");
});
}
//This is where I get the search result list
//I am stuck here I don't know where to go from here, I only get the full list
Future<List<Word>> searchEnglishResults(String userSearch) async{
final db = await database;
var response = await db.query("Word");
List<Word> list = response.map((c) => Word.fromMap(c)).toList();
return list;
}

Answer 1

I assumed the database is like below:
|id | englidhWord | germanWord | isFavorite |
|-------|-------------|-------------------|------------|
| 'id0' | 'bye' | 'Tschüss' | 'false' |
| 'id1' | 'bye' | 'Auf Wiedersehen' | 'true' |
so if the user searches for "bye", she/he should receive [ 'Tschüss', 'Auf Wiedersehen'](the Word model not only the German words).
For that, query has some options like where and whereArgs that you can use to search for a specific row on the database.
Here we want to search the database for rows that their englidhWord field has a value of bye.
Here is the edited version of your DB:
import 'dart:io';
import 'package:path/path.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sudoku/src/word.dart';
class DatabaseHelper {
DatabaseHelper._();
static final DatabaseHelper databaseHelper = DatabaseHelper._();
Database _database;
String DB_NAME = "dict.db";
static const String TABLE = "words";
static const String ID = "wordId";
static const String ENGLISH_WORD = "englishWord";
static const String GERMAN_WORD = "germanWord";
static const String IS_FAV = "isFavorite";
Future<Database> get database async {
if (_database != null) return _database;
_database = await getDatabaseInstance();
return _database;
}
Future<Database> getDatabaseInstance() async {
Directory directory = await getApplicationDocumentsDirectory();
String path = join(directory.path, DB_NAME);
return await openDatabase(path, version: 1,
onCreate: (Database db, int version) async {
await db.execute("CREATE TABLE IF NOT EXISTS $TABLE ("
"$ID TEXT,"
"$ENGLISH_WORD TEXT,"
"$GERMAN_WORD TEXT,"
"$IS_FAV TEXT"
")");
});
}
//add new words
Future<int> add(Word word) async {
final db = await database;
var response = await db.insert(TABLE, word.toMap());
return response;
}
//This is where I get the search result list
//I am stuck here I don't know where to go from here, I only get the full list
Future<List<Word>> searchEnglishResults(String userSearch) async {
final db = await database;
var response = await db
.query(TABLE, where: '$ENGLISH_WORD = ?', whereArgs: [userSearch]);
List<Word> list = response.map((c) => Word.fromMap(c)).toList();
return list;
}
}
And I show the result with listview on a page named MyApp
import 'package:flutter/material.dart';
import 'package:sudoku/src/db.dart';
import 'package:sudoku/src/word.dart';
class MyApp extends StatefulWidget {
MyApp({Key key}) : super(key: key);
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
DatabaseHelper db;
#override
void initState() {
db = DatabaseHelper.databaseHelper;
add();
super.initState();
}
add() async {
// await db.add(Word(eng: 'hi', ger: 'Hallo', id: 'id2', isFav: 'true'));
// await db.add(Word(eng: 'bye', ger: 'Tschüss', id: 'id0', isFav: 'fasle'));
// await db.add(
// Word(eng: 'bye', ger: 'Auf Wiedersehen', id: 'id0', isFav: 'true'));
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
body: FutureBuilder<List<Word>>(
future: db.searchEnglishResults('bye'),
builder: (BuildContext context, AsyncSnapshot<List<Word>> snapshot) {
if (snapshot.hasData)
return ListView.builder(
itemBuilder: (BuildContext context, int index) {
return ListTile(
title: Text(snapshot.data[index].ger),
subtitle: Text(snapshot.data[index].eng),
trailing: Text(snapshot.data[index].isFav),
);
},
itemCount: snapshot.data.length,
);
return Center(
child: CircularProgressIndicator(),
);
},
),
);
}
}
I included a function named "add" in database and MyApp's initState to add new words to database.
If you refresh app for multiple time, it will add repetitive rows, the reason is that you should make one of the DB field unique, here can be id to do so you should create the table like below:
return await openDatabase(path, version: 1,
onCreate: (Database db, int version) async {
await db.execute("CREATE TABLE IF NOT EXISTS $TABLE ("
"$ID TEXT NOT NULL PRIMARY KEY,"
"$ENGLISH_WORD TEXT,"
"$GERMAN_WORD TEXT,"
"$IS_FAV TEXT"
")");
});
Also in add function in DB, you should choose what should be done when it faces to a repetitive row(Word here), there are some options, one can be to replace it, it should change like this:
//add new words
Future<int> add(Word word) async {
final db = await database;
var response = await db.insert(TABLE, word.toMap(), conflictAlgorithm: ConflictAlgorithm.replace);
return response;
}
I hope it was what You were looking for.