sqlcool 4.1.0

Easy and reactive Sqlite. Stream of changes, select bloc, custom database models

Sqlcool

A database helper library for Sqflite. Forget about implementation details and focus on the business logic.

• Simple: easy api for crud operations
• Reactive: stream of changes, select bloc
• Adaptative: plug custom models into the database

Check the documentation or the api doc for usage instructions

Simple crud

Define the database schema

import 'package:sqlcool/sqlcool.dart';

Db db = Db();
// define the database schema
DbTable category = DbTable("category")..varchar("name", unique: true);
DbTable product = DbTable("product")
   ..varchar("name", unique: true)
   ..integer("price")
   ..text("descripton", nullable: true)
   ..foreignKey("category", onDelete: OnDelete.cascade)
   ..index("name");
List<DbTable> schema = [category, product];

Initialize the database

String dbpath = "db.sqlite"; // relative to the documents directory
await db.init(path: dbpath, schema: schema).catchError((e) {
  throw("Error initializing the database: ${e.message}");
});

Insert

Map<String, String> row = {name: "My item",};
await db.insert(table: "category", row: row).catchError((e) {
  throw("Error inserting data: ${e.message}");
});

Select

List<Map<String, dynamic>> rows = await db.select(
   table: "product", limit: 20, columns: "id,name",
   where: "name LIKE '%something%'",
   orderBy: "name ASC").catchError((e) {
    throw("Error selecting data: ${e.message}");
});

Update

int updated = await db.update(table: "category", 
   row: row, where: "id=1").catchError((e) {
      throw("Error updating data: ${e.message}");
});

Delete

db.delete(table: "category", where: "id=3").catchError((e) {
   throw("Error deleting data: ${e.message}");
});

Reactivity

Changefeed

A stream of database change events is available. Inspired by Rethinkdb

import 'dart:async';
import 'package:sqlcool/sqlcool.dart';

StreamSubscription changefeed;

changefeed = db.changefeed.listen((change) {
   print("Change in the database:");
   print("Query: ${change.query}");
   if (change.type == DatabaseChange.update) {
     print("${change.value} items updated");
   }
 });
// Dispose the changefeed when finished using it
changefeed.cancel();

Reactive select bloc

The bloc will rebuild itself on any database change because of the reactive parameter set to true:

import 'package:flutter/material.dart';
import 'package:sqlcool/sqlcool.dart';

class _PageSelectBlocState extends State<PageSelectBloc> {
  SelectBloc bloc;

  @override
  void initState() {
    super.initState();
    this.bloc = SelectBloc(
        table: "items", orderBy: "name", reactive: true);
  }

  @override
  void dispose() {
    bloc.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("My app")),
      body: StreamBuilder<List<Map>>(
          stream: bloc.items,
          builder: (BuildContext context, AsyncSnapshot snapshot) {
            if (snapshot.hasData) {
              // the select query has not found anything
              if (snapshot.data.length == 0) {
                return Center(child: const Text("No data"));
              }
              // the select query has results
              return ListView.builder(
                  itemCount: snapshot.data.length,
                  itemBuilder: (BuildContext context, int index) {
                    var item = snapshot.data[index];
                    return ListTile(
                      title: GestureDetector(
                        child: Text(item["name"]),
                        onTap: () => someFunction()),
                    );
                  });
            } else {
              // the select query is still running
              return CircularProgressIndicator();
            }
          }),
    );
  }
}

class PageSelectBloc extends StatefulWidget {
  @override
  _PageSelectBlocState createState() => _PageSelectBlocState();
}

Database models

New in 4.0.0: define models that have database methods. The main advantage of this is to use only typed model data and avoid the type conversions from maps for every query. It directly plugs custom models into the database. Example:

In schema.dart:

final carTable = DbTable("car")
  ..varchar("name")
  ..integer("max_speed")
  ..real("price")
  ..integer("year")
  ..boolean("is_4wd", defaultValue: false)
  ..foreignKey("manufacturer", onDelete: OnDelete.cascade);

final manufacturerTable = DbTable("manufacturer")..varchar("name");

In car_model.dart:

import 'package:sqlcool/sqlcool.dart';
// the database schema
import 'schema.dart';
// another model
import 'manufacturer_model.dart';

class Car with DbModel {
  Car(
      {this.id,
      this.name,
      this.maxSpeed,
      this.price,
      this.year,
      this.is4wd,
      this.manufacturer});

  /// define some class properties

  final String name;
  final int maxSpeed;
  final double price;
  final DateTime year;
  final bool is4wd;
  // this is a foreign key to another model
  Manufacturer manufacturer;

  /// [DbModel] required overrides

  @override
  int id;

  /// the [Db] used
  /// pass it your main db
  @override
  Db get db => db;

  /// the table schema representation
  /// check example/pages/dbmodels/schema.dart
  @override
  DbTable get table => carTable;

  /// serialize a row to the database
  @override
  Map<String, dynamic> toDb() {
    // we want the foreign key to be recorded
    assert(manufacturer?.id != null);
    final row = <String, dynamic>{
      "name": name,
      "max_speed": maxSpeed,
      "price": price,
      "year": year.millisecondsSinceEpoch,
      "is_4wd": is4wd,
      "manufacturer": manufacturer.id
    };
    return row;
  }

  /// deserialize a row from database
  @override
  Car fromDb(Map<String, dynamic> map) {
    final car = Car(
      id: map["id"] as int,
      name: map["name"].toString(),
      maxSpeed: map["max_speed"] as int,
      price: map["price"] as double,
      year: DateTime.fromMillisecondsSinceEpoch(map["year"] as int),
      is4wd: (map["is_4wd"].toString() == "true"),
    );
    // the key will be present only with join queries
    // in a simple select this data is not present
    if (map.containsKey("manufacturer")) {
      car.manufacturer =
          Manufacturer().fromDb(map["manufacturer"] as Map<String, dynamic>);
    }
    return car;
  }

  /// Create a static join method for convenience

  static Future<List<Car>> selectRelated({String where, int limit}) async {
    final cars = List<Car>.from(
        await Car().sqlJoin(where: where, limit: limit, verbose: true));
    return cars;
  }
}

Then use the models:

/// car is an instance of [Car]
await car.sqlInsert();
await car.sqlUpdate();
await car.sqlUpsert();
await car.sqlDelete();
final cars = Car.selectRelated(where: "speed>200");
// foreign keys are retrieved as model instances
print(cars[0].manufacturer.name);

Using this

• Sqlview: admin view and infinite list view
• Kvsql: a type safe key/value store
• Geopoint sql: sql operations for geospatial data