evant/streamqflite

flutter reactive stream wrapper around sqflite inspired by sqlbrite

streamqflite

A reactive stream wrapper around sqflite inspired by sqlbrite.

Getting Started

In your flutter project, add the dependency to your pubspec.yaml

dependencies:
  ...
  streamqflite: ^1.0.0

Usage

Import streamqflite.dart

import 'package:streamqflite/streamqflite.dart';

Wrap your database in a StreamDatabase.

var streamDb = StreamDatabase(db);

You can then listen to a query

// Emits a single row, doesn't emit if the row dosen't exist.
Stream<MyEntry> singleQuery = streamDb.createQuery("MyTable", where: 'id = ?', whereArgs: [id])
    .mapToOne((row) => MyEntry(row));

// Emits a single row, or the given default value if the row doesn't exist.
Stream<MyEntry> singleOrDefaultQuery = streamDb.createQuery("MyTable", where: 'id = ?', whereArgs: [id])
    .mapToOneOrDefault((row) => MyEntry(row), MyEntry.empty());

// Emits a list of rows.
Stream<List<MyEntry>> listQuery = streamDb.createQuery("MyTable", where: 'name LIKE ?', whereArgs: [query])
    .mapToList((row) => MyEntry(row));

var flexibleQuery = streamDb.createQuery("MyTable", where: 'name LIKE ?', whereArgs: [query])
    .asyncMap((query) => {
        // query is lazy, this lets you not even execute it if you don't need to.
        if (condition) {
            return query();
        } else {
            return Stream.empty();
        }
    }).map((rows) {
        // Do something with all the rows.
        return ...;
    });

These queries will run once to get the current data, then again whenever the given table is modified though the StreamDatabase.

streamqflite's Issues

Testing - How can I mock it?

First at all, thx for the amazing lib...
I would like to know how can I stub to test my functions, I'm trying to mock it but I don't know how to do it
First I wanna to test this call

  Stream<List<Customer>> fetchCustomers() => db.createQuery('customers')
    .mapToList(_mapCustomer);

I'm trying this:

      test("it returns a list with fake customer", () async {
        when(mockDatabase.createQuery('customers')
          .mapToList((row) => Customer.fromDB(row)))
          .thenAnswer((_) => Stream.fromIterable([fakeCustomer].cast()));

        Stream<List<Customer>> subject = CustomersCache(mockDatabase)
          .fetchCustomers();

        expect(subject, emits([fakeCustomer]));
      });

I think that I need to mock createQuery but how can I do?

Provide generic map function

Is there a generic map function I can use with this library?

My app uses BuiltList instead of List so I want to do something like this

  Stream<BuiltList<T>> mapToBuiltList<T>(T mapper(Map<String, dynamic> row)) {
    return _source.asyncMap((query) => query()).map((rows) {
      var result = BuiltList<T>().toBuilder();

      for (final row in rows) {
        result.add(mapper(row));
      }

      return result.build();
    });
  }

I think the library should expose a generic map function so that any data structure can be used.

_source.asyncMap((query) => query()) is the part that could be exposed.

Update to sqflite v1.1.1

Update required to sqflite 1.1.1 to remove dependency on deprecated Android support library.

sqflite: ^2.2.3

For some reason I cant push a pull request, but here is the update of the project with Dart 3 incompatible fixed and null safety:

https://github.com/silexcorp/streamqflite

Update dependency on sqflite

Can you please update the dependency to sqflite: ^1.0.0

Still interested in maintaining this project?

Hey,

I just wanted to know whether you're still interested in maintaining this project.

I had the same idea for a library like this this weekend but saw that yours is existing. The only thing missing is Dart 2 support.

If you're still interested, I would try to submit a PR where all libraries are updated and Dart 2 is supported.

Performance question

Hi @evant

Thank you for making this library.

Just wondering when I make a query then subscribe to the stream, then I cancel the subscription is the query then no longer observed for changes.

Just wanted to make sure that my SQL queries aren't accumulating and then all being watched for changes even when there are no subscribers.