A unified, asynchronous, easy-to-use library for offline-enabled browser-based web apps. Kinda sorta a port of Lawnchair to Dart, but with Futures and Streams.
Lawndart uses Futures to provide an asynchronous, yet consistent, interface to local storage, indexed db, and websql. This library is designed for simple key-value usage, and is not designed for complex transactional queries. This library prefers simplicity and uniformity over expressiveness.
You can use this library to help deal with the wide array of client-side storage options. You should be able to write your code against the Lawndart interface and have it work across browsers that support at least one of the following: local storage, indexed db, and websql.
// Picks the best store available. var db = new Store("simple-run-through", 'test'); db.open() .then((_) => db.nuke()) .then((_) => db.save("world", "hello")) .then((_) => db.save("is fun", "dart")) .then((_) => db.getByKey("hello")) .then((value) => querySelector('#text').text = value);
See the example/ directory for more sample code.
Choosing the best storage option
This is now made easy for you. Simply create a new instance of Store:
var store = new Store('dbName', 'storeName');
The factory constructor will try IndexedDB, then WebSQL, and then finally local storage. Of course, you can perform your own logic to choose which option works for you.
Opens the database and makes it available for reading and writing.
Wipes the database clean. All records are deleted.
Future save(value, key)
Stores a value accessible by a key.
Retrieves a value, given a key.
Returns all keys.
Returns all values.
Stores all values and their keys.
Returns all values, given keys.
Returns true if the key exists, or false.
Removes the value for the key.
Removes all values for the keys.
Most methods return a Future, like
Methods that would return many things, like
all, return a Stream.
You must call
open() before you can use the database.
Supported storage mechanisms
- Indexed DB - Great choice for modern browsers
- WebSQL - Well supported in mobile WebKit browsers, not in Firefox
- Local Storage - Only 5MB, slow, more-or-less universal
- Memory - Good for testing
You can consult Can I Use? for a breakdown of browser support for the various storage technologies.
Lawndart is a pub package. To install it, and link it into your app, add lawndart to your pubspec.yaml. For example:
name: your_cool_app dependencies: lawndart: any
If you use Dart Editor, select your project from the Files view, then go to Tools, and run Pub Install.
If you use the command line, ensure the Dart SDK is on your path, and
Lawndart is hosted at https://github.com/sethladd/lawndart
You can file issues at https://github.com/sethladd/lawndart/issues
API docs at http://sethladd.github.com/lawndart/
This library is open source, pull requests welcome!
- Seth Ladd (email@example.com)
- Handle non-String keys and values appropriately.
- Wire into drone.io.
Copyright 2013 Google Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.