Treo

Treo is a lightweight wrapper around IndexedDB to make browser storage more enjoyable to use. Think about it as jQuery for IndexedDB. It does not add new abstractions, but simplifies the API and increases code reliability.

I spent a lot of time reading the official specification and understanding its nuances. With treo I want to save this time for other developers, and help to focus on real problems and making the web better, instead of fighting with the complex IndexedDB API and stumbling on simple tasks.

IndexedDB is powerful technology with support of indexes, stores, transactions and cursors. It allows us to build any kind of client databases. And let's be clear, it's the only real option to store data in browser, because localStorage is synchronous and WebSQL is deprecated.

Main features

• Simple API for powerful features like batch or indexes.
• Command buffering, you can start read/write right away.
• Small codebase without dependencies, ~370 LOC, 2.5Kb gziped.
• Powerful DSL to manage database schema and versions.
• Plugins for promises support and websql polyfill.
• Better error handling through error first node-style callbacks.
• Handle versionchage event automatically, to safely close and reopen database connection
• Exposed access to low-level IndexedDB methods to cover edge cases.
• Easy to extend and create plugins.

Example

Let's rewrite the official w3c example with treo:

var treo = require('treo'); // or window.treo

// define db schema
var schema = treo.schema()
  .version(1)
    .addStore('books', { key: 'isbn' })
    .addIndex('byTitle', 'title', { unique: true })
    .addIndex('byAuthor', 'author')
  .version(2)
    .getStore('books')
    .addIndex('byYear', 'year')
  .version(3)
    .addStore('magazines')
    .addIndex('byPublisher', 'publisher')
    .addIndex('byFrequency', 'frequency');

// open db
var db = treo('library', schema);
db.version; // 3

// put some data in one transaction
var books = db.store('books');
books.batch([
  { isbn: 123456, title: 'Quarry Memories', author: 'Fred', year: 2012 },
  { isbn: 234567, title: 'Water Buffaloes', author: 'Fred', year: 2012 },
  { isbn: 345678, title: 'Bedrock Nights', author: 'Barney', year: 2013 },
], function(err) {
  // Before this point, all actions were synchronous, and you don't need to wait
  // for db.open, initialize onupgradeneeded event, create readwrite transaction,
  // and handle all possible errors, blocks, aborts.
  // If any error happen on one of this steps, you get it as `err`.
});

// get a single book by title using an index
books.index('byTitle').get('Bedrock Nights', function(err, book) {});

// get all books filtered by author
books.index('byAuthor').get('Fred', function(err, all) {}); // all.length == 2

For more examples check out /examples:

• simple key value storage
• use ES6 generators and promises for nice async workflow
• plugin example

Installation

$ npm install treo --save
$ bower install treo
$ component install treojs/treo

Standalone build available as dist/treo.js.

<script src="treo.js"></script>
<script src="treo-websql.js"></script> <!-- [optional] for legacy browsers -->
<script src="treo-promise.js"></script> <!-- [optional] for es6-promises support -->
<script>
  var db = window.treo('my-db', schema)
    .use(treoWebsql())
    .use(treoPromise());
</script>

Promises

IndexedDB does not support ES6-Promises, but treo enables it with treo-promise plugin.

var promise = require('treo/plugins/treo-promise'); // or window.treoPromise
var db = treo('library', schema)
  .use(promise());

var books = db.store('books');

Promise.all([
  books.get('123456'),
  books.get('234567'),
  books.get('345678'),
]).then(function(records) {
  console.log(records); // records.length == 3

  books.count().then(function(count) {
    console.log(count); // total count of records
  });
});

Legacy browsers

IndexedDB is available only in modern browsers, but we still need to support Safari <= 7 and legacy mobile browsers. Treo ships with treo-websql plugin, which enables fallback to WebSQL and fix all issues of buggy IndexedDBShim. In fact all treo's tests pass even in phantomjs environment.

Usage:

var websql = require('treo/plugins/treo-websql'); // or window.treoWebsql
var db = treo('library', schema)
  .use(websql());

API

To initialize a new db instance, create a schema and pass it to main function.

// define schema with one storage
var schema = treo.schema()
  .version(1)
  .addStore('storage');

// create db
var db = treo('key-value-storage', schema);
db.store('storage')
  .put('foo', 'value 1', fn); // connect, create db, put value

Schema

Treo uses treo.schema() to setup internal objects like stores and indexes for right away access. Also, based on schema, treo generates onupgradeneeded callback.

schema.version(version)

Change current version.

schema.addStore(name, opts)

Declare store with name. Available options:

• key - setup keyPath for easy work with objects [default false]
• increment - generate incremental key automatically [default false]

schema.addIndex(name, field, opts)

Declare index with name to one specific field. It can be called after store declaration or use schema.getStore(name) to change current store. Available options:

• unique - index is unique [default false]
• multi - declare multi index for array type field [dafault false]

schema.getStore(name)

Change current store.

schema.dropStore(name)

Delete store by name.

schema.dropIndex(name)

Delete index by name from current store.

DB

It's an interface to manage db connections, create transactions and get access to stores, where real work happen.

db.use(fn)

Use plugin fn(db, treo), it calls with db instance and treo object, so you don't need to require treo as dependencies.

db.store(name)

Get store by name. See Store API for more information.

db.close([fn])

Close db connection. Callback is optional when db.status == 'open'.

db.drop(fn)

Close connection and drop database.

db.properties

• version - db version
• name - db name
• status - connection status: close, opening, open
• origin - original IDBDatabase instance

Store

Store is the primary storage mechanism for storing data. Think about it as table in SQL database.

store.get(key, fn)

Get value by key.

store.put(key, val, fn) or store.put(obj, fn)

Put val to key. Put means create or replace. If it's an object store with key property, you pass the whole object. fn callback returns error and key of new value.

var schema = treo.schema()
  .version(1)
  .addStore('books', { key: 'isbn' });

var db = treo('key-value-storage', schema);
db.get('books').put({ isbn: 123456, title: 'Quarry Memories', author: 'Fred' }, fn);
// key is isbn field and equal 123456

store.del(key, fn)

Delete value by key.

store.batch(opts, fn)

Create/update/remove objects in one transaction. opts can be an object or an array (when key option is specified).

var db = treo('key-value-storage', schema);
var storage = db.store('storage');

storage.put('key1', 'value 1', fn);
storage.put('key2', 'value 2', fn);

storage.batch({
  key1: 'update value',
  key2: null, // delete value
  key3: 'new value',
}, fn);

store.count(fn)

Count records in store.

store.all(fn)

Get all records.

store.clear(fn)

Clear store.

store.index(name)

Get index by name.

Index

Index is a way to filter your data.

index.get(key, fn)

Get values by key. When index is unique it returns only one value. key can be string, range, or IDBKeyRange object.

books.index('byTitle').get('Bedrock Nights', fn); // get unique value
books.index('byAuthor').get('Fred', fn); // get array of matching values
books.index('byYear').get({ gte: 2012 });
books.index('byAuthor', IDBKeyRange.only('Barney'));

index.count(key, fn)

Count records by key, similar to get, but returns number.

Low Level Methods

db.getInstance(cb)

Connect to db and create defined stores. It's useful, when you need to handle edge cases related with using origin database object.

db.transaction(type, stores, fn)

Create new transaction to list of stores. Available types: readonly and readwrite.

store.cursor(opts, fn), index.cursor(opts, fn)

Create custom cursors, see example and article for more detailed usage.

treo.Treo, treo.Store, treo.Index

Treo exposes core objects for plugins extension.

treo.cmp(a, b)

Compare 2 values using indexeddb's internal key compassion algorithm.

License

MIT