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 think that us web developers have to stop fighting with the complex IndexedDB API, stumbling on simple tasks, and waiting for LevelDB in the browser. Current specification is stable, available in modern browsers. And the upcoming 2.0 spec will not have breaking changes. IndexedDB is powerful technology with support of indexes, stores, transactions and cursors. It allows you 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. 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 you focus on real problems, building awesome libraries, and making the web better.

Main features

• Simple API around powerful IndexedDB features, like batch or indexes.
• Command buffering, you can start read/write right away.
• Small codebase without dependencies, ~400 LOC, 2.5Kb gziped.
• Powerful DSL to manage database schema and versions.
• Better error handling through error first node-style callbacks.
• Exposed access to low-level IndexedDB methods for 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 folder.

Installation

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

Standalone build available as treo.js.

<script src="treo.js"></script>
<script src="indexedb-shim.js"></script> <!-- for legacy browsers -->
<script>window.treo('my-db', schema);</script>

API

To initialize a new db instance, create a schema and pass it to main function. All methods, except multiple indexes and advanced ranges, are backward compatible with outdated browsers through IndexedDBShim.

// 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].

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.

DB

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

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

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.

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.

Ranges

treo.range(object) transforms javascript object to IDBKeyRange. Values inspired by MongoDB query operators:

• gt - greater than
• gte - greater or equal
• lt - less than
• lte - less or equal

Promises

Using then/promise:

var Promise = require('promise');
var books = db.store('books');
books.get = Promise.denodeify(books.get); // patch get method

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

Low Level Methods

Treo is designed to be a foundation for your browser storage. It gives you full power of IndexedDB through set of internal low level methods.

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.Schema, treo.Store, treo.Index

Exposed core objects.

treo.cmp(a, b)

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

License

Aleksey Kulikov, MIT.