db.js

db.js is a wrapper for IndexedDB to make it easier to work against, making it look more like a queryable API.

Usage

Add a reference to db.js in your application before you want to use IndexedDB:

<script src='/scripts/db.js'></script>

Alternatively, db.js includes an optional define call, and can be loaded as module using the AMD loader of your choice.

Once you have the script included you can then open connections to each different database within your application:

var server;
db.open( {
    server: 'my-app',
    version: 1,
    schema: {
        people: {
            key: { keyPath: 'id' , autoIncrement: true },
            // Optionally add indexes
            indexes: {
                firstName: { },
                answer: { unique: true }
            }
        }
    }
} ).done( function ( s ) {
    server = s
} );

A connection is intended to be persisted and you can perform multiple operations while it's kept open. Check out the /tests/public/specs folder for more examples.

General

Note that the methods below can be called either as server.people.xxx( arg1, arg2, ... ) or server.xxx( 'people', arg1, arg2, ... ).

Adding items

server.people.add( {
    firstName: 'Aaron',
    lastName: 'Powell',
    answer: 42
} ).done( function ( item ) {
    // item stored
} );

Removing

server.people.remove( 1 ).done( function ( key ) {
    // item removed
} );

Clearing

This allows removing all items in a table/collection:

server.people.clear()
    .done(function() {
        // all table data is gone.
    })

Fetching

Getting a single object by ID

server.people.query( 'firstName' , 'Aaron' )
      .execute()
      .done( function ( results ) {
          // do something with the results
      } );

Querying all objects, with optional filtering

server.people.query()
      .filter( 'firstName', 'Aaron' )
      .execute()
      .done( function ( results ) {
          // do something with the results
      } );

Querying using indexes

All ranges supported by IDBKeyRange can be used.

server.people.query( 'indexName' )
      .only( 'firstName', 'Aaron' )
      .done( function ( results ) {
          //do something with the results
      } );

server.people.query( 'indexName' )
      .bound( 'answer', 30, 50 )
      .done( function ( results ) {
          //do something with the results
      } );

Atomic updates

Any query that returns a range of results can also be set to modify the returned records atomically. This is done by adding .modify() at the end of the query (right before .execute()).

modify only runs updates on objects matched by the query, and still returns the same results to the done() function (however, the results will have the modifications applied to them).

Examples:

// grab all users modified in the last 10 seconds,
server.users.query('last_mod')
    .lowerBound(new Date().getTime() - 10000)
    .modify({last_mod: new Date.getTime()})
    .execute()
    .done(function(results) {
        // now we have a list of recently modified users
    });

// grab all changed records and atomically set them as unchanged
server.users.query('changed')
    .only(true)
    .modify({changed: false})
    .execute()
    .done(...)

// use a function to update the results. the function is passed the original
// (unmodified) record, which allows us to update the data based on the record
// itself.
server.profiles.query('name')
    .lowerBound('marcy')
    .modify({views: function(profile) { return profile.views + 1; }})
    .execute()
    .done(...)

modify can be used after: all, filter, desc, distinct, only, bound, upperBound, or lowerBound.

Closing connection

server.close();

Deferred/ Promise notes

db.js used the Promise spec to handle asynchronous operations. All operations that are asynchronous will return an instance of the internal Promise object that exposes a then method which will take up to three callbacks, success, failed and progress. It also exposes useful helpers for these such as done, fail and progress.

As of version 0.7.0 db.js's Promise API is designed to work with jQuery*, allowing you to link db.js Promises with other Promises.

*Note: It's likely that other Promise libraries also integrate with it, jQuery is just the only tested on.

The MIT License

Copyright (c) 2012 Aaron Powell