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='/dist/db.js'></script>

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

Opening/Creating a database and connection

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}
            }
        }
    }
}).then(function (s) {
    server = s;
});

Note that open() takes an options object with the following properties:

• version - The current version of the database to open. Should be an integer. You can start with 1. You must increase the version if updating the schema or otherwise the schema property will have no effect.

• server - The name of this server. Any subsequent attempt to open a server with this name (and with the current version) will reuse the already opened connection (unless it has been closed).

• schema - Expects an object, or, if a function is supplied, a schema object should be returned). A schema object optionally has store names as keys (these stores will be auto-created if not yet added). The values of these schema objects should be objects, optionally with the property "key" and/or "indexes". The "key" property, if present, should contain valid createObjectStore parameters (keyPath or autoIncrement). The "indexes" property should contain an object whose keys are the desired index keys and whose values are objects which can include the optional parameters and values available to createIndex (unique, multiEntry, and, for Firefox-only, locale). Note that the keyPath of the index will be set to the supplied index key, or if present, a key property on the provided parameter object. Note also that when a schema is supplied for a new version, any object stores not present on the schema object will be deleted.

A connection is intended to be persisted, and you can perform multiple operations while it's kept open.

In the event a connection has already been opened for modification (whether in the same instance or in another tab/window), a blocking error will occur, for which you can listen by adding a Promise.catch statement and communicate with blocking instances still holding a connection so that they may close the connection. You can then return the resume property (a promise) to recover to continue the original open operation and proceed to the following then condition.

var server;
db.open({
    // ...
}).catch(function (err) {
    if (err.type === 'blocked') {
        oldConnection.close();
        return err.resume;
    }
    // Handle other errors here
    throw err;
}).then(function (s) {
    server = s;
});

For cases where the blocking connections are in other tabs/windows, window.postMessage might be a suitable way to communicate with them to get them to close their connections or whatever behavior is desired.

Check out the /tests/specs folder for more examples.

General server/store methods

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

To reduce some memory requirements or avoid a however unlikely potential conflict with server method names, however, one may supply noServerMethods: true as part of options supplied to db.open() and under such conditions, only the second method signature above can be used.

Store modification

Adding items

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

Updating

server.people.update({
    firstName: 'Aaron',
    lastName: 'Powell',
    answer: 42
}).then(function (item) {
    // item added or updated
});

Removing

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

Clearing

This allows removing all items in a table/collection:

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

Fetching

Getting a single object by key

server.people.get(5)
    .then(function (results) {
        // do something with the results
    });

Getting a single object by key range

If more than one match, it will retrieve the first.

With a MongoDB-style range:

server.people.get({gte: 1, lt: 3})
    .then(function (results) {
        // do something with the results
    });

With an IDBKeyRange:

server.people.get(IDBKeyRange.bound(1, 3, false, true))
    .then(function (results) {
        // do something with the results
    });

Querying

Queries require one or more methods to determine the type of querying (all items, filtering, applying ranges, limits, distinct values, or custom mapping--some of which can be combined with some of the others), any methods for cursor direction, and then a subsequent call to execute() (followed by a then or catch).

Querying all objects

server.people.query()
    .all()
    .execute()
    .then(function (results) {
        // do something with the results
    });

Querying using indexes

server.people.query('specialProperty')
    .all()
    .execute()
    .then(function (results) {
        // do something with the results (items which possess `specialProperty`)
    });

Querying with filtering

Filter with property and value

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

Filter with function

server.people.query()
    .filter(function(person) {return person.group === 'hipster';})
    .execute()
    .then(function (results) {
        // do something with the results
    });

Querying with ranges

All ranges supported by IDBKeyRange can be used (only, bound, lowerBound, upperBound).

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

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

MongoDB-style ranges (as implemented in idb-range-driven libraries) are also supported:

server.people.query('firstName')
    .range({eq: 'Aaron'})
    .then(function (results) {
        // do something with the results
    });

server.people.query('answer')
    .range({gte: 30, lte: 50})
    .then(function (results) {
        // do something with the results
    });

Querying for distinct values

Will return only one record:

server.people
    .query('firstName')
    .only('Aaron')
    .distinct()
    .execute()
    .then(function (data) {
        //
    });

Limiting cursor range

Unlike key ranges which filter by the range of present values, one may define a cursor range to determine whether to skip through a certain number of initial result items and to select how many items (up to the amount available) should be retrieved from that point in the navigation of the cursor.

server.people
    .query('firstName')
    .all()
    .limit(1, 3)
    .execute()
    .then(function (data) {
        // Skips the first item and obtains the next 3 items (or less if there are fewer)
    });

Cursor direction (desc)

The desc method may be used to change cursor direction to descending order:

server.people.query()
    .all()
    .desc()
    .execute()
    .then(function (results) {
        // Array of results will be in descending order
    });

Retrieving special types of values

Keys

Keys may be retrieved with or without an index:

server.people.query('firstName')
    .only('Aaron')
    .keys()
    .execute()
    .then(function (results) {
        // `results` will contain one 'Aaron' value for each
        //    item in the people store with that first name
    });

Mapping

The map method allows you to modify the object being returned without correspondingly modifying the actual object stored:

server.people
    .query('age')
    .lowerBound(30)
    .map(function (value) {
        return {
            fullName: value.firstName + ' ' + value.lastName,
            raw: value
        };
    })
    .execute()
    .then(function (data) {
        // An array of people objects containing `fullName` and `raw` properties
    });

Counting

To count while utilizing an index and/or the query-returned methods, you can use the following:

server.people.query('firstName')
    .only('Aaron')
    .count()
    .execute()
    .then(function (results) {
        // `results` will equal the total count of "Aaron"'s
    });

If you only need a count of items in a store with only a key or range, you can utilize server.count:

// With no arguments (count all items)
server.people.count().then(function (ct) {
    // Do something with "ct"
});

// With a key
server.people.count(myKey).then(function (ct) {
    // Do something with "ct"
});

// With a MongoDB-style range
server.people.count({gte: 1, lt: 3}).then(function (ct) {
    // Do something with "ct"
});

// With an IDBKeyRange range
server.people.count(IDBKeyRange.bound(1, 3, false, true)).then(function (ct) {
    // Do something with "ct"
});

Atomic updates

Any query that returns a range of results can also be set to modify the returned records automatically. 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()
    .then(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()
    .then(...)

// 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()
    .then(...)

modify changes will be seen by any map functions.

modify can be used after: all, filter, ranges (range, only, bound, upperBound, and lowerBound), desc, distinct, and map.

Other server methods

Closing connection

server.close();

Retrieving the indexedDB.open result object in use

var db = server.getIndexedDB();
var storeNames = db.objectStoreNames;

Deleting a database

db.delete(dbName).then(function (ev) {
    // Should have been a successful database deletion
}, function (err) {
    // Error during database deletion
});

As with the open operation, a delete operation will not be able to execute so long as there are already opened blocking connections (i.e., those allowing for database modification) which are open elsewhere in the browser. You can recover as follows:

db.delete(dbName).catch(function (err) {
    if (err.type === 'blocked') {
        oldConnection.close();
        return err.resume;
    }
    // Handle other errors here
    throw err;
}).then(function (ev) {
    // Should have been a successful database deletion
});

See the documentation on open for more on such recovery from blocking connections.

Comparing two keys

Returns 1 if the first key is greater than the second, -1 if the first is less than the second, and 0 if the first is equal to the second.

db.cmp(key1, key2);

Promise notes

db.js used the es6 Promise spec to handle asynchronous operations.

All operations that are asynchronous will return an instance of the es6 Promise object that exposes a then method which will take up to two callbacks, onFulfilled and onRejected. Please refer to es6 promise spec for more information.

As of version 0.7.0 db.js's Promise API is designed to work with es6 Promises, please polyfill it if you would like to use other promise library.

Contributor notes

• npm install to install all the dependencies
• npm run grunt test:local to run the mocha server
• Open (http://localhost:9999/tests)[] to run the mocha tests

License

The MIT License

Copyright (c) 2012-2015 Aaron Powell, Brett Zamir