Pegasus

An ActionScript 3 driver for the PostgreSQL open source database.

Overview

Pegasus currently supports both the simple and extended query protocols, clear-text, md5 hashed, and trust authentication, and the PostgreSQL notification mechanism (LISTEN/NOTIFY). It has an extensible data type handling system with built-in support for the most common types (Date, Number, int, Boolean, and String in ActionScript, and their PostgreSQL equivalents).

The pegasus core library can be used in plain Flash stand-alone applications, Flash web applications, and Flex or AIR applications (albeit the Flash cross-domain policies will prevent you from doing anything too colorful from a web app).

The pegasus repository includes pgconsole, a simple AIR application which can connect to a PostgreSQL server, issue queries, and display results. It also supports notifications (i.e., you can issue a LISTEN and get notifications of the corresponding NOTIFY events).

Example

Here is an example of pegasus usage:

// Create a ConnectionFactory
var connFactory:ConnectionFactory = new ConnectionFactory();

// Pegasus uses jdbc-like URLs for configuring host, port, and target database
// as well as for connection properties (not shown)
var url:String = 'asdbc:postgresql://localhost:5432/postgres';
var user:String = 'postgres';
var password:String = 'postgres';
var conn:IConnection = connFactory.createConnection(url, user, password);

// Add event listeners. The actual functions are omitted; they are fairly
// straightforward event handlers. Note that the NoticEvent.ERROR handler
// is the mechanism for communicating query errors, so be sure to listen
// for at least these events
conn.addEventListener(NoticeEvent.NOTICE, handleNotice);
conn.addEventListener(NoticeEvent.ERROR, handleError);
conn.addEventListener(ParameterChangeEvent.PARAMETER_CHANGE, handleParamChange);
conn.addEventListener(NotificationEvent.NOTIFICATION, handleNotification);
conn.addEventListener(ConnectionEvent.CONNECTED, handleConnected);
conn.addEventListener(ConnectionErrorEvent.CONNECTIVITY_ERROR, handleConnectivityError);
conn.addEventListener(ConnectionErrorEvent.PROTOCOL_ERROR, handleProtocolError);
conn.addEventListener(ConnectionErrorEvent.CODEC_ERROR, handleCodecError);

// Each query needs a result handler. Pegasus comes with two types of result handlers,
// or you can write your own. A result handler needs to respond to results from
// the query (if any) and to successful query completion. The EventResultHandler dispatches
// events when results are available and when the query completes.
var handler:IResultHandler = new EventResultHandler();
// Add a handler for query results; you can often ignore completion
IEventDispatcher(handler).addEventListener(QueryResultEvent.RESULT, handleResult);
// Parameter markers use standard PostgreSQL syntax. Parameter input
// mappings (from ActionScript data types to PostgreSQL types) are
// configurable, but defaults are sensible for simple use cases.
conn.execute(handler, "select 'hello ' || $1", [ 'world' ]);

This is a sample result handler:

function handleResult(event:QueryResultEvent):void {
    trace("Columns are:");
    for (var col:IColumn in event.columns) {
        trace('Column', col.name, col.type);
    }
    trace("Data is:");
    // PostgreSQL data types are automatically mapped to corresponding
    // ActionScript data types (the mappings can be reconfigured, but
    // again, the defaults are sensible for simple uses)
    for (var row:Object in event.data) {
        for (var col:IColumn in event.columns) {
            trace("Value for column", col.name, "is", row[col.name]);
        }
    }
}

A more extensive example is available in pgconsole. Asdoc API documentation is also available.