Integration

This document is the guidelines for integrating pg-promise with reusable libraries.

standard approach

The standard way is by adding pg-promise as a dependency in your package.json.

advantages:

• isolated use of promise libraries
• coding strictly for the referenced version of pg-promise
• providing your own Initialization Options

disadvantages:

• requires separate database connection parameters
• requires creation of a separate instance of the Database object

If the client module creates its own Database object from the same connection parameters, it will result in a duplicate Database object warning, as explained in the Database API.

via db parameter

You can accept db - Database object as a parameter, to use it directly. And you can access all pg-promise features via property db.$config.

advantages:

• consistent use of the Initialization Options, as configured by the client
• no dependencies: reusing pg-promise and the promise library as configured by the client
• no duplicate Database objects, optimal use of the connection and event listeners

disadvantages:

• cannot set your own Initialization Options, and you can break the client's code, if you try
• can only use the basic promise methods as exposed via db.$config.promise

mixed approach

You can support pg-promise through explicit dependencies (for the default), and via db parameter as a optional override.

This is the recommended approach, because it can suit the needs of both client types:

• clients that use pg-promise internally will be able to pass in db as a parameter
• clients that do not use pg-promise internally will rely on your library's defaults

extras

When using pg-promise via db parameter, you have access to the underlying layer of promises:

• db.$config.promiseLib - the promise library that's being used
• db.$config.promise - the simplified promise interface as used by pg-promise

If you want to provide compatibility with any promise library configured by pg-promise client, you have to rely on the simplified promise interface.

Example:

var $p = db.$config.promise; // your promise interface

// creating and returning a new promise object:
return $p(function(resolve, reject) {
   // call resolve/reject as required
});

// returning a resolved promise:
return $p.resolve(value);

// returning a rejected promise:
return $p.reject(reason);

There are no other methods in that promise interface beside the ones shown above.