clients/server/postgres.js

PostgreSQL

All of the "when.js" promise components needed in this module.

var when = require('when'); var nodefn = require('when/node/function');

Other dependencies, including the pg library, which needs to be added as a dependency to the project using this database.

var _ = require('underscore'); var pg = require('pg');

All other local project modules needed in this scope.

var ServerBase = require('./base').ServerBase; var Helpers = require('../../lib/helpers').Helpers; var grammar = require('./postgres/grammar').grammar; var schemaGrammar = require('./postgres/schemagrammar').schemaGrammar;

Constructor for the PostgreSQL Client

exports.Client = ServerBase.extend({ dialect: 'postgresql',

Attach the appropriate grammar definitions onto the current client.

attachGrammars: function() { this.grammar = grammar; this.schemaGrammar = schemaGrammar; },

Runs the query on the specified connection, providing the bindings and any other necessary prep work.

runQuery: function(connection, sql, bindings, builder) { if (!connection) throw new Error('No database connection exists for the query'); var questionCount = 0; sql = sql.replace(/\?/g, function() { questionCount++; return '$' + questionCount; }); if (builder && builder.flags.options) sql = _.extend({text: sql}, builder.flags.options); return nodefn.call(connection.query.bind(connection), sql, bindings); },

Get a raw connection, called by the pool whenever a new connection needs to be added to the pool.

getRawConnection: function(callback) { var instance = this; var connection = new pg.Client(this.connectionSettings); return nodefn.call(connection.connect.bind(connection)).tap(function() { if (!instance.version) return instance.checkVersion(connection); }).yield(connection); },

Used to explicitly close a connection, called internally by the pool when a connection times out or the pool is shutdown.

destroyRawConnection: function(connection) { connection.end(); },

In PostgreSQL, we need to do a version check to do some feature checking on the database.

checkVersion: function(connection) { var instance = this; this.runQuery(connection, 'select version();').then(function(resp) { instance.version = /^PostgreSQL (.*?) /.exec(resp.rows[0].version)[1]; }); } });