architect-pg-pool

Expose a posgresql connection pool as architect plugin. Automaticaly returns connection to the pool after query.

Installation

npm install --save architect-pg-pool

Config Format

module.exports = [{
    packagePath: "architect-pg-pool",
    url: 'postgresql://postgresuser:postgrespwd@localhost:5435/dbname',
    checkOnStartUp : true
}];

• url : Defines the postgres url to use for connection
• checkOnStartUp : Defines if we must check connection validity on startup default is false.

Usage

Boot Architect :

var path = require('path');
var architect = require("architect");
var configPath = path.join(__dirname, "config.js");
var config = architect.loadConfig(configPath);
architect.createApp(config, function (err, app) {
    if (err) {
        throw err;
    }
    console.log("app ready");
});

Configure Architect with config.js :

module.exports = [{
    packagePath: "architect-pg-pool",
    url: 'postgresql://postgresuser:postgrespwd@localhost:5435/dbname'
}, './routes'];

Consume db plugin in your ./routes/package.json :

{
  "name": "routes",
  "version": "0.0.1",
  "main": "index.js",
  "private": true,
  "plugin": {
    "consumes": ["db"]
  }
}

Eventually use pg connection in your routes ./routes/index.js :

module.exports = function setup(options, imports, register) {
    var rest = imports.rest;
    var db = imports.db;
    // register routes 
    rest.get('/hello/:name', function (req, res, next) {
        db.query('SELECT * FROM Users WHERE id=$1', [req.params.name], function(err, res){
            res.write("{'message':'hello," + res.rows[0].name + "'}");
            res.end();
        });
    });
    register();
};

Multiple pool configuration

This module supports multiple pools.

Here is how to define 2 different pools :

module.exports = [{
    packagePath: "architect-pg-pool",
    first : {
        url: 'postgresql://postgresuser:postgrespwd@localhost:5435/dbname'
    },
    second : {
        url: 'postgresql://postgresuser:postgrespwd@localhost:5432/otherdb'
    },
    checkOnStartUp : true
}];

This will create 2 properties (first and second) in the db object.

module.exports = function setup(options, imports, register) {
    var db = imports.db;
    db.first.connection(function (err, client) {
      client.query(/*...*/);
    });    
    register();
};

default pool

A pool can be marked as default and will be available in db.connection.
Here is how to define 2 different pools with the second as default :

module.exports = [{
    packagePath: "architect-pg-pool",
    first : {
        url: 'postgresql://postgresuser:postgrespwd@localhost:5435/dbname'
    },
    second : {
        url: 'postgresql://postgresuser:postgrespwd@localhost:5432/otherdb',
        'default' : true
    },
    checkOnStartUp : true
}];

This will create 2 properties (first and second) in the db object.

module.exports = function setup(options, imports, register) {
    var db = imports.db;
    // this will use second pool
    db.connection(function (err, client) {
      client.query(/*...*/);
    });
    // second pool is also available
    db.second.connection(function (err, client) {
      client.query(/*...*/);
    });
    register();
};

Configuration

• url either a connection url or an object :

  • host : serveur hostname or ip
  • port : serveur port
  • user : username to login,
  • password : password to login,
  • database: database name,
  • application_name: a name to identify client,
  • validationQuery: a query to run to validate a connection

• checkOnStartup : boolean, Whether we should try to validate configuration at startup.

API

The pool object (db) has the following methods :

connection

Retreive a connection from the pool. The method takes a callback as parameter. Once the connection is avaliable the callback is called with an :

• err object if an error occured or null;
• client the pg client object;
• done, the close method.

query

The query method let you directly query the database without worrying about the database connection. Behind the scene the method retreive a connection from the pool and close it afterward. The method signature is similar to node-pg query.

• string text: the query text;
• optional array parameters: the query parameters;
• optional function callback : the function called when data is ready.

Once the data is ready the callback is fired with an :

• err object if an error occured or null;
• rows the pg result set.

module.exports = function setup(options, imports, register) {
    var db = imports.db;
    db.query('SELECT * from USERS', function (err, res) {
        res.rows.forEach(console.log);
    });
    //...
};

queryStream

The queryStream method let you directly query the database without worrying about the database connection. This method passes a stream to the callback instead of a resultset. Behind the scene the method retreive a connection from the pool and close it afterward. The method signature is similar to node-pg query-stream.

• string text: the query text;
• optional array parameters: the query parameters;
• optional function callback : the function called when stream is ready.
• returns: ReadableStream

Once the stream is ready the callback is fired with an :

• err object if an error occured or null;
• stream the pg result stream.

var JSONSteam = require('JSONStream');
module.exports = function setup(options, imports, register) {
    var db = imports.db;
    db.queryStream('SELECT * from USERS')
        .pipe(JSONSteam.stringify())
        .pipe(process.stdout);
    //...
};