architect-pg-pool

architect-pg-pool 
=================

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

$3

``sh
npm install --save architect-pg-pool
`

$3


`js
module.exports = [{
packagePath: "architect-pg-pool",
pools: {
poolname: {
user: 'dbuser',
password: process.env.DB_PASSWORD,
host: 'db.example.com',
port: 5432,
database: 'dbname'
}
}
checkOnStartUp : true
}];
`
* pools : Defines the postgres pools to use
checkOnStartUp : Defines if we must check connection validity on startup default is false*.

$3

Boot Architect :

`js
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 :

`js
module.exports = [{
packagePath: "architect-pg-pool",
pools: {
poolname: {
user: 'dbuser',
password: process.env.DB_PASSWORD,
host: 'db.example.com',
port: 5432,
database: 'dbname',
ssl: {
rejectUnauthorized: false
},
application_name: 'myapp',
max: 2
}
}
}, './routes'];
`

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

`js
{
"name": "routes",
"version": "0.0.1",
"main": "index.js",
"private": true,

"plugin": {
"consumes": ["pgdb"]
}
}
`
Eventually use pg connection in your routes ./routes/index.js :

`js
module.exports = function setup(options, imports, register) {
var rest = imports.rest;
var db = imports.pgdb;

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

register();
};
`


$3

This module supports multiple pools.

Here is how to define 2 different pools :
`js
module.exports = [{
packagePath: "architect-pg-pool",
pools: {
first : {
user: 'postgresuser',
password: 'postgrespwd',
host: 'localhost',
port: 5432,
database: 'dbname'
},
second : {
user: 'postgresuser',
password: 'postgrespwd',
host: 'localhost',
port: 5435,
database: 'otherdb'
},
}
checkOnStartUp : true
}];
`

This will create 2 properties (first and second) in the pgdb object.
`js
module.exports = function setup(options, imports, register) {
var db = imports.pgdb;
// 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();
};
`


$3

* pools object : an object with each keys containing a Pool Config.
* checkOnStartup : boolean, Whether we should try to validate configuration at startup.


#### Pool config

* 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

Please refer to node pg module for details on available options.

$3

The pool object 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.

`js
module.exports = function setup(options, imports, register) {
var db = imports.pgdb;

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.

`js
var JSONSteam = require('JSONStream');

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