PHP PostGIS to GeoJSON - using JSON functions

getfeature2.php

<?php

/** Super Lazy PHP PostGIS to GeoJSON
 * @originalAuthors Leo Hsu and Regina Obe
 * @url http://www.postgresonline.com/journal/archives/267-Creating-GeoJSON-Feature-Collections-with-JSON-and-PostGIS-functions.html
 * @phpImplementation pbabik <https://github.com/pbabik>
 * @license WTFPL 2 <http://www.wtfpl.net/txt/copying/>
 * @requires PostgreSQL 9.3 && PostGIS 2.1 or higher
**/

//DB configuration

$host = 'localhost';
$port = 5432;
$user = 'superuser';
$pass = 'superpassword';
$db = 'superdb';

//connect to the DB
$pdo = new PDO("pgsql:host=$host;port=$port;dbname=$db;user=$user;password=$pass");

//get query parameters with some basic protection against SQL Injection

$table = pg_escape_string($_GET['table']) or die('Missing required parameter: table');
$srid = intval(isset($_GET['srid']) ? $_GET['srid'] : 4326);

//get non-geometry column names

$col_query = "SELECT string_agg('\"'|| column_name::text || '\"',',') FROM information_schema.columns WHERE table_name = '$table'";
$col_query .=" AND column_name NOT IN(SELECT f_geometry_column FROM geometry_columns WHERE f_table_name = '$table')";
$cols = $pdo->query($col_query)->fetch()[0];

//get data as GeometryCollection

$data_query = "SELECT row_to_json(fc) FROM ( SELECT 'FeatureCollection' As type, array_to_json(array_agg(f)) As features";
$data_query .= " FROM (SELECT 'Feature' As type";
$data_query .= ", ST_AsGeoJSON(ST_Transform(lg.geom,$srid))::json As geometry";
$data_query .= ", row_to_json(lp) As properties";
$data_query .=" FROM \"$table\" As lg";
$data_query .= " INNER JOIN (SELECT $cols FROM \"$table\") As lp";
$data_query .= " ON lg.id = lp.id  ) As f )  As fc";

$data = $pdo->query($data_query)->fetch()[0];

header('Content-Type: application/json');
echo $data;