Geocoding with Google Maps and the Zend Framework

Rob — Sat, 24 Apr 2010 17:51:40 +0000

Download Example Files:

Maps are a great way to engage your users and visualize data, but it can be a little tricky to setup. Here I will walk you through the steps needed to get a map up and running.

Sign Up

Apply for a Google Maps API Key (free) here using your domain without a subdomain or www (this will allow you to use key with or without www and on subdomains): http://code.google.com/apis/maps/signup.html

Configuration

Put the API key in your configuration file (application.ini, config.ini, etc.) like this:

[google]
google_map_key =  YOUR_KEY

Bootstrapping

~~In your index.php file, add the following code:~~
As a concerned user pointed out, that is terrible practice and was a remnant of my first tinkerings with ZF. You should place this code in your Bootstrap.php file:

protected function initGoogle(){
	defined('CONFIG_PATH') or define('CONFIG_PATH', APPLICATION_PATH . '/configs/application.ini');
	Zend_Registry::set('google',  new Zend_Config_Ini(CONFIG_PATH, 'google'));
}

This will add your api key to the registry so that it can be accessed throughout your application.

Model

In your models directory, create a new class called ‘Geocoder.php’. This will be the file that contains the application logic for retreiving coordinates on a given location.

models/Geocoder.php


class Geocoder{
    protected $key;

    public function __construct($api_key)
    {
        $this->key = $api_key;
    }

    public function _getGeocodedLatitudeAndLongitude($address)
    {
        $client = new Zend_Http_Client();
        $client->setUri($this->getGeocodingUri());
        $client->setParameterGet('q', urlencode($address))
               ->setParameterGet('output', 'json')
               ->setParameterGet('sensor', 'false')
               ->setParameterGet('key', $this->key);

        $result = $client->request('GET');
        $response = Zend_Json_Decoder::decode($result->getBody(),
                    Zend_Json::TYPE_OBJECT);
        return $response;
    }

    public function getCoordinates($address)
    {
        $response = $this->_getGeocodedLatitudeAndLongitude($address);
        if(isset($response->Placemark[0]->Point->coordinates[1])){
             return array(
                'lat' => $response->Placemark[0]->Point->coordinates[1],
                'lon' => $response->Placemark[0]->Point->coordinates[0]
            );
        } else {
			return null;
		}
    }

    private function getGeocodingUri()
    {
        return 'http://maps.google.com/maps/geo';
    }
}
?>

Usage

Alright, that was pretty easy. Now we just have to implement this in our controller. Here is a sample model that uses the Geocoder class to return geotagged User objects.
models/User.php

class User extends Zend_Db_Table_Abstract{
	protected $_name = 'users';
	protected $key;
	protected $geocoder;

	public function init()
	{
		$this->key = Zend_Registry::get('google')->google_map_key;
		$this->geocoder = new Geocoder($this->key);

	}
	public function getUsersAndGeocode()
	{
		$result = $this->fetchAll();

		$users    = $result->_toArray();
		foreach($users as $user)
		{
			$address = "{$user['address']} {$user['city']} {$user['state']} {$user['zip']}";

			$latlon = $this->geocoder->getCoordinates($address);
			if($latlon)
			{
				$user['lat'] = $latlon['lat'];
				$user['lon'] = $latlon['lon'];
			}
		}
		return $users;
	}

}
?>

The controller part is a little too easy. We will setup a reference to our user table and create a map action. Within the map action we get all of users and geocode them. We pass that collection to our view. This file should be located here:
controllers/UserController.php

class UserController extends Zend_Controller_Action{
	protected $user_table;
	public function init()
	{
		//database connectivity stuff is up to you

		$this->user_table = new User();
	}
	public function mapAction()
	{
		$this->view->api_key = Zend_Registry::get('google')->google_map_key;
		$users = $this->user_table->getUsersAndGeocode();
		$this->view->users = $users;
	}
}
?>

And finally, the view. Here we will create our map div, load the Google Maps API (don’t forget to sub out your key in the script src). We are using a custom marker here (personIcon); you can add your own image here by changing the path to your image. I recommend the image be pretty small with a transparent background. Given our current setup, this file would be located at this path:
views/scripts/user/map.phtml

Post a comment if you have any questions

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