Geocoding in CakePHP

By Nate aka "nate"

A couple of weeks ago, I was building an event management system which required that people be able to search events near them. I found several existing solutions, but none that I could integrate as easily as a proper Cake extension.

Introduction

The Geocoded Behavior for CakePHP is the simplest and most powerful way to integrate geocoding into your CakePHP application. It integrates with both Google Maps and Yahoo! Local geocoding services (and is extensible to allow for the inclusion of other services), it automatically caches geocode data, and best of all, it can be implemented in just 3 lines of code.

Downloading & Setup

The Geocoded Behavior is featured in the initial release of the Mashup API Project, which is a new repository for CakePHP components, behaviors and helpers which integrate web service APIs. You can download the latest release of the Mashup API Project here: https://cakeforge.org/frs/?group_id=161

Once you have downloaded and unzipped the release, copy geocoded.php from the /models/behaviors folder into your application's /models/behaviors folder. Then, import /config/sql/geocodes.php into your application's database. Finally, you need an Application ID (Yahoo! Local) or an API key (Google Maps) in order to integrate the service of your choice. You can get your keys here:

1. Google Maps API Key - http://www.google.com/apis/maps/signup.html
2. Yahoo! Local App ID - http://search.yahooapis.com/webservices/register_application

A Simple Example

Let's start by verifying that our service works, and we're able to connect to it using our key. We'll create a simple model called Location, using the following SQL:

SQL:

Download code
CREATE TABLE `locations` (
`id` int(11) unsigned NOT NULL auto_increment,
`name` varchar(255) default NULL,
`addr1` varchar(255) default NULL,
`addr2` varchar(255) default NULL,
`city` varchar(255) default NULL,
`state` varchar(255) default NULL,
`zip` varchar(5) NOT NULL default '',
`lat` float default NULL,
`lon` float default NULL,
`created` datetime default NULL,
`modified` datetime default NULL,
PRIMARY KEY (`id`)
);


Then we'll create our model, designating that we want to enable it for geocoding:

Model Class:

Download code
class Location extends AppModel {

var $name = 'Location';

var $actsAs = array('Geocoded' => array(
'key' => 'ABQIAAAAn0kmVahg_WhO0jCT8Z8MkBT2yXp_ZAY8_u....'
));
}

?>

Replace the value of 'key' with your Google Map API key or Yahoo! App ID (the default API key for the localhost domain is ABQIAAAAn0kmVahg_WhO0jCT8Z8MkBT2yXp_ZAY8_ufC3CFXhHIE1NvwkxS-Zl837z60cpTjKeSeelhEJVmNOQ).

Then, create a controller that uses the Location model, and add the following to an action:

Controller Class:

Download code pr($this->Location->geocode('1600 Pennsylvania Ave. Washington DC USA'));
?>

You should then see an array similar to the following:

Download code
Array
(
[lat] => 38.898758
[lon] => -77.037691
)


If DEBUG is set to 2 or higher, you should also see the following queries:

SQL:

Download code
SELECT `Geocode`.`address`, `Geocode`.`lon`, `Geocode`.`lat` FROM `geocodes` AS `Geocode` WHERE `Geocode`.`address` = '1600 pennsylvania ave. washington dc usa' LIMIT 1
INSERT INTO `geocodes` (`address`,`lat`,`lon`) VALUES ('1600 pennsylvania ave. washington dc usa', 38.898758,-77.037691)


Before querying the web service, the Geocoded behavior checks the cache to see if a lookup on this address has already been performed. Then, after successfully retrieving the results from the web service, it saves those results to the cache table. From now on, any lookups for that address will be read from the cache.

Getting Fancy

Besides strings, the geocode() method will also accept arrays, from which it will attempt to extract address information. This makes it extremely easy to add geo-data to models which include address data. The list of extractable fields is as follows:
Download code
'street', 'address', 'addr', 'address1', 'addr1', 'address2', 'address2', 'apt', 'city', 'state', 'zip', 'zipcode', 'zip_code'


Using beforeSave(), we can automatically save geocoded coordinates to our Location model every time a record is created or updated:

Model Class:

Download code
class Location extends AppModel {

var $name = 'Location';

var $actsAs = array('Geocoded' => array(
'key' => 'ABQIAAAAn0kmVahg_WhO0jCT8Z8MkBT2yXp_ZAY8_u....'
));

function beforeSave() {
if ($coords = $this->geocode($this->data)) {
$this->set($coords);
}
return true;
}
}

?>

This will save any valid coordinate set, based on the data provided. The Location model uses the field combination of 'addr1, 'addr2', 'city', 'state', 'zip' to create the address string. Some other valid combinations are:

1. street, city, state
2. address, city, state, zip
3. addr, apt, city, zipcode
4. city, zip_code
5. zipcode
6. And so on.

Any other valid combination of fields from the list will work just fine. You can also customize the field names in the Location model which are used to store the coordinate data, if, for example you wanted to use the field names 'latitude' and 'longitude'.

The full list of configuration options for the Geocoded behavior is as follows:

• lookup - The name of the lookup service to use. Currently available options are 'google' and 'yahoo'. Defaults to 'google'.
• key - The Google Maps API key or Yahoo! Local App ID for your application
• cacheTable - The name of the table to use when caching geocode data. Defaults to 'geocodes'. Alternatively, you can create a Geocode model which will be used for all saves and lookups, in which case this setting will be ignored.
• fields - An array containing the field names to use for latitude and longitude data. These should match the field names of your geocoded model. Defaults to array('lat', 'lon').

Searching

After creating a few locations, we can search for ones in our area. The Geocoded Behavior includes a method called findAllByDistance(), which allows you to search for records within a given distance of a certain point. We can first get the coordinates of our search location, then do the search. The findAllByDistance() method can be called in one of two ways:

Download code
findAllByDistance($coords, $distance);
- or -
findAllByDistance($x, $y, $distance);


In the first example, $coords is an array containing longitude and latitude values (in that order). In the second example, $x and $y are longitude and latitude values, respectively. In both examples, $distance is the search radius in miles.

Putting this into practice, we can do something like the following:

Controller Class:

Download code $youAreHere = $this->Location->geocode("132 Tremont St. Boston, MA");
$locations = $this->Location->findAllByDistance($youAreHere, 5);
?>

This will find all the Location records within 5 miles of me. Alternatively, you could create a form based on the address fields in the Location model, and run your searches dynamically:

Controller Class:

Download code if (!empty($this->data)) {
$youAreHere = $this->Location->geocode($this->data);
$locations = $this->Location->findAllByDistance($youAreHere, 5);
}
?>

Adding location searching in CakePHP is now as simple as that.

Future versions of the Geocoded Behavior will generate a virtual 'distance' field within your query, allowing you to do sorting and more advanced filtering and comparison. Other future plans include setting a default measurement unit, with automatic unit converstions, as well as setting default array keys from which to generate addresses, as well as methods for facilitating the integration of other geocoding APIs.

Stay tuned for more fun web APIs, and check out the official CakePHP Mashup API Project at https://cakeforge.org/projects/mashup/, where more code examples and API integrations will be appearing shortly.