WordPress plugin: Geo Query

###Description

This plugin adds a support for the geo_query part of the WP_query.

It uses the Haversine SQL implementation by Ollie Jones (see here).

The plugin works on PHP 5.3+.

It supports the GitHub Updater.

Activate the plugin and you can use the geo_query parameter in all your WP_Query queries.

###Example:

Here's an example of the supported input parameters of the geo_query part:

$args = array(
    'post_type'           => 'post',    
    'posts_per_page'      => 10,
    'ignore_sticky_posts' => true,
    'orderby'             => array( 'title' => 'DESC' ),
    'geo_query' => array(
        'lat'                =>  64,                                // Latitude point
        'lng'                =>  -22,                               // Longitude point
        'lat_meta_key'       =>  'my_lat',                          // Meta-key for the latitude data
        'lng_meta_key'       =>  'my_lng',                          // Meta-key for the longitude data 
        'radius'             =>  150,                               // Find locations within a given radius (km)
        'order'              =>  'DESC',                            // Order by distance
        'distance_unit'      =>  111.045,                           // Default distance unit (km per degree). Use 69.0 for statute miles per degree.
        'context'            => '\\Birgir\\Geo\\GeoQueryHaversine', // Default implementation, you can use your own here instead.
    ),
);
$query = new WP_Query( $args );

###Notes on the parameters:

• The plugin assumes we store the latitudes and longitudes as custom fields ( post meta), so we need to tell the query about meta keys with the 'lat_meta_key' and 'lng_meta_key' parameters.

• Skipping the 'radius' parameter means that no distance filtering will take place.

• If we use the 'order' parameter within the 'geo_query', then it will be prepended to the native 'orderby' parameter.

• The 'distance_unit' parameter should be 69.0 for distance in statute miles, else 111.045 for distance in kilometers.

• If we want to use the optimized Haversine version by Ollie Jones, we use:

    'context' => '\\Birgir\\Geo\\GeoQueryHaversineOptimized'
  

  Notice that on our current plugin setup (i.e. fetching data from the LONGTEXT post meta fields) this isn't more performant than the default GeoQueryHaversine class.

  A future work could be to use a custom table with indexes, for the optimization to work.

• If we create our own implementation of the Haversine formula, for example the GeoQueryCustom class, we just have to make sure it implements the GeoQueryInterface interface:

    'context' => 'GeoQueryCustom'
  

###Feedback

Any suggestions are welcomed.

###Changelog 0.0.3 (2015-04-29)

• Fixed #2. Fixed a typo. Props @Ben764 and @con322.

0.0.2 (2015-03-10)

• Added: Support for the GitHub Updater.
• Updated: README.md
• Changed: Use distance_value instead of distance_in_km in SQL, since we can use miles by changing the distance_unit parameter.

0.0.1 - Init