How to implement geo-location search in Grails?

Question

I am working on Grails 1.3.2 with MySql. I need to save the latitude and longitude of certain places in the database, and then, based on the user's current location, I need to return elements that are in a certain radius of this location. So, we basically have the following requirements:

• Search for places c-in a given radius of the user's current coordinates
• Provide full-text search. We are currently using search for this.
• Do a combination of a full text search with a given radius of the user's current coordinates.

I studied the various options that we have and wanted to know what your views / suggestions are for their implementation. The various options that we have here are:

• Lucene Spatial Search ( http://wiki.apache.org/lucene-java/SpatialSearch ) and see how to use it with search capability

• Grails Solr Plugin ( http://www.grails.org/plugin/solr ). But this does not return domain objects.

• Grails Stitch Plugin ( http://www.grails.org/plugin/stitches ). There is not much documentation except on the author’s website ( http://www.philliprhodes.com/content/stitches-30-seconds ).

• The MySql spatial extension along with the full text index in all fields of the domain class. If we go along this route, we will not use the search for everyone.

• Integration of Postgres / PostGIS with hibernate-spatial ( http://blog.mollusca.ch/2008/10/4/grails-spatial-data-postgis )

I believe that this is a very basic requirement in any application that integrates with cards.

So, I'm really interested in learning the most appropriate way to implement this functionality.

thanks

Answer 1

(I made a prototype using Long / Lat to search for rows in a radius, but now abandoned this in favor of the GridRef system available in the UK)

As a first step, do not use the WHERE clause based on the calculated field (for example, the actual distance based on the given coordinate and row coordinate).

Instead, try the following:

• Imagine a circle where radius = maximum distance
• Draw a box around it using curved lines of longitude.
• Find items in this field.

In practice, this means:

• determine how many degrees of longitude represents your maximum distance at a given latitude.
• determine how many degrees latitude represents your maximum distance at a given longitude (this factor will be fixed when using the spherical-terrestrial model).
• SELECT * FROM places WHERE long> $ westside AND long <$ eastside AND lat <$ northside and lat> $ southside

This means that you are doing very simple calculations to get an indefinite subset covering the area 30% more than your actual circle. If you also want to add a text search, either SELECT FROM (subquery), or add your text sentence AFTER a simple comparison above, since text queries are expensive.

Answer 2

There is a Grails Spatial plugin . It appears that some of its subpings support search, such as the HDB plugin .