Acts_as_locateable

There seems to be quite a plethora of Ruby/Rails libraries appearing aiming to simplify handling geography and distances. In some cases these libraries do quite distinct things (zip codes vs. longitude/latitude, map output vs. distance calculations) but they’re frequently lumped together and it’s difficult to tell which will be best to use in your projects. I’ve used several of these projects and have previously blogged about YM4R and acts_as_locateable, but I’m still not sure which I’d pick for new projects. So I thought it would be helpful to try to put together a comparison of which libraries offer what functionality. Here I’ll just offer a quick chart, but I’m hoping to write them up in a bit more detail over the coming days/weeks. If there’s sufficient interest, I’d consider moving this out to a wiki for more general use. ...

Wednesday’s post on acts_as_locateable didn’t do much to explain what the patch to the plugin’s methods was doing to allow us to pass extra arguments to ActiveRecord#find. The secret is in the *, or array argument. A normal method will have a fixed number of arguments: def simple_method(first, second, third) puts "#{first} : #{second} : #{third}" end simple_method('one', 'two', 'three') >> one : two : three and sometimes we can develop that by allowing default values for those arguments: ...

There have been quite a few geographically-themed Rails plugins emerging over the past few months and I decided it was time to try out acts_as_locateable. Acts_as_locateable is based on ZipCodeSearch. It loads in a database mapping US zip codes to coordinates and then adds convenience methods to ActiveRecord objects that let you search by distance. eg. Event.find_within_radius(50, '49503') will return all events within 50 miles of me. What the standard plugin doesn’t allow is the passing in of more search parameters. So if I wanted to limit that search to future events I’d have to retrieve all the results and iterate over them. In a large system that could be very inefficient. ...