def block in rake task

Update: Gotcha

This potentially adds the method to global scope and will conflict with any other method with the same name. Look at @Hula_Zell's answer https://stackoverflow.com/a/44294243/584440 for a better way.

Original answer

You are defining the method inside the rake task. For getting the function, you should define outside the rake task (outside the task block). Try this:

include Geokit::Geocodersnamespace :geocode do  desc "Geocode to get latitude, longitude and address"  task :all => :environment do    @spot = Spot.find(:first)    if @spot.latitude.blank? && !@spot.address.blank?      puts address_geo    end  end  def address_geo    arr = []    arr << address if @spot.address    arr << city if @spot.city    arr << country if @spot.country    arr.reject{|y|y==""}.join(", ")  endend

Careful: Methods defined in rake files end up defined on the global namespace.

I would propose to extract the methods into a module or class. This is because methods defined in rake files end up defined on the global namespace. i.e. they can then be called from anywhere, not just within that rake file (even if it is namespaced!).

This also means that if you have two methods with the same name in two different rake tasks, one of them will be overwritten without you knowing it. Very deadly.

A great explanation is available here: https://kevinjalbert.com/defined_methods-in-rake-tasks-you-re-gonna-have-a-bad-time/

You can use a Proc to get the same effect without having a global method declaration. e.g.,

include Geokit::Geocodersnamespace :geocode do  desc "Geocode to get latitude, longitude and address"  task :all => :environment do    address_geo = Proc.new do      arr = []      arr << address if @spot.address      arr << city if @spot.city      arr << country if @spot.country      arr.reject{|y|y==""}.join(", ")    end    @spot = Spot.find(:first)    if @spot.latitude.blank? && !@spot.address.blank?      puts address_geo.call    end  endend