def block in rake task

I got undefined local variable or method 'address_geo' for main:Object with the following rake task. What's the problem with it?

include Geokit::Geocoders

namespace :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

    def address_geo
      arr = []
      arr << address if @spot.address
      arr << city i开发者_如何学Cf @spot.city
      arr << country if @spot.country
      arr.reject{|y|y==""}.join(", ")
    end
  end
end

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::Geocoders

namespace :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(", ")
  end
end

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::Geocoders

namespace :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
  end
end