Ruby on rails Geokit：未定义的方法“key”和#x27；零级：零级

我已安装以下gems：

geokit（1.8.4）
geokit导轨（2.0.1）

我要映射的模型：

class Merchant < ActiveRecord::Base
  attr_accessible :name, :geolat, :geolon, :lat, :lng


  acts_as_mappable :default_units => :miles, 
               :default_formula => :sphere, 
               :distance_field_name => :distance,
               :lat_column_name => :lat,
               :lng_column_name => :lng

end

结束

当我启动本地服务器时

NoMethodError in MerchantsController#index

undefined method `key?' for nil:NilClass

这是我的商品控制器索引

更新：StackTrace

---

向我们展示整个stacktrace会很有帮助只是更新了一个问题，谢谢您在merchants表中有记录吗？是的，merchants表中有记录。如果我回滚我在帖子中提到的所有更改，一切都会正常工作。在尝试其他宝石之前，我很想找到一个解决方案。请告诉我一些建议，我一直在寻找解决方法，但运气不佳

NoMethodError in MerchantsController#index

undefined method `key?' for nil:NilClass

 def index
    @merchants = Merchant.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @merchants }
    end
  end

Started GET "/" for 127.0.0.1 at 2014-03-12 13:47:31 -0600

NoMethodError (undefined method `key?' for nil:NilClass):
actionpack (3.2.11) lib/action_controller/metal/hide_actions.rb:36:in `visible_action?'
actionpack (3.2.11) lib/action_controller/metal/hide_actions.rb:18:in `method_for_action'
actionpack (3.2.11) lib/action_controller/metal/implicit_render.rb:14:in `method_for_action'
actionpack (3.2.11) lib/action_controller/metal/compatibility.rb:61:in `method_for_action'
actionpack (3.2.11) lib/abstract_controller/base.rb:115:in `process'
actionpack (3.2.11) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.2.11) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.11) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.11) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:73:in `call'
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:36:in `call'
journey (1.0.4) lib/journey/router.rb:68:in `block in call'
journey (1.0.4) lib/journey/router.rb:56:in `each'
journey (1.0.4) lib/journey/router.rb:56:in `call'
actionpack (3.2.11) lib/action_dispatch/routing/route_set.rb:601:in `call'
warden (1.2.3) lib/warden/manager.rb:35:in `block in call'
warden (1.2.3) lib/warden/manager.rb:34:in `catch'
warden (1.2.3) lib/warden/manager.rb:34:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.4.5) lib/rack/etag.rb:23:in `call'
rack (1.4.5) lib/rack/conditionalget.rb:25:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.5) lib/rack/session/abstract/id.rb:210:in `context'
rack (1.4.5) lib/rack/session/abstract/id.rb:205:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/cookies.rb:341:in `call'
activerecord (3.2.11) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.11) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.11) lib/active_support/callbacks.rb:405:in `_run__4293249038777371623__call__703614483466287418__callbacks'
activesupport (3.2.11) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.11) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.11) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.11) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.11) lib/rails/rack/logger.rb:32:in `call_app'
railties (3.2.11) lib/rails/rack/logger.rb:16:in `block in call'
activesupport (3.2.11) lib/active_support/tagged_logging.rb:22:in `tagged'
railties (3.2.11) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.5) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.5) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.11) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.5) lib/rack/lock.rb:15:in `call'
actionpack (3.2.11) lib/action_dispatch/middleware/static.rb:62:in `call'
railties (3.2.11) lib/rails/engine.rb:479:in `call'
railties (3.2.11) lib/rails/application.rb:223:in `call'
rack (1.4.5) lib/rack/content_length.rb:14:in `call'
railties (3.2.11) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.5) lib/rack/handler/webrick.rb:59:in `service'
/Users/andreucasadella/.rvm/rubies/ruby-1.9.3-p362/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/Users/andreucasadella/.rvm/rubies/ruby-1.9.3-p362/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/Users/andreucasadella/.rvm/rubies/ruby-1.9.3-p362/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

Rendered /Users/andreucasadella/.rvm/gems/ruby-1.9.3-p362/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.7ms)
Rendered /Users/andreucasadella/.rvm/gems/ruby-1.9.3-p362/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (1.4ms)
Rendered /Users/andreucasadella/.rvm/gems/ruby-1.9.3-p362/gems/actionpack-3.2.11/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (11.5ms)