Properly detect error in MaxMind response.

lib/geocoder/lookups/maxmind.rb

@@ -15,9 +15,12 @@ module Geocoder::Lookup
 
     private # ---------------------------------------------------------------
 
-    def service_code
+    ##
+    # Return the name of the configured service, or raise an exception.
+    #
+    def configured_service!
       if s = configuration[:service] and services.keys.include?(s)
-        services[s]
+        return s
       else
         raise(
           Geocoder::ConfigurationError,
@@ -28,6 +31,19 @@ module Geocoder::Lookup
       end
     end
 
+    def service_code
+      services[configured_service!]
+    end
+
+    def service_response_fields_count
+      Geocoder::Result::Maxmind.field_names[configured_service!].size
+    end
+
+    def data_contains_error?(parsed_data)
+      # if all fields given then there is an error
+      parsed_data.size == service_response_fields_count and !parsed_data.last.nil?
+    end
+
     ##
     # Service names mapped to code used in URL.
     #
@@ -45,7 +61,7 @@ module Geocoder::Lookup
       return [reserved_result] if query.loopback_ip_address?
       doc = fetch_data(query)
       if doc and doc.is_a?(Array)
-        if doc.last.nil?
+        if !data_contains_error?(doc)
           return [doc]
         elsif doc.last == "INVALID_LICENSE_KEY"
           raise_error(Geocoder::InvalidApiKey) || warn("Invalid MaxMind API key.")

lib/geocoder/results/maxmind.rb

@@ -71,7 +71,7 @@ module Geocoder::Result
     #
     def service_name
       self.class.field_names.to_a.each do |n,f|
-        return n if f.size == @data.size
+        return n if (@data.size..@data.size+1).include?(f.size)
       end
       nil
     end

test/fixtures/maxmind_24_24_24_21

-US,
+US

test/fixtures/maxmind_24_24_24_22

-US,NY,Jamaica,40.6915,-73.8057,
+US,NY,Jamaica,40.6915,-73.8057

test/fixtures/maxmind_24_24_24_23

-US,NY,Jamaica,,40.6915,-73.8057,501,718,"Road Runner","Road Runner",
+US,NY,Jamaica,,40.6915,-73.8057,501,718,"Road Runner","Road Runner"

test/fixtures/maxmind_24_24_24_24

-US,"United States",NY,"New York",Jamaica,40.6915,-73.8057,501,718,America/New_York,NA,,"Road Runner","Road Runner",rr.com,"AS11351 Road Runner HoldCo LLC",Cable/DSL,residential,779,99,37,76,,
+US,"United States",NY,"New York",Jamaica,40.6915,-73.8057,501,718,America/New_York,NA,,"Road Runner","Road Runner",rr.com,"AS11351 Road Runner HoldCo LLC",Cable/DSL,residential,779,99,37,76,35

test/test_helper.rb

@@ -239,7 +239,7 @@ end
 class Test::Unit::TestCase
 
   def setup
-    Geocoder.configure(:maxmind => {:service => :omni})
+    Geocoder.configure(:maxmind => {:service => :city_isp_org})
   end
 
   def teardown