1 files changed, 33 insertions, 12 deletions
diff --git a/actionpack/lib/action_dispatch/journey/formatter.rb b/actionpack/lib/action_dispatch/journey/formatter.rb
index c0566c6fc9..d8bb10ffab 100644
--- a/actionpack/lib/action_dispatch/journey/formatter.rb
+++ b/actionpack/lib/action_dispatch/journey/formatter.rb
@@ -14,7 +14,7 @@ module ActionDispatch
 
       def generate(name, options, path_parameters, parameterize = nil)
         constraints = path_parameters.merge(options)
-        missing_keys = []
+        missing_keys = nil # need for variable scope
 
         match_route(name, constraints) do |route|
           parameterized_parts = extract_parameterized_parts(route, options, path_parameters, parameterize)
@@ -25,22 +25,22 @@ module ActionDispatch
           next unless name || route.dispatcher?
 
           missing_keys = missing_keys(route, parameterized_parts)
-          next unless missing_keys.empty?
+          next if missing_keys && !missing_keys.empty?
           params = options.dup.delete_if do |key, _|
             parameterized_parts.key?(key) || route.defaults.key?(key)
           end
 
           defaults       = route.defaults
           required_parts = route.required_parts
-          parameterized_parts.delete_if do |key, value|
-            value.to_s == defaults[key].to_s && !required_parts.include?(key)
+          parameterized_parts.keep_if do |key, value|
+            defaults[key].nil? || value.to_s != defaults[key].to_s || required_parts.include?(key)
           end
 
           return [route.format(parameterized_parts), params]
         end
 
         message = "No route matches #{Hash[constraints.sort_by{|k,v| k.to_s}].inspect}"
-        message << " missing required keys: #{missing_keys.sort.inspect}" unless missing_keys.empty?
+        message << " missing required keys: #{missing_keys.sort.inspect}" if missing_keys && !missing_keys.empty?
 
         raise ActionController::UrlGenerationError, message
       end
@@ -54,12 +54,12 @@ module ActionDispatch
         def extract_parameterized_parts(route, options, recall, parameterize = nil)
           parameterized_parts = recall.merge(options)
 
-          keys_to_keep = route.parts.reverse.drop_while { |part|
+          keys_to_keep = route.parts.reverse_each.drop_while { |part|
             !options.key?(part) || (options[part] || recall[part]).nil?
           } | route.required_parts
 
-          (parameterized_parts.keys - keys_to_keep).each do |bad_key|
-            parameterized_parts.delete(bad_key)
+          parameterized_parts.delete_if do |bad_key, _|
+            !keys_to_keep.include?(bad_key)
           end
 
           if parameterize
@@ -110,15 +110,36 @@ module ActionDispatch
           routes
         end
 
+        module RegexCaseComparator
+          DEFAULT_INPUT = /[-_.a-zA-Z0-9]+\/[-_.a-zA-Z0-9]+/
+          DEFAULT_REGEX = /\A#{DEFAULT_INPUT}\Z/
+
+          def self.===(regex)
+            DEFAULT_INPUT == regex
+          end
+        end
+
         # Returns an array populated with missing keys if any are present.
         def missing_keys(route, parts)
-          missing_keys = []
+          missing_keys = nil
           tests = route.path.requirements
           route.required_parts.each { |key|
-            if tests.key?(key)
-              missing_keys << key unless /\A#{tests[key]}\Z/ === parts[key]
+            case tests[key]
+            when nil
+              unless parts[key]
+                missing_keys ||= []
+                missing_keys << key
+              end
+            when RegexCaseComparator
+              unless RegexCaseComparator::DEFAULT_REGEX === parts[key]
+                missing_keys ||= []
+                missing_keys << key
+              end
             else
-              missing_keys << key unless parts[key]
+              unless /\A#{tests[key]}\Z/ === parts[key]
+                missing_keys ||= []
+                missing_keys << key
+              end
             end
           }
           missing_keys