Change the behavior of route defaults

This commit changes route defaults so that explicit defaults are no
longer required where the key is not part of the path. For example:

  resources :posts, bucket_type: 'posts'

will be required whenever constructing the url from a hash such as a
functional test or using url_for directly. However using the explicit
form alters the behavior so it's not required:

  resources :projects, defaults: { bucket_type: 'projects' }

This changes existing behavior slightly in that any routes which
only differ in their defaults will match the first route rather
than the closest match.

Closes #8814

3 files changed, 16 insertions, 6 deletions

diff --git a/actionpack/lib/action_dispatch/journey/route.rb b/actionpack/lib/action_dispatch/journey/route.rb
index b08ac4b4eb..063302e0f2 100644
--- a/actionpack/lib/action_dispatch/journey/route.rb
+++ b/actionpack/lib/action_dispatch/journey/route.rb
@@ -45,7 +45,7 @@ module ActionDispatch
       end
 
       def required_keys
-        path.required_names.map { |x| x.to_sym } + required_defaults.keys
+        required_parts + required_defaults.keys
       end
 
       def score(constraints)
@@ -79,10 +79,13 @@ module ActionDispatch
         @required_parts ||= path.required_names.map { |n| n.to_sym }
       end
 
+      def required_default?(key)
+        (constraints[:required_defaults] || []).include?(key)
+      end
+
       def required_defaults
-        @required_defaults ||= begin
-          matches = parts
-          @defaults.dup.delete_if { |k,_| matches.include?(k) }
+        @required_defaults ||= @defaults.dup.delete_if do |k,_|
+          parts.include?(k) || !required_default?(k)
         end
       end
 
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 43d87e9c0b..6d93f609a6 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -61,8 +61,8 @@ module ActionDispatch
           normalize_path!
           normalize_options!
           normalize_requirements!
-          normalize_defaults!
           normalize_conditions!
+          normalize_defaults!
         end
 
         def to_route
@@ -186,6 +186,13 @@ module ActionDispatch
               @conditions[key] = condition
             end
 
+            @conditions[:required_defaults] = []
+            options.each do |key, required_default|
+              next if segment_keys.include?(key) || IGNORE_OPTIONS.include?(key)
+              next if Regexp === required_default
+              @conditions[:required_defaults] << key
+            end
+
             via_all = options.delete(:via) if options[:via] == :all
 
             if !via_all && options[:via].blank?
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index 931ad372a8..c72310cca3 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -421,7 +421,7 @@ module ActionDispatch
         end
 
         conditions.keep_if do |k, _|
-          k == :action || k == :controller ||
+          k == :action || k == :controller || k == :required_defaults ||
             @request_class.public_method_defined?(k) || path_values.include?(k)
         end
       end