the router allows String contraints.

Closes #9432.

1 files changed, 17 insertions, 11 deletions

diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 817480c7ae..dba9ccbfa5 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -124,15 +124,7 @@ module ActionDispatch
           def normalize_requirements!
             constraints.each do |key, requirement|
               next unless segment_keys.include?(key) || key == :controller
-
-              if requirement.source =~ ANCHOR_CHARACTERS_REGEX
-                raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
-              end
-
-              if requirement.multiline?
-                raise ArgumentError, "Regexp multiline option is not allowed in routing requirements: #{requirement.inspect}"
-              end
-
+              verify_regexp_requirement(requirement) if requirement.is_a?(Regexp)
               @requirements[key] = requirement
             end
 
@@ -145,6 +137,16 @@ module ActionDispatch
             end
           end
 
+          def verify_regexp_requirement(requirement)
+            if requirement.source =~ ANCHOR_CHARACTERS_REGEX
+              raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
+            end
+
+            if requirement.multiline?
+              raise ArgumentError, "Regexp multiline option is not allowed in routing requirements: #{requirement.inspect}"
+            end
+          end
+
           def normalize_defaults!
             @defaults.merge!(scope[:defaults]) if scope[:defaults]
             @defaults.merge!(options[:defaults]) if options[:defaults]
@@ -425,11 +427,15 @@ module ActionDispatch
         #      end
         #
         # [:constraints]
-        #   Constrains parameters with a hash of regular expressions or an
-        #   object that responds to <tt>matches?</tt>
+        #   Constrains parameters with a hash of regular expressions
+        #   or an object that responds to <tt>matches?</tt>. In addition, constraints
+        #   other than path can also be specified with any object
+        #   that responds to <tt>===</tt> (eg. String, Array, Range, etc.).
         #
         #     match 'path/:id', constraints: { id: /[A-Z]\d{5}/ }
         #
+        #     match 'json_only', constraints: { format: 'json' }
+        #
         #     class Blacklist
         #       def matches?(request) request.remote_ip == '1.2.3.4' end
         #     end