Change ActionController::Parameters#require behavior when value is empty

When the value for the required key is empty an ActionController::ParameterMissing is raised which gets caught by ActionController::Base and turned into a 400 Bad Request reply with a message in the body saying the key is missing, which is misleading.

With these changes, ActionController::EmptyParameter will be raised which ActionController::Base will catch and turn into a 400 Bad Request reply with a message in the body saying the key value is empty.

1 files changed, 23 insertions, 9 deletions

diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index acad8a0799..0748d75a69 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -9,8 +9,6 @@ module ActionController
   #   params = ActionController::Parameters.new(a: {})
   #   params.fetch(:b)
   #   # => ActionController::ParameterMissing: param not found: b
-  #   params.require(:a)
-  #   # => ActionController::ParameterMissing: param not found: a
   class ParameterMissing < KeyError
     attr_reader :param # :nodoc:
 
@@ -20,6 +18,20 @@ module ActionController
     end
   end
 
+  # Raised when a required parameter value is empty.
+  #
+  #   params = ActionController::Parameters.new(a: {})
+  #   params.require(:a)
+  #   # => ActionController::EmptyParameter: value is empty for required key: a
+  class EmptyParameter < IndexError
+    attr_reader :param
+
+    def initialize(param)
+      @param = param
+      super("value is empty for required key: #{param}")
+    end
+  end
+
   # Raised when a supplied parameter is not expected.
   #
   #   params = ActionController::Parameters.new(a: "123", b: "456")
@@ -154,20 +166,22 @@ module ActionController
       self
     end
 
-    # Ensures that a parameter is present. If it's present, returns
-    # the parameter at the given +key+, otherwise raises an
-    # <tt>ActionController::ParameterMissing</tt> error.
+    # Ensures that a parameter is present. If it's present and not empty,
+    # returns the parameter at the given +key+, if it's empty raises
+    # an <tt>ActionController::EmptyParameter</tt> error, otherwise
+    # raises an <tt>ActionController::ParameterMissing</tt> error.
     #
     #   ActionController::Parameters.new(person: { name: 'Francesco' }).require(:person)
     #   # => {"name"=>"Francesco"}
     #
-    #   ActionController::Parameters.new(person: nil).require(:person)
-    #   # => ActionController::ParameterMissing: param not found: person
-    #
     #   ActionController::Parameters.new(person: {}).require(:person)
+    #   # => ActionController::EmptyParameter: value is empty for required key: person
+    #
+    #   ActionController::Parameters.new(name: {}).require(:person)
     #   # => ActionController::ParameterMissing: param not found: person
     def require(key)
-      self[key].presence || raise(ParameterMissing.new(key))
+      raise(ActionController::ParameterMissing.new(key)) unless self.key?(key)
+      self[key].presence || raise(ActionController::EmptyParameter.new(key))
     end
 
     # Alias of #require.