Revert "Merge pull request #9660 from sebasoga/change_strong_parameters_require_behaviour"

This reverts commit c2b5a8e6, reversing
changes made to 1918b12c.

See: https://github.com/rails/rails/pull/9660#issuecomment-27627493

actionpack/lib/action_controller/metal/strong_parameters.rb

@@ -10,6 +10,8 @@ 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:
 
@@ -19,20 +21,6 @@ def initialize(param) # :nodoc:
     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")
@@ -169,22 +157,20 @@ def permit!
       self
     end
 
-    # 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.
+    # 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.
     #
     #   ActionController::Parameters.new(person: { name: 'Francesco' }).require(:person)
     #   # => {"name"=>"Francesco"}
     #
-    #   ActionController::Parameters.new(person: {}).require(:person)
-    #   # => ActionController::EmptyParameter: value is empty for required key: person
+    #   ActionController::Parameters.new(person: nil).require(:person)
+    #   # => ActionController::ParameterMissing: param not found: person
     #
-    #   ActionController::Parameters.new(name: {}).require(:person)
+    #   ActionController::Parameters.new(person: {}).require(:person)
     #   # => ActionController::ParameterMissing: param not found: person
     def require(key)
-      raise(ActionController::ParameterMissing.new(key)) unless self.key?(key)
-      self[key].presence || raise(ActionController::EmptyParameter.new(key))
+      self[key].presence || raise(ParameterMissing.new(key))
     end
 
     # Alias of #require.

actionpack/lib/action_dispatch/middleware/exception_wrapper.rb

@@ -15,8 +15,7 @@ class ExceptionWrapper
       'ActionController::InvalidAuthenticityToken' => :unprocessable_entity,
       'ActionDispatch::ParamsParser::ParseError'   => :bad_request,
       'ActionController::BadRequest'               => :bad_request,
-      'ActionController::ParameterMissing'         => :bad_request,
-      'ActionController::EmptyParameter'           => :bad_request
+      'ActionController::ParameterMissing'         => :bad_request
     )
 
     cattr_accessor :rescue_templates

actionpack/test/controller/parameters/parameters_require_test.rb

@@ -2,14 +2,8 @@
 require 'action_controller/metal/strong_parameters'
 
 class ParametersRequireTest < ActiveSupport::TestCase
-  test "required parameters must be present" do
+  test "required parameters must be present not merely not nil" do
     assert_raises(ActionController::ParameterMissing) do
-      ActionController::Parameters.new(name: {}).require(:person)
-    end
-  end
-
-  test "required parameters can't be blank" do
-    assert_raises(ActionController::EmptyParameter) do
       ActionController::Parameters.new(person: {}).require(:person)
     end
   end

actionpack/test/controller/required_params_test.rb

@@ -5,11 +5,6 @@ def create
     params.require(:book).require(:name)
     head :ok
   end
-
-  def update
-    params.require(:book)
-    head :ok
-  end
 end
 
 class ActionControllerRequiredParamsTest < ActionController::TestCase
@@ -25,20 +20,6 @@ class ActionControllerRequiredParamsTest < ActionController::TestCase
     end
   end
 
-  test "empty required parameters will raise an exception" do
-    assert_raise ActionController::EmptyParameter do
-      put :update, {book: {}}
-    end
-
-    assert_raise ActionController::EmptyParameter do
-      put :update, {book: ''}
-    end
-
-    assert_raise ActionController::EmptyParameter do
-      put :update, {book: nil}
-    end
-  end
-
   test "required parameters that are present will not raise" do
     post :create, { book: { name: "Mjallo!" } }
     assert_response :ok

actionpack/test/dispatch/debug_exceptions_test.rb

@@ -43,8 +43,6 @@ def call(env)
         raise ActionController::UrlGenerationError, "No route matches"
       when "/parameter_missing"
         raise ActionController::ParameterMissing, :missing_param_key
-      when "/required_key_empty_value"
-        raise ActionController::EmptyParameter, :empty_param_key
       else
         raise "puke!"
       end
@@ -128,10 +126,6 @@ def setup
     get "/parameter_missing", {}, {'action_dispatch.show_exceptions' => true}
     assert_response 400
     assert_match(/ActionController::ParameterMissing/, body)
-
-    get "/required_key_empty_value", {}, {'action_dispatch.show_exceptions' => true}
-    assert_response 400
-    assert_match(/ActionController::EmptyParameter/, body)
   end
 
   test "rescue with text error for xhr request" do