Implements require with multiple parameters

Normal use is unchanged.

When used with multiple parameters the error raised in case a
parameter is missing lists all the missing parameters.

Returns the params hash if no required parameters are missing.

README.md

@@ -70,6 +70,16 @@ This declaration whitelists the `name`, `emails` and `friends` attributes. It is
 
 Thanks to Nick Kallen for the permit idea!
 
+## Requiring multiple values
+
+In some cases you might want to require several parameters to be present before proceeding, such as for an API where the params might be a flat hash. You can use `require` to do this:
+
+``` ruby
+params.require(:username, :password).permit(:version)
+```
+
+When used with multiple inputs `require` raises a `ActionController::MissingParameter` error with *all* the missing attributes specified in the message. If no values are missing the params hash is returned unmodified.
+
 ## Handling of Unpermitted Keys
 
 By default parameter keys that are not explicitly permitted will be logged in the development and test environment. In other environments these parameters will simply be filtered out and ignored.

lib/action_controller/parameters.rb

@@ -22,7 +22,7 @@ class UnpermittedParameters < IndexError
 
     def initialize(params)
       @params = params
-      super("found unpermitted parameters: #{params.join(", ")}")
+      super("found unpermitted parameter(s): #{params.join(", ")}")
     end
   end
 
@@ -51,8 +51,12 @@ def permit!
       self
     end
 
-    def require(key)
-      self[key].presence || raise(ActionController::ParameterMissing.new(key))
+    def require(*keys)
+      if keys.many?
+        require_multiple(keys)
+      else
+        require_single(keys)
+      end
     end
 
     alias :required :require
@@ -98,6 +102,20 @@ def dup
     end
 
     protected
+      def require_single(keys)
+        key = keys.first 
+        self[key].presence || raise(ActionController::ParameterMissing.new(key))
+      end
+
+      def require_multiple(keys)
+        missing_keys = keys.select do |key|
+          self[key].blank?
+        end
+
+        raise(ActionController::ParameterMissing.new(missing_keys.join(', '))) if missing_keys.compact.any?
+        self
+      end
+
       def convert_value(value)
         if value.class == Hash
           self.class.new_from_hash_copying_default(value)
@@ -109,7 +127,6 @@ def convert_value(value)
       end
 
     private
-
       def convert_hashes_to_parameters(key, value)
         if value.is_a?(Parameters) || !value.is_a?(Hash)
           value
@@ -217,7 +234,7 @@ def unpermitted_parameters!(params)
         unpermitted_keys = unpermitted_keys(params)
 
         if unpermitted_keys.any?  
-          case self.class.action_on_unpermitted_parameters  
+          case self.class.action_on_unpermitted_parameters
           when :log
             name = "unpermitted_parameters.action_controller"
             ActiveSupport::Notifications.instrument(name, :keys => unpermitted_keys)
@@ -237,7 +254,7 @@ module StrongParameters
 
     included do
       rescue_from(ActionController::ParameterMissing) do |parameter_missing_exception|
-        render :text => "Required parameter missing: #{parameter_missing_exception.param}", :status => :bad_request
+        render :text => "Required parameter(s) missing: #{parameter_missing_exception.param}", :status => :bad_request
       end
     end
 

test/action_controller_required_params_test.rb

@@ -25,6 +25,6 @@ class ActionControllerRequiredParamsTest < ActionController::TestCase
 
   test "missing parameters will be mentioned in the return" do
     post :create, { :magazine => { :name => "Mjallo!" } }
-    assert_equal "Required parameter missing: book", response.body
+    assert_match "book", response.body
   end
 end

test/log_on_unpermitted_params_test.rb

@@ -16,7 +16,7 @@ def teardown
       :fishing => "Turnips"
     })
 
-    assert_logged("Unpermitted parameters: fishing") do
+    assert_logged("Unpermitted parameter(s): fishing") do
       params.permit(:book => [:pages])
     end
   end
@@ -26,7 +26,7 @@ def teardown
       :book => { :pages => 65, :title => "Green Cats and where to find then." }
     })
 
-    assert_logged("Unpermitted parameters: title") do
+    assert_logged("Unpermitted parameter(s): title") do
       params.permit(:book => [:pages])
     end
   end

test/parameters_require_test.rb

@@ -7,4 +7,29 @@ class ParametersRequireTest < ActiveSupport::TestCase
       ActionController::Parameters.new(:person => {}).require(:person)
     end
   end
+
+  test "permit multiple required parameters" do
+    params = ActionController::Parameters.new(:username => 'user', :password => '<3<3<3<3')
+    assert_nothing_raised(ActionController::ParameterMissing) do
+      params.require(:username, :password)
+    end
+
+    assert params.has_key?(:username)
+    assert params.has_key?(:password)
+  end
+
+  test "multiple required parameters must be present not merely not nil" do
+    params = ActionController::Parameters.new(:username => '', :password => nil)
+    assert_raises(ActionController::ParameterMissing) do
+      params.require(:username, :password)
+    end
+  end
+
+  test "all parameters are returned after required with multiple parameters" do
+    params = ActionController::Parameters.new(:username => 'user', :password => '<3<3<3<3', :version => 1)
+
+    params.require(:username, :password)
+
+    assert params.has_key?(:version)
+  end
 end