Add support for blacklisting certain content_types

lib/paperclip/validators/attachment_content_type_validator.rb

@@ -8,21 +8,41 @@ module Paperclip
 
       def validate_each(record, attribute, value)
         attribute = "#{attribute}_content_type".to_sym
-        value = record.send(:read_attribute_for_validation, attribute)
-        allowed_types = [options[:content_type]].flatten
+        value = record.send :read_attribute_for_validation, attribute
 
         return if (value.nil? && options[:allow_nil]) || (value.blank? && options[:allow_blank])
 
-        if allowed_types.none? { |type| type === value }
-          record.errors.add(attribute, :invalid, options.merge(
-            :types => allowed_types.join(', ')
-          ))
+        validate_whitelist(record, attribute, value)
+        validate_blacklist(record, attribute, value)
       end
+
+      def validate_whitelist(record, attribute, value)
+        if allowed_types.present? && allowed_types.none? { |type| type === value }
+          mark_invalid record, attribute, allowed_types
+        end
+      end
+
+      def validate_blacklist(record, attribute, value)
+        if forbidden_types.present? && forbidden_types.any? { |type| type === value }
+          mark_invalid record, attribute, forbidden_types
+        end
+      end
+
+      def mark_invalid(record, attribute, types)
+        record.errors.add attribute, :invalid, options.merge(:types => types.join(', '))
+      end
+
+      def allowed_types
+        [options[:content_type]].flatten.compact
+      end
+
+      def forbidden_types
+        [options[:not]].flatten.compact
       end
 
       def check_validity!
-        unless options.has_key?(:content_type)
-          raise ArgumentError, "You must pass in :content_type to the validator"
+        unless options.has_key?(:content_type) || options.has_key?(:not)
+          raise ArgumentError, "You must pass in either :content_type or :not to the validator"
         end
       end
     end
@@ -36,6 +56,7 @@ module Paperclip
       #   may not expect. For example, JPEG images are given image/pjpeg and
       #   PNGs are image/x-png, so keep that in mind when determining how you
       #   match.  Allows all by default.
+      # * +not+: Forbidden content types.
       # * +message+: The message to display when the uploaded file has an invalid
       #   content type.
       # * +if+: A lambda or name of an instance method. Validation will only

test/validators/attachment_content_type_validator_test.rb

@@ -76,6 +76,7 @@ class AttachmentContentTypeValidatorTest < Test::Unit::TestCase
     end
   end
 
+  context "whitelist format" do
     context "with an allowed type" do
       context "as a string" do
         setup do
@@ -167,6 +168,101 @@ class AttachmentContentTypeValidatorTest < Test::Unit::TestCase
         end
       end
     end
+  end
+
+  context "blacklist format" do
+    context "with an allowed type" do
+      context "as a string" do
+        setup do
+          build_validator :not => "image/gif"
+          @dummy.stubs(:avatar_content_type => "image/jpg")
+          @validator.validate(@dummy)
+        end
+
+        should "not set an error message" do
+          assert @dummy.errors[:avatar_content_type].blank?
+        end
+      end
+
+      context "as an regexp" do
+        setup do
+          build_validator :not => /^text\/.*/
+          @dummy.stubs(:avatar_content_type => "image/jpg")
+          @validator.validate(@dummy)
+        end
+
+        should "not set an error message" do
+          assert @dummy.errors[:avatar_content_type].blank?
+        end
+      end
+
+      context "as a list" do
+        setup do
+          build_validator :not => ["image/png", "image/jpg", "image/jpeg"]
+          @dummy.stubs(:avatar_content_type => "image/gif")
+          @validator.validate(@dummy)
+        end
+
+        should "not set an error message" do
+          assert @dummy.errors[:avatar_content_type].blank?
+        end
+      end
+    end
+
+    context "with a disallowed type" do
+      context "as a string" do
+        setup do
+          build_validator :not => "image/png"
+          @dummy.stubs(:avatar_content_type => "image/png")
+          @validator.validate(@dummy)
+        end
+
+        should "set a correct default error message" do
+          assert @dummy.errors[:avatar_content_type].present?
+          assert_includes @dummy.errors[:avatar_content_type], "is invalid"
+        end
+      end
+
+      context "as a regexp" do
+        setup do
+          build_validator :not => /^text\/.*/
+          @dummy.stubs(:avatar_content_type => "text/plain")
+          @validator.validate(@dummy)
+        end
+
+        should "set a correct default error message" do
+          assert @dummy.errors[:avatar_content_type].present?
+          assert_includes @dummy.errors[:avatar_content_type], "is invalid"
+        end
+      end
+
+      context "with :message option" do
+        context "without interpolation" do
+          setup do
+            build_validator :not => "image/png", :message => "should not be a PNG image"
+            @dummy.stubs(:avatar_content_type => "image/png")
+            @validator.validate(@dummy)
+          end
+
+          should "set a correct error message" do
+            assert_includes @dummy.errors[:avatar_content_type], "should not be a PNG image"
+          end
+        end
+
+        context "with interpolation" do
+          setup do
+            build_validator :not => "image/png", :message => "should not have content type %{types}"
+            @dummy.stubs(:avatar_content_type => "image/png")
+            @validator.validate(@dummy)
+          end
+
+          should "set a correct error message" do
+            assert_includes @dummy.errors[:avatar_content_type], "should not have content type image/png"
+          end
+        end
+      end
+    end
+  end
 
   context "using the helper" do
     setup do
@@ -185,8 +281,12 @@ class AttachmentContentTypeValidatorTest < Test::Unit::TestCase
       end
     end
 
-    should "not raise arguemnt error if :content_type was given" do
+    should "not raise argument error if :content_type was given" do
       build_validator :content_type => "image/jpg"
     end
+
+    should "not raise argument error if :not was given" do
+      build_validator :not => "image/jpg"
+    end
   end
 end