Fix a bug affecting validations of enum attributes

This fixes a bug where any enum attribute of a model
would be evaluated always as 0 when calling the
database on validations.

This fix converts the value of the enum attribute
to its integer value rather than the string before
building the relation as the bug occured when the
string finally gets converted to integer using
string.to_i which converts it to 0.

[Vilius Luneckas, Ahmed AbouElhamayed]

3 files changed, 42 insertions, 0 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 58f680a03f..2845e945db 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,11 @@
+*   Fixed error with validation with enum fields for records where the
+    value for any enum attribute is always evaluated as 0 during
+    uniqueness validation.
+
+    Fixes #14172
+
+    *Vilius Luneckas* *Ahmed AbouElhamayed*
+
 * `before_add` callbacks are fired before the record is saved on
   `has_and_belongs_to_many` assocations *and* on `has_many :through`
   associations.  Before this change, `before_add` callbacks would be fired
diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index 7ebe9dfec0..49b0f73219 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -13,6 +13,7 @@ module ActiveRecord
       def validate_each(record, attribute, value)
         finder_class = find_finder_class_for(record)
         table = finder_class.arel_table
+        value = map_enum_attribute(finder_class,attribute,value)
         value = deserialize_attribute(record, attribute, value)
 
         relation = build_relation(finder_class, table, attribute, value)
@@ -91,6 +92,12 @@ module ActiveRecord
         value = coder.dump value if value && coder
         value
       end
+
+      def map_enum_attribute(klass,attribute,value)
+        mapping = klass.enum_mapping_for(attribute.to_s)
+        value = mapping[value] if value && mapping
+        value
+      end
     end
 
     module ClassMethods
diff --git a/activerecord/test/cases/enum_test.rb b/activerecord/test/cases/enum_test.rb
index 1b95708cb3..f8ebd7caee 100644
--- a/activerecord/test/cases/enum_test.rb
+++ b/activerecord/test/cases/enum_test.rb
@@ -222,4 +222,31 @@ class EnumTest < ActiveRecord::TestCase
       end
     end
   end
+
+  test "validate uniqueness" do
+    klass = Class.new(ActiveRecord::Base) do
+      def self.name; 'Book'; end
+      enum status: [:proposed, :written]
+      validates_uniqueness_of :status
+    end
+    klass.delete_all
+    klass.create!(status: "proposed")
+    book = klass.new(status: "written")
+    assert book.valid?
+    book.status = "proposed"
+    assert_not book.valid?
+  end
+
+  test "validate inclusion of value in array" do
+    klass = Class.new(ActiveRecord::Base) do
+      def self.name; 'Book'; end
+      enum status: [:proposed, :written]
+      validates_inclusion_of :status, in: ["written"]
+    end
+    klass.delete_all
+    invalid_book = klass.new(status: "proposed")
+    assert_not invalid_book.valid?
+    valid_book = klass.new(status: "written")
+    assert valid_book.valid?
+  end
 end