Extract `PredicateBuilder::CaseSensitiveHandler`

Currently uniqueness validator is coupled with building Arel ASTs.
This commit extracts `PredicateBuilder::CaseSensitiveHandler` for
decouple the building Arel ASTs.

1 files changed, 21 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/relation/predicate_builder/case_sensitive_handler.rb b/activerecord/lib/active_record/relation/predicate_builder/case_sensitive_handler.rb
new file mode 100644
index 0000000000..acf0bbd829
--- /dev/null
+++ b/activerecord/lib/active_record/relation/predicate_builder/case_sensitive_handler.rb
@@ -0,0 +1,21 @@
+module ActiveRecord
+  class PredicateBuilder
+    class CaseSensitiveHandler # :nodoc:
+      def call(attribute, value)
+        value.call(attribute)
+      end
+
+      class Value < Struct.new(:value, :table, :case_sensitive?) # :nodoc:
+        def call(attribute)
+          klass = table.send(:klass)
+          column = klass.column_for_attribute(attribute.name)
+          if case_sensitive?
+            klass.connection.case_sensitive_comparison(attribute, column, value)
+          else
+            klass.connection.case_insensitive_comparison(attribute, column, value)
+          end
+        end
+      end
+    end
+  end
+end