Force ransack gem version to fix undefined method 'polymorphic?'

Gemfile

@@ -11,6 +11,11 @@ gem "puma", "~> 3.0"
 gem "uglifier", ">= 1.3.0"
 gem 'figaro', '>= 1.1.1'
 
+# Force gem version to fix:
+# undefined method `polymorphic?' for ActiveRecord::Reflection::PolymorphicReflection
+# See: https://github.com/activerecord-hackery/ransack/issues/1039
+gem 'ransack', '2.1.1'
+
 gem 'delayed_job_active_record'
 gem "daemons"
 gem 'whenever', require: false

Gemfile.lock

@@ -527,8 +527,6 @@ GEM
     pg_search (2.3.0)
       activerecord (>= 4.2)
       activesupport (>= 4.2)
-    polyamorous (2.3.0)
-      activerecord (>= 5.0)
     powerpack (0.1.2)
     premailer (1.11.1)
       addressable
@@ -578,12 +576,11 @@ GEM
       thor (>= 0.19.0, < 2.0)
     rainbow (3.0.0)
     rake (12.3.3)
-    ransack (2.3.0)
+    ransack (2.1.1)
       actionpack (>= 5.0)
       activerecord (>= 5.0)
       activesupport (>= 5.0)
       i18n
-      polyamorous (= 2.3.0)
     rb-fsevent (0.10.3)
     rb-inotify (0.10.0)
       ffi (~> 1.0)
@@ -755,6 +752,7 @@ DEPENDENCIES
   letter_opener_web (~> 1.3.0)
   listen (~> 3.1.0)
   puma (~> 3.0)
+  ransack (= 2.1.1)
   sentry-raven
   spring
   spring-watcher-listen (~> 2.0.0)