Handle invalid query IN() generated when a blank array is supplied in hash conditions

2 files changed, 7 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation/predicate_builder.rb b/activerecord/lib/active_record/relation/predicate_builder.rb
index 03f194c462..9e855209f9 100644
--- a/activerecord/lib/active_record/relation/predicate_builder.rb
+++ b/activerecord/lib/active_record/relation/predicate_builder.rb
@@ -24,7 +24,8 @@ module ActiveRecord
 
           case value
           when Array, ActiveRecord::Associations::AssociationCollection, ActiveRecord::NamedScope::Scope
-            attribute.in(value.to_a)
+            values = value.to_a
+            values.any? ? attribute.in(values) : attribute.eq(nil)
           when Range
             # TODO : Arel should handle ranges with excluded end.
             if value.exclude_end?
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index e31d0ee3e8..d34c9b4895 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -339,6 +339,11 @@ class RelationTest < ActiveRecord::TestCase
     assert_raises(ActiveRecord::RecordNotFound) { authors.find(['42', 43]) }
   end
 
+  def test_find_in_empty_array
+    authors = Author.scoped.where(:id => [])
+    assert authors.all.blank?
+  end
+
   def test_exists
     davids = Author.where(:name => 'David')
     assert davids.exists?