Use IS [NOT] NULL instead of DBMS_LOB.COMPARE for nil CLOB/BLOB queries

lib/arel/visitors/oracle_common.rb

@@ -9,11 +9,14 @@ module OracleCommon
         # Fixes ORA-00932: inconsistent datatypes: expected - got CLOB
         def visit_Arel_Nodes_Equality(o, collector)
           left = o.left
+          right = o.right
+
+          return super if right.nil?
           return super unless %i(text binary).include?(cached_column_for(left)&.type)
 
           # https://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_lob.htm#i1016668
           # returns 0 when the comparison succeeds
-          comparator = Arel::Nodes::NamedFunction.new("DBMS_LOB.COMPARE", [left, o.right])
+          comparator = Arel::Nodes::NamedFunction.new("DBMS_LOB.COMPARE", [left, right])
           collector = visit comparator, collector
           collector << " = 0"
           collector

spec/active_record/oracle_enhanced/type/binary_spec.rb

@@ -15,13 +15,23 @@
     end
     class ::TestEmployee < ActiveRecord::Base
     end
+    class ::TestSerializedEmployee < ActiveRecord::Base
+      self.table_name = "test_employees"
+      serialize :binary_data, coder: YAML
+    end
+    class ::TestSerializedHashEmployee < ActiveRecord::Base
+      self.table_name = "test_employees"
+      serialize :binary_data, type: Hash, coder: YAML
+    end
     @binary_data = "\0\1\2\3\4\5\6\7\8\9" * 10000
     @binary_data2 = "\1\2\3\4\5\6\7\8\9\0" * 10000
   end
 
   after(:all) do
     @conn.drop_table :test_employees, if_exists: true
     Object.send(:remove_const, "TestEmployee")
+    Object.send(:remove_const, "TestSerializedEmployee")
+    Object.send(:remove_const, "TestSerializedHashEmployee")
   end
 
   after(:each) do
@@ -116,4 +126,32 @@ class ::TestEmployee < ActiveRecord::Base
     @employee.reload
     expect(@employee.binary_data).to eq(@binary_data)
   end
+
+  it "should find NULL BLOB data when queried with nil" do
+    TestEmployee.delete_all
+    TestEmployee.create!(binary_data: nil)
+    TestEmployee.create!(binary_data: @binary_data)
+    expect(TestEmployee.where(binary_data: nil)).to have_attributes(count: 1)
+  end
+
+  it "should find serialized NULL BLOB data when queried with nil" do
+    TestSerializedEmployee.delete_all
+    TestSerializedEmployee.create!(binary_data: nil)
+    TestSerializedEmployee.create!(binary_data: { data: "some data" })
+    expect(TestSerializedEmployee.where(binary_data: nil)).to have_attributes(count: 1)
+  end
+
+  it "should find serialized Hash NULL BLOB data when queried with nil" do
+    TestSerializedHashEmployee.delete_all
+    TestSerializedHashEmployee.create!(binary_data: nil)
+    TestSerializedHashEmployee.create!(binary_data: { data: "some data" })
+    expect(TestSerializedHashEmployee.where(binary_data: nil)).to have_attributes(count: 1)
+  end
+
+  it "should find serialized Hash NULL BLOB data when queried with {}" do
+    TestSerializedHashEmployee.delete_all
+    TestSerializedHashEmployee.create!(binary_data: nil)
+    TestSerializedHashEmployee.create!(binary_data: { data: "some data" })
+    expect(TestSerializedHashEmployee.where(binary_data: {})).to have_attributes(count: 1)
+  end
 end

spec/active_record/oracle_enhanced/type/text_spec.rb

@@ -31,6 +31,10 @@ class ::TestEmployee < ActiveRecord::Base; end
     class ::Test2Employee < ActiveRecord::Base
       serialize :comments
     end
+    class ::TestSerializedHashEmployee < ActiveRecord::Base
+      self.table_name = "test_employees"
+      serialize :comments, type: Hash, coder: YAML
+    end
     class ::TestEmployeeReadOnlyClob < ActiveRecord::Base
       self.table_name = "test_employees"
       attr_readonly :comments
@@ -47,6 +51,7 @@ class ::TestSerializeEmployee < ActiveRecord::Base
     @conn.drop_table :test_serialize_employees, if_exists: true
     Object.send(:remove_const, "TestEmployee")
     Object.send(:remove_const, "Test2Employee")
+    Object.send(:remove_const, "TestSerializedHashEmployee")
     Object.send(:remove_const, "TestEmployeeReadOnlyClob")
     Object.send(:remove_const, "TestSerializeEmployee")
     ActiveRecord::Base.clear_cache!
@@ -241,4 +246,32 @@ class ::TestSerializeEmployee < ActiveRecord::Base
     )
     expect(Test2Employee.where(comments: search_data)).to have_attributes(count: 1)
   end
+
+  it "should find NULL CLOB data when queried with nil" do
+    TestEmployee.delete_all
+    TestEmployee.create!(comments: nil)
+    TestEmployee.create!(comments: @char_data)
+    expect(TestEmployee.where(comments: nil)).to have_attributes(count: 1)
+  end
+
+  it "should find serialized NULL CLOB data when queried with nil" do
+    TestSerializeEmployee.delete_all
+    TestSerializeEmployee.create!(comments: nil)
+    TestSerializeEmployee.create!(comments: { some: "text" })
+    expect(TestSerializeEmployee.where(comments: nil)).to have_attributes(count: 1)
+  end
+
+  it "should find serialized Hash NULL CLOB data when queried with nil" do
+    TestSerializedHashEmployee.delete_all
+    TestSerializedHashEmployee.create!(comments: nil)
+    TestSerializedHashEmployee.create!(comments: { some: "text" })
+    expect(TestSerializedHashEmployee.where(comments: nil)).to have_attributes(count: 1)
+  end
+
+  it "should find serialized Hash NULL CLOB data when queried with {}" do
+    TestSerializedHashEmployee.delete_all
+    TestSerializedHashEmployee.create!(comments: nil)
+    TestSerializedHashEmployee.create!(comments: { some: "text" })
+    expect(TestSerializedHashEmployee.where(comments: {})).to have_attributes(count: 1)
+  end
 end