Fix CLOB/BLOB insertion when prepared_statements is false

When prepared_statements is disabled, INSERT statements use empty_clob()/
empty_blob() literals instead of bind parameters. The LOB module previously
only had after_update callbacks, causing LOB data to be lost on INSERT.

This commonly occurs in Rails 8 development environments where
config.active_record.query_log_tags_enabled = true (the default) causes
Rails to automatically disable prepared statements.

Changes:
- Add before_create :record_lobs_for_create callback
- Add after_create :enhanced_write_lobs callback
- Add record_lobs_for_create method to track non-nil LOB columns on create
- Skip callback when prepared_statements is enabled (LOB data already
  written via temporary LOB binding in type_cast())

Fixes rsim#2477 (CLOBs empty after creation)
Fixes rsim#2483 (redundant double-write with prepared statements)

Author: andynu

lib/active_record/connection_adapters/oracle_enhanced/lob.rb

@@ -11,6 +11,8 @@ module Lob # :nodoc:
 
           # After setting large objects to empty, select the OCI8::LOB
           # and write back the data.
+          before_create :record_lobs_for_create
+          after_create :enhanced_write_lobs
           before_update :record_changed_lobs
           after_update :enhanced_write_lobs
         end
@@ -25,11 +27,21 @@ def lob_columns
 
         private
           def enhanced_write_lobs
+            # Skip if using prepared statements - LOB data is already written via temp LOB binding
+            return if self.class.connection.prepared_statements
+
             if self.class.connection.is_a?(ConnectionAdapters::OracleEnhancedAdapter) &&
                 !(self.class.custom_create_method || self.class.custom_update_method)
               self.class.connection.write_lobs(self.class.table_name, self.class, attributes, @changed_lob_columns)
             end
           end
+
+          def record_lobs_for_create
+            @changed_lob_columns = self.class.lob_columns.select do |col|
+              !attributes[col.name].nil? && !self.class.readonly_attributes.to_a.include?(col.name)
+            end
+          end
+
           def record_changed_lobs
             @changed_lob_columns = self.class.lob_columns.select do |col|
               self.will_save_change_to_attribute?(col.name) && !self.class.readonly_attributes.to_a.include?(col.name)

spec/active_record/oracle_enhanced/type/text_spec.rb

@@ -241,4 +241,55 @@ class ::TestSerializeEmployee < ActiveRecord::Base
     )
     expect(Test2Employee.where(comments: search_data)).to have_attributes(count: 1)
   end
+
+  describe "with prepared_statements disabled" do
+    around(:each) do |example|
+      old_prepared_statements = @conn.prepared_statements
+      @conn.instance_variable_set(:@prepared_statements, false)
+      example.run
+      @conn.instance_variable_set(:@prepared_statements, old_prepared_statements)
+    end
+
+    it "should create record with CLOB data when prepared_statements is false" do
+      @employee = TestEmployee.create!(
+        first_name: "First",
+        last_name: "Last",
+        comments: @char_data
+      )
+      @employee.reload
+      expect(@employee.comments).to eq(@char_data)
+    end
+
+    it "should create record with short CLOB data when prepared_statements is false" do
+      short_data = "Short CLOB content"
+      @employee = TestEmployee.create!(
+        first_name: "First",
+        last_name: "Last",
+        comments: short_data
+      )
+      @employee.reload
+      expect(@employee.comments).to eq(short_data)
+    end
+
+    it "should create record with empty CLOB when prepared_statements is false" do
+      @employee = TestEmployee.create!(
+        first_name: "First",
+        last_name: "Last",
+        comments: ""
+      )
+      @employee.reload
+      expect(@employee.comments).to eq("")
+    end
+
+    it "should create record with serialized CLOB data when prepared_statements is false" do
+      ruby_data = { "test" => ["ruby", :data, 123] }
+      @employee = Test2Employee.create!(
+        first_name: "First",
+        last_name: "Last",
+        comments: ruby_data
+      )
+      @employee.reload
+      expect(@employee.comments).to eq(ruby_data)
+    end
+  end
 end