fix: allow functions to be default values

acceptance/cases/models/default_value_test.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require "test_helper"
+require "test_helpers/with_separate_database"
+
+module Models
+  class DefaultValueTest < SpannerAdapter::TestCase
+    include TestHelpers::WithSeparateDatabase
+
+    class DynamicItem < ActiveRecord::Base; end
+
+    def test_dynamic_default_values
+      connection.create_table :dynamic_items do |t|
+        t.column :col_timestamp, :datetime, default: -> { "CURRENT_TIMESTAMP()" }
+      end
+
+      item = DynamicItem.create!
+      item.reload
+      assert(item.col_timestamp)
+    end
+  end
+end

lib/activerecord_spanner_adapter/information_schema.rb

@@ -79,6 +79,14 @@ def table_columns table_name, column_name: nil
         column_name = row["COLUMN_NAME"]
         options = column_options[column_name]
 
+        default = row["COLUMN_DEFAULT"]
+        default_function = row["GENERATION_EXPRESSION"]
+
+        if /\w+\(.*\)/.match?(default)
+          default_function ||= default
+          default = nil
+        end
+
         Table::Column.new \
           table_name,
           column_name,
@@ -87,8 +95,8 @@ def table_columns table_name, column_name: nil
           allow_commit_timestamp: options["allow_commit_timestamp"],
           ordinal_position: row["ORDINAL_POSITION"],
           nullable: row["IS_NULLABLE"] == "YES",
-          default: row["COLUMN_DEFAULT"],
-          default_function: row["GENERATION_EXPRESSION"],
+          default: default,
+          default_function: default_function,
           generated: row["GENERATION_EXPRESSION"].present?
       end
     end