Add column names method

lib/active_hash/base.rb

@@ -50,6 +50,23 @@ def field_names
         @field_names ||= []
       end
 
+      #
+      # Useful for CSV integration needing column names as strings.
+      #
+      # @return [Array<String>] An array of column names as strings.
+      #
+      # @example Usage
+      #  class Country < ActiveHash::Base
+      #    fields :name, :code
+      #  end
+      #
+      #  Country.column_names
+      #  # => ["id", "name", "code"]
+      #
+      def column_names
+        field_names.map(&:name)
+      end
+
       def the_meta_class
         class << self
           self

spec/active_hash/base_spec.rb

@@ -116,6 +116,17 @@ class Country < ActiveHash::Base
     end
   end
 
+  describe ".column_names" do
+    before do
+      Country.fields :name, :iso_name, "size"
+    end
+
+    it "returns an array of column names" do
+      skip "Not supported in Ruby 3.0.0" if RUBY_VERSION < "3.0.0"
+      expect(Country.column_names).to eq(["name", "iso_name", "size"])
+    end
+  end
+
   describe ".data=" do
     before do
       class Region < ActiveHash::Base

spec/active_yaml/aliases_spec.rb

@@ -43,6 +43,12 @@ class KeyProduct < ActiveYaml::Base
         model.all
         expect(model.field_names).to match_array [:name, :flavor, :price]
       end
+
+      it 'excludes them from column_names' do
+        skip "Not supported in Ruby 3.0.0" if RUBY_VERSION < "3.0.0"
+        model.all
+        expect(model.column_names).to match_array ["name", "flavor", "price"]
+      end
     end
   end
 
@@ -70,6 +76,12 @@ class KeyProduct < ActiveYaml::Base
         model.all
         expect(model.field_names).to match_array [:name, :flavor, :price, :slogan, :key]
       end
+
+      it 'excludes them from column_names' do
+        skip "Not supported in Ruby 3.0.0" if RUBY_VERSION < "3.0.0"
+        model.all
+        expect(model.column_names).to match_array ["name", "flavor", "price", "slogan", "key"]
+      end
     end
   end