Merge pull request #47810 from Shopify/pm/fixture-id

Generate unique members of a composite key in fixtures

activerecord/lib/active_record/fixture_set/table_row.rb

@@ -87,7 +87,7 @@ def fill_row_model_attributes
           return unless model_class
           fill_timestamps
           interpolate_label
-          generate_primary_key
+          model_class.composite_primary_key? ? generate_composite_primary_key : generate_primary_key
           resolve_enums
           resolve_sti_reflections
         end
@@ -117,14 +117,28 @@ def interpolate_label
         end
 
         def generate_primary_key
-          # generate a primary key if necessary
-          Array(model_metadata.primary_key_name).each do |pk|
-            next if !model_metadata.has_column?(pk) || @row.include?(pk)
+          pk = model_metadata.primary_key_name
 
+          unless column_defined?(pk)
             @row[pk] = ActiveRecord::FixtureSet.identify(@label, model_metadata.column_type(pk))
           end
         end
 
+        def generate_composite_primary_key
+          id = ActiveRecord::FixtureSet.identify(@label)
+          model_metadata.primary_key_name.each_with_index do |column, index|
+            next if column_defined?(column)
+            raise "Automatic key generation assumes columns of type Integer." unless model_metadata.column_type(column) == :integer
+
+            # Shift label identifier index-#-of-times to differentiate sub-components in deterministic manner.
+            @row[column] = (id << index) % ActiveRecord::FixtureSet::MAX_ID
+          end
+        end
+
+        def column_defined?(col)
+          !model_metadata.has_column?(col) || @row.include?(col)
+        end
+
         def resolve_enums
           reflection_class.defined_enums.each do |name, values|
             if @row.include?(name)

activerecord/test/cases/fixtures_test.rb

@@ -1643,13 +1643,26 @@ def readonly_config
   end
 
   class CompositePkFixturesTest < ActiveRecord::TestCase
-    fixtures :cpk_orders, :cpk_books
+    fixtures :cpk_orders, :cpk_books, :authors
+
+    def test_generates_composite_primary_key_for_partially_filled_fixtures
+      david = authors(:david)
+      david_cpk_book = cpk_books(:cpk_known_author_david_book)
+
+      assert_not_empty(david_cpk_book.id.compact)
+      assert_equal david.id, david_cpk_book.author_id
+      assert_not_nil david_cpk_book.number
+    end
 
     def test_generates_composite_primary_key_ids
       assert_not_empty(cpk_orders(:cpk_groceries_order_1).id.compact)
 
       assert_not_nil(cpk_books(:cpk_great_author_first_book).author_id)
       assert_not_nil(cpk_books(:cpk_great_author_first_book).number)
     end
+
+    def test_generates_composite_primary_key_with_unique_components
+      assert_equal 2, cpk_orders(:cpk_groceries_order_1).id.uniq.size
+    end
   end
 end

activerecord/test/fixtures/cpk_books.yml

@@ -12,3 +12,8 @@ cpk_great_author_second_book:
 cpk_famous_author_first_book:
   title: "Ruby on Rails"
   revision: 1
+
+cpk_known_author_david_book:
+  author_id: 1
+  title: "David's CPK Book"
+  revision: 1