fk: :primary_key option for non-standard pk's.

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -647,9 +647,11 @@ module ActiveRecord
       end
 
       def add_foreign_key(from_table, to_table, options = {})
+        primary_key = options.fetch(:primary_key, "id")
+
         options = {
           column: options.fetch(:column),
-          primary_key: "id",
+          primary_key: primary_key,
           name: foreign_key_name(from_table, options)
         }
         at = create_alter_table from_table

activerecord/test/cases/migration/foreign_key_test.rb

@@ -1,9 +1,12 @@
 require 'cases/helper'
+require 'support/ddl_helper'
 
 if ActiveRecord::Base.connection.supports_foreign_keys?
 module ActiveRecord
   class Migration
     class ForeignKeyTest < ActiveRecord::TestCase
+      include DdlHelper
+
       class Rocket < ActiveRecord::Base
       end
 
@@ -55,6 +58,23 @@ module ActiveRecord
         assert_equal "astronauts_rocket_id_fk", fk.name
       end
 
+      def test_add_foreign_key_with_non_standard_primary_key
+        with_example_table @connection, "space_shuttles", "pk integer PRIMARY KEY" do
+          @connection.add_foreign_key(:astronauts, :space_shuttles,
+                                      column: "rocket_id", primary_key: "pk", name: "custom_pk")
+
+          foreign_keys = @connection.foreign_keys("astronauts")
+          assert_equal 1, foreign_keys.size
+
+          fk = foreign_keys.first
+          assert_equal "astronauts", fk.from_table
+          assert_equal "space_shuttles", fk.to_table
+          assert_equal "pk", fk.primary_key
+
+          @connection.remove_foreign_key :astronauts, name: "custom_pk"
+        end
+      end
+
       def test_remove_foreign_key
         @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id"
 

activerecord/test/support/ddl_helper.rb

@@ -1,8 +1,8 @@
 module DdlHelper
   def with_example_table(connection, table_name, definition = nil)
-    connection.exec_query("CREATE TABLE #{table_name}(#{definition})")
+    connection.execute("CREATE TABLE #{table_name}(#{definition})")
     yield
   ensure
-    connection.exec_query("DROP TABLE #{table_name}")
+    connection.execute("DROP TABLE #{table_name}")
   end
 end