Add adapter option disallowing foreign keys

Author: promulo

activerecord/CHANGELOG.md

@@ -1,3 +1,18 @@
+*   Add adapter option disallowing foreign keys
+
+    This adds a new option to be added to `database.yml` which enables skipping
+    foreign key constraints usage even if the underlying database supports them.
+
+    Usage:
+    ```yaml
+    development:
+        <<: *default
+        database: db/development.sqlite3
+        foreign_keys: false
+    ```
+
+    *Paulo Barros*
+
 *   Add configurable deprecation warning for singular associations
 
     This adds a deprecation warning when using the plural name of a singular associations in `where`.

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

@@ -14,9 +14,9 @@ def accept(o)
       end
 
       delegate :quote_column_name, :quote_table_name, :quote_default_expression, :type_to_sql,
-        :options_include_default?, :supports_indexes_in_create?, :supports_foreign_keys?,
-        :quoted_columns_for_index, :supports_partial_index?, :supports_check_constraints?, :supports_exclusion_constraints?,
-        to: :@conn, private: true
+        :options_include_default?, :supports_indexes_in_create?, :use_foreign_keys?,
+        :quoted_columns_for_index, :supports_partial_index?, :supports_check_constraints?,
+        :supports_exclusion_constraints?, to: :@conn, private: true
 
       private
         def visit_AlterTable(o)
@@ -51,7 +51,7 @@ def visit_TableDefinition(o)
             statements.concat(o.indexes.map { |column_name, options| index_in_create(o.name, column_name, options) })
           end
 
-          if supports_foreign_keys?
+          if use_foreign_keys?
             statements.concat(o.foreign_keys.map { |fk| accept fk })
           end
 

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

@@ -1074,7 +1074,7 @@ def foreign_keys(table_name)
       #   (PostgreSQL only) Specify whether or not the foreign key should be deferrable. Valid values are booleans or
       #   +:deferred+ or +:immediate+ to specify the default behavior. Defaults to +false+.
       def add_foreign_key(from_table, to_table, **options)
-        return unless supports_foreign_keys?
+        return unless use_foreign_keys?
         return if options[:if_not_exists] == true && foreign_key_exists?(from_table, to_table)
 
         options = foreign_key_options(from_table, to_table, options)
@@ -1115,7 +1115,7 @@ def add_foreign_key(from_table, to_table, **options)
       # [<tt>:to_table</tt>]
       #   The name of the table that contains the referenced primary key.
       def remove_foreign_key(from_table, to_table = nil, **options)
-        return unless supports_foreign_keys?
+        return unless use_foreign_keys?
         return if options.delete(:if_exists) == true && !foreign_key_exists?(from_table, to_table)
 
         fk_name_to_delete = foreign_key_for!(from_table, to_table: to_table, **options).name
@@ -1394,6 +1394,10 @@ def create_schema_dumper(options) # :nodoc:
         SchemaDumper.create(self, options)
       end
 
+      def use_foreign_keys?
+        supports_foreign_keys? && foreign_keys_enabled?
+      end
+
       private
         def validate_change_column_null_argument!(value)
           unless value == true || value == false
@@ -1548,7 +1552,7 @@ def foreign_key_name(table_name, options)
         end
 
         def foreign_key_for(from_table, **options)
-          return unless supports_foreign_keys?
+          return unless use_foreign_keys?
           foreign_keys(from_table).detect { |fk| fk.defined_for?(**options) }
         end
 
@@ -1565,6 +1569,10 @@ def extract_foreign_key_action(specifier)
           end
         end
 
+        def foreign_keys_enabled?
+          @config.fetch(:foreign_keys, true)
+        end
+
         def check_constraint_name(table_name, **options)
           options.fetch(:name) do
             expression = options.fetch(:expression)

activerecord/lib/active_record/schema_dumper.rb

@@ -116,7 +116,7 @@ def tables(stream)
         end
 
         # dump foreign keys at the end to make sure all dependent tables exist.
-        if @connection.supports_foreign_keys?
+        if @connection.use_foreign_keys?
           sorted_tables.each do |tbl|
             foreign_keys(tbl, stream) unless ignored?(tbl)
           end

activerecord/test/cases/migration/foreign_key_test.rb

@@ -554,6 +554,34 @@ def test_schema_dumping_with_defferable_initially_immediate
           end
         end
 
+        def test_does_not_create_foreign_keys_when_bypassed_by_config
+          connection = ActiveRecord::Base.establish_connection(
+            {
+              adapter: "sqlite3",
+              database: "test/db/test.sqlite3",
+              foreign_keys: false,
+            }
+          ).connection
+
+          connection.create_table "rockets", force: true do |t|
+            t.string :name
+          end
+          connection.create_table "astronauts", force: true do |t|
+            t.string :name
+            t.references :rocket
+          end
+
+          connection.add_foreign_key :astronauts, :rockets
+
+          foreign_keys = connection.foreign_keys("astronauts")
+          assert_equal 0, foreign_keys.size
+        ensure
+          connection.drop_table "astronauts", if_exists: true rescue nil
+          connection.drop_table "rockets", if_exists: true rescue nil
+
+          ActiveRecord::Base.establish_connection(:arunit)
+        end
+
         def test_schema_dumping
           @connection.add_foreign_key :astronauts, :rockets
           output = dump_table_schema "astronauts"

activerecord/test/cases/schema_dumper_test.rb

@@ -416,6 +416,21 @@ def test_do_not_dump_foreign_keys_for_ignored_tables
       output = dump_table_schema "authors"
       assert_equal ["authors"], output.scan(/^\s*add_foreign_key "([^"]+)".+$/).flatten
     end
+
+    def test_do_not_dump_foreign_keys_when_bypassed_by_config
+      ActiveRecord::Base.establish_connection(
+        {
+          adapter: "sqlite3",
+          database: "test/db/test.sqlite3",
+          foreign_keys: false,
+        }
+      )
+
+      output = perform_schema_dump
+      assert_no_match(/^\s+add_foreign_key "fk_test_has_fk"[^\n]+\n\s+add_foreign_key "lessons_students"/, output)
+    ensure
+      ActiveRecord::Base.establish_connection(:arunit)
+    end
   end
 
   class CreateDogMigration < ActiveRecord::Migration::Current