SQLite: Foreign Key Support

https://www.sqlite.org/foreignkeys.html

6 files changed, 81 insertions, 30 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
index 322684672f..807df2184a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb
@@ -15,9 +15,9 @@ module ActiveRecord
         end
 
         delegate :quote_column_name, :quote_table_name, :quote_default_expression, :type_to_sql,
-          :options_include_default?, :supports_indexes_in_create?, :supports_foreign_keys?, :foreign_key_options, to: :@conn
+          :options_include_default?, :supports_indexes_in_create?, :supports_foreign_keys_in_create?, :foreign_key_options, to: :@conn
         private :quote_column_name, :quote_table_name, :quote_default_expression, :type_to_sql,
-          :options_include_default?, :supports_indexes_in_create?, :supports_foreign_keys?, :foreign_key_options
+          :options_include_default?, :supports_indexes_in_create?, :supports_foreign_keys_in_create?, :foreign_key_options
 
         private
 
@@ -49,7 +49,7 @@ module ActiveRecord
               statements.concat(o.indexes.map { |column_name, options| index_in_create(o.name, column_name, options) })
             end
 
-            if supports_foreign_keys?
+            if supports_foreign_keys_in_create?
               statements.concat(o.foreign_keys.map { |to_table, options| foreign_key_in_create(o.name, to_table, options) })
             end
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index cf2269bf12..348396de72 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -310,6 +310,12 @@ module ActiveRecord
         false
       end
 
+      # Does this adapter support creating foreign key constraints
+      # in the same statement as creating the table?
+      def supports_foreign_keys_in_create?
+        supports_foreign_keys?
+      end
+
       # Does this adapter support views?
       def supports_views?
         false
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 2e3419991e..ca6de37a6b 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -130,6 +130,10 @@ module ActiveRecord
         true
       end
 
+      def supports_foreign_keys_in_create?
+        sqlite_version >= "3.6.19"
+      end
+
       def supports_views?
         true
       end
@@ -439,6 +443,19 @@ module ActiveRecord
         rename_column_indexes(table_name, column.name, new_column_name)
       end
 
+      def foreign_keys(table_name)
+        fk_info = select_all("PRAGMA foreign_key_list(#{quote(table_name)})", "SCHEMA")
+        fk_info.map do |row|
+          options = {
+            column: row["from"],
+            primary_key: row["to"],
+            on_delete: extract_foreign_key_action(row["on_delete"]),
+            on_update: extract_foreign_key_action(row["on_update"])
+          }
+          ForeignKeyDefinition.new(table_name, row["table"], options)
+        end
+      end
+
       private
 
         def table_structure(table_name)
@@ -592,6 +609,14 @@ module ActiveRecord
           SQLite3::TableDefinition.new(*args)
         end
 
+        def extract_foreign_key_action(specifier)
+          case specifier
+          when "CASCADE"; :cascade
+          when "SET NULL"; :nullify
+          when "RESTRICT"; :restrict
+          end
+        end
+
         def configure_connection
           execute("PRAGMA foreign_keys = ON", "SCHEMA")
         end
diff --git a/activerecord/test/cases/migration/foreign_key_test.rb b/activerecord/test/cases/migration/foreign_key_test.rb
index 9be6667aa1..96e775a58b 100644
--- a/activerecord/test/cases/migration/foreign_key_test.rb
+++ b/activerecord/test/cases/migration/foreign_key_test.rb
@@ -2,6 +2,26 @@ require "cases/helper"
 require "support/ddl_helper"
 require "support/schema_dumping_helper"
 
+if ActiveRecord::Base.connection.supports_foreign_keys_in_create?
+  module ActiveRecord
+    class Migration
+      class ForeignKeyInCreateTest < ActiveRecord::TestCase
+        def test_foreign_keys
+          foreign_keys = ActiveRecord::Base.connection.foreign_keys("fk_test_has_fk")
+          assert_equal 1, foreign_keys.size
+
+          fk = foreign_keys.first
+          assert_equal "fk_test_has_fk", fk.from_table
+          assert_equal "fk_test_has_pk", fk.to_table
+          assert_equal "fk_id", fk.column
+          assert_equal "pk_id", fk.primary_key
+          assert_equal "fk_name", fk.name unless current_adapter?(:SQLite3Adapter)
+        end
+      end
+    end
+  end
+end
+
 if ActiveRecord::Base.connection.supports_foreign_keys?
   module ActiveRecord
     class Migration
@@ -29,10 +49,8 @@ if ActiveRecord::Base.connection.supports_foreign_keys?
         end
 
         teardown do
-          if defined?(@connection)
-            @connection.drop_table "astronauts", if_exists: true
-            @connection.drop_table "rockets", if_exists: true
-          end
+          @connection.drop_table "astronauts", if_exists: true
+          @connection.drop_table "rockets", if_exists: true
         end
 
         def test_foreign_keys
@@ -305,9 +323,11 @@ else
           @connection.remove_foreign_key :clubs, :categories
         end
 
-        def test_foreign_keys_should_raise_not_implemented
-          assert_raises NotImplementedError do
-            @connection.foreign_keys("clubs")
+        unless current_adapter?(:SQLite3Adapter)
+          def test_foreign_keys_should_raise_not_implemented
+            assert_raises NotImplementedError do
+              @connection.foreign_keys("clubs")
+            end
           end
         end
       end
diff --git a/activerecord/test/cases/migration/references_foreign_key_test.rb b/activerecord/test/cases/migration/references_foreign_key_test.rb
index 4957ab8b3d..560adcbfed 100644
--- a/activerecord/test/cases/migration/references_foreign_key_test.rb
+++ b/activerecord/test/cases/migration/references_foreign_key_test.rb
@@ -1,9 +1,9 @@
 require "cases/helper"
 
-if ActiveRecord::Base.connection.supports_foreign_keys?
+if ActiveRecord::Base.connection.supports_foreign_keys_in_create?
   module ActiveRecord
     class Migration
-      class ReferencesForeignKeyTest < ActiveRecord::TestCase
+      class ReferencesForeignKeyInCreateTest < ActiveRecord::TestCase
         setup do
           @connection = ActiveRecord::Base.connection
           @connection.create_table(:testing_parents, force: true)
@@ -61,6 +61,24 @@ if ActiveRecord::Base.connection.supports_foreign_keys?
           assert_equal([["testings", "testing_parents", "parent_id"]],
                        fks.map { |fk| [fk.from_table, fk.to_table, fk.column] })
         end
+      end
+    end
+  end
+end
+
+if ActiveRecord::Base.connection.supports_foreign_keys?
+  module ActiveRecord
+    class Migration
+      class ReferencesForeignKeyTest < ActiveRecord::TestCase
+        setup do
+          @connection = ActiveRecord::Base.connection
+          @connection.create_table(:testing_parents, force: true)
+        end
+
+        teardown do
+          @connection.drop_table "testings", if_exists: true
+          @connection.drop_table "testing_parents", if_exists: true
+        end
 
         test "foreign keys cannot be added to polymorphic relations when creating the table" do
           @connection.create_table :testings do |t|
diff --git a/activerecord/test/schema/sqlite_specific_schema.rb b/activerecord/test/schema/sqlite_specific_schema.rb
deleted file mode 100644
index cc7c36fe2b..0000000000
--- a/activerecord/test/schema/sqlite_specific_schema.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-ActiveRecord::Schema.define do
-  execute "DROP TABLE fk_test_has_fk" rescue nil
-  execute "DROP TABLE fk_test_has_pk" rescue nil
-  execute <<_SQL
-  CREATE TABLE 'fk_test_has_pk' (
-    'pk_id' INTEGER NOT NULL PRIMARY KEY
-  );
-_SQL
-
-  execute <<_SQL
-  CREATE TABLE 'fk_test_has_fk' (
-    'id'    INTEGER NOT NULL PRIMARY KEY,
-    'fk_id' INTEGER NOT NULL,
-
-    FOREIGN KEY ('fk_id') REFERENCES 'fk_test_has_pk'('pk_id')
-  );
-_SQL
-end