SQLite: Foreign Key Support

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

3 files changed, 34 insertions, 3 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