fk: support dependent option (:delete, :nullify and :restrict).

1 files changed, 13 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 6ba226765c..9610296043 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -524,7 +524,19 @@ module ActiveRecord
         create_table_info = select_one("SHOW CREATE TABLE #{quote_table_name(table_name)}")["Create Table"]
 
         fk_info.map do |row|
-          options = {column: row['column'], name: row['name'], primary_key: row['primary_key']}
+          options = {
+            column: row['column'],
+            name: row['name'],
+            primary_key: row['primary_key']
+          }
+
+          if create_table_info =~ /CONSTRAINT #{quote_column_name(row['name'])} FOREIGN KEY .* REFERENCES .* ON DELETE (CASCADE|SET NULL|RESTRICT)/
+            options[:dependent] = case $1
+              when 'CASCADE'  then :delete
+              when 'SET NULL' then :nullify
+              end
+          end
+
           ForeignKeyDefinition.new(table_name, row['to_table'], options)
         end
       end