IntegrityError when adding null value to foreign key using web2py

I am receiving an IntegrityError from web2py when trying to insert a record into a table named Foods. The table has a foreign key to Recipes, but I would like to add a row without a recipe_id.

<class 'gluon.contrib.pymysql.err.IntegrityError'>((1452, u'Cannot add or update a child row: a foreign key constraint fails (`pymeals`.`foods`, CONSTRAINT `foods_ibfk_1` FOREIGN KEY (`recipe_id`) REFERENCES `recipes` (`id`) ON DELETE CASCADE)'))

This is my table

+-----------+--------------+------+-----+---------+----------------+
| Field     | Type         | Null | Key | Default | Extra          |
+-----------+--------------+------+-----+---------+----------------+
| id        | int(11)      | NO   | PRI | NULL    | auto_increment |
| name      | varchar(255) | YES  |     | NULL    |                |
| recipe_id | int(11)      | YES  | MUL | NULL    |开发者_运维技巧                |
+-----------+--------------+------+-----+---------+----------------+

I have defined the table in web2py using the following code:

db.define_table('foods',
                Field('name'),
                Field('recipe_id', db.recipes, required=False, notnull=False, requires=None))

I believe the problem I am having lies with web2py as I can insert into the Foods table directly from the mysql command line prompt without specifying a recipe_id.

Am I missing something here? I'm new to MySQL and web2py :(

Make sure your Foods and Recipes have same engines. If you have different engines, then this problem will be occured.

Eg: Foods (MyISAM) and Recipes (InnoDB) will give error.