Foregin keys on MySQL

Describe the bug Foreign key constraints are not working on MySQL/MariaDB

To Reproduce

models/countries.py:

class Countries(Model):
    id = IntField(pk=True)
    code = CharField(max_length=2, unique=True, description="ISO 3166-1")
    name = CharField(max_length=50, index=True)

models/users.py:

class Users(Model):
    id = BigIntField(pk=True)
    firstname = CharField(max_length=128)
    lastname = CharField(max_length=128)

    country = ForeignKeyField(model_name="models.Countries")

Expected behavior Foreign keys should be created.

Additional context

The created SQL is like this:

CREATE TABLE `countries` (
    `id` INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
    `code` VARCHAR(2) NOT NULL UNIQUE COMMENT 'ISO 3166-1',
    `name` VARCHAR(50) NOT NULL,
    KEY `countries_name_991101_idx` (`name`)
) CHARACTER SET utf8mb4;

CREATE TABLE `users` (
    `id` BIGINT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
    `firstname` VARCHAR(128) NOT NULL,
    `lastname` VARCHAR(128) NOT NULL,
    `country_id` INT NOT NULL REFERENCES `countries` (`id`) ON DELETE CASCADE
) CHARACTER SET utf8mb4;

1st problem is that pk fields are unsigned, but ForeignKeyFields are not. When I tried to add a foreign key by SQL from a mysql gui, I got the following error: “Foreign key constraint is incorrectly formed” More info: https://stackoverflow.com/questions/8434518/mysql-foreign-key-constraint-is-incorrectly-formed-error

The 2nd is it seems MySQL can’t handle the REFERENCES in the same row as the field (it just ignores it), but it needs a separate FOREIGN KEY row inside CREATE TABLE.

[wallneradam]

Thanks, it works.

[grigi]

Makes sense, as a FK is a constraint on an index. We should just use the index naming system, but also for FK’s.