#30524: on_delete doesn't work properly with MySql.
-------------------------------+--------------------------------------
     Reporter:  dheeraj135     |                    Owner:  nobody
         Type:  Bug            |                   Status:  new
    Component:  Uncategorized  |                  Version:  2.2
     Severity:  Normal         |               Resolution:
     Keywords:  Foreign Key    |             Triage Stage:  Unreviewed
    Has patch:  0              |      Needs documentation:  0
  Needs tests:  0              |  Patch needs improvement:  0
Easy pickings:  0              |                    UI/UX:  0
-------------------------------+--------------------------------------
Changes (by dheeraj135):

 * keywords:  Foreign Key, indexes => Foreign Key


Old description:

> Model:
>
> {{{
> class Attempt(models.Model):
>     student = models.ForeignKey(Student, models.CASCADE,
> related_name='quiz_attempts',null=False)
>     quiz =
> models.ForeignKey(Quiz,on_delete=models.CASCADE,related_name='quiz_attempts')
>     score = models.FloatField()
>     over = models.BooleanField(default=False)
>     date = models.DateTimeField(auto_now_add=True)
>     currquestion =
> models.ForeignKey(Question,null=True,default=None,on_delete=models.SET_NULL)
>
>     class Meta:
>         indexes = [
>             models.Index(fields=['student']),
>             models.Index(fields=['quiz']),
>         ]
>
> }}}
> Table created in MySql:
>
> {{{
> CREATE TABLE `classroom_attempt` (
>   `id` int(11) NOT NULL AUTO_INCREMENT,
>   `score` double NOT NULL,
>   `over` tinyint(1) NOT NULL,
>   `date` datetime(6) NOT NULL,
>   `currquestion_id` int(11) DEFAULT NULL,
>   `quiz_id` int(11) NOT NULL,
>   `student_id` int(11) NOT NULL,
>   PRIMARY KEY (`id`),
>   KEY `classroom_a_student_1a21bc_idx` (`student_id`),
>   KEY `classroom_a_quiz_id_eef64a_idx` (`quiz_id`),
>   KEY `classroom_attempt_currquestion_id_545301ef_fk_classroom`
> (`currquestion_id`),
>   CONSTRAINT `classroom_attempt_currquestion_id_545301ef_fk_classroom`
> FOREIGN KEY (`currquestion_id`) REFERENCES `classroom_question` (`id`),
>   CONSTRAINT `classroom_attempt_quiz_id_e227b203_fk_classroom_quiz_id`
> FOREIGN KEY (`quiz_id`) REFERENCES `classroom_quiz` (`id`),
>   CONSTRAINT `classroom_attempt_student_id_a4dc81cd_fk_classroom` FOREIGN
> KEY (`student_id`) REFERENCES `classroom_student` (`user_id`)
> ) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
> +-------------------+---------------------
> }}}
>
> As you can notice, indexes and models.CASCADE is not applied.

New description:

 Model:

 {{{
 class Attempt(models.Model):
     student = models.ForeignKey(Student, models.CASCADE,
 related_name='quiz_attempts',null=False)
     quiz =
 models.ForeignKey(Quiz,on_delete=models.CASCADE,related_name='quiz_attempts')
     score = models.FloatField()
     over = models.BooleanField(default=False)
     date = models.DateTimeField(auto_now_add=True)
     currquestion =
 models.ForeignKey(Question,null=True,default=None,on_delete=models.SET_NULL)

     class Meta:
         indexes = [
             models.Index(fields=['student']),
             models.Index(fields=['quiz']),
         ]

 }}}
 Table created in MySql:

 {{{
 CREATE TABLE `classroom_attempt` (
   `id` int(11) NOT NULL AUTO_INCREMENT,
   `score` double NOT NULL,
   `over` tinyint(1) NOT NULL,
   `date` datetime(6) NOT NULL,
   `currquestion_id` int(11) DEFAULT NULL,
   `quiz_id` int(11) NOT NULL,
   `student_id` int(11) NOT NULL,
   PRIMARY KEY (`id`),
   KEY `classroom_a_student_1a21bc_idx` (`student_id`),
   KEY `classroom_a_quiz_id_eef64a_idx` (`quiz_id`),
   KEY `classroom_attempt_currquestion_id_545301ef_fk_classroom`
 (`currquestion_id`),
   CONSTRAINT `classroom_attempt_currquestion_id_545301ef_fk_classroom`
 FOREIGN KEY (`currquestion_id`) REFERENCES `classroom_question` (`id`),
   CONSTRAINT `classroom_attempt_quiz_id_e227b203_fk_classroom_quiz_id`
 FOREIGN KEY (`quiz_id`) REFERENCES `classroom_quiz` (`id`),
   CONSTRAINT `classroom_attempt_student_id_a4dc81cd_fk_classroom` FOREIGN
 KEY (`student_id`) REFERENCES `classroom_student` (`user_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
 +-------------------+---------------------
 }}}

 As you can notice models.CASCADE is not applied.

--

-- 
Ticket URL: <https://code.djangoproject.com/ticket/30524#comment:1>
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