prevents removing submissions on user delete

The old foreign key was set to cascade, deleting the entire submission
when a user got deleted. This feels conceptually wrong since a
submission is connected to a team and not to a user. The user of the
team of the submission is more 'metadata' than anything else.

Author: tuupke

webapp/migrations/Version20240825115643.php

@@ -23,6 +23,8 @@ public function up(Schema $schema): void
     {
         $this->dropKeys();
         $this->addKeys(true);
+
+        $this->addSql('ALTER TABLE submission ADD CONSTRAINT FK_DB055AF3F132696E FOREIGN KEY (userid) REFERENCES user (userid) ON DELETE SET NULL');
     }
 
     public function down(Schema $schema): void
@@ -31,6 +33,8 @@ public function down(Schema $schema): void
 
         // Reinstate the 'restrict' keys.
         $this->addKeys(false);
+
+        $this->addSql('ALTER TABLE submission ADD CONSTRAINT FK_DB055AF3F132696E FOREIGN KEY (userid) REFERENCES user (userid) ON DELETE CASCADE');
     }
 
     public function dropKeys(): void
@@ -41,6 +45,7 @@ public function dropKeys(): void
         $this->addSql('ALTER TABLE judging_run DROP CONSTRAINT FK_29A6E6E13CBA64F2');
         $this->addSql('ALTER TABLE judging_run DROP CONSTRAINT judging_run_ibfk_1');
         $this->addSql('ALTER TABLE judgetask DROP CONSTRAINT judgetask_ibfk_1');
+        $this->addSql('ALTER TABLE submission DROP FOREIGN KEY FK_DB055AF3F132696E');
     }
 
     public function addKeys(bool $suffix): void

webapp/src/Entity/Submission.php

@@ -118,7 +118,7 @@ class Submission extends BaseApiEntity implements
     private Team $team;
 
     #[ORM\ManyToOne(inversedBy: 'submissions')]
-    #[ORM\JoinColumn(name: 'userid', referencedColumnName: 'userid', onDelete: 'CASCADE')]
+    #[ORM\JoinColumn(name: 'userid', referencedColumnName: 'userid', onDelete: 'SET NULL')]
     #[Serializer\Exclude]
     private ?User $user = null;