Created migration fixing cascade delete on visits table

data/migrations/Version20180915110857.php

@@ -0,0 +1,50 @@
+<?php
+declare(strict_types=1);
+
+namespace ShlinkMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\DBAL\Schema\SchemaException;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20180915110857 extends AbstractMigration
+{
+    private const ON_DELETE_MAP = [
+        'visit_locations' => 'SET NULL',
+        'short_urls' => 'CASCADE',
+    ];
+
+    /**
+     * @param Schema $schema
+     * @throws SchemaException
+     */
+    public function up(Schema $schema): void
+    {
+        $visits = $schema->getTable('visits');
+        $foreignKeys = $visits->getForeignKeys();
+
+        // Remove all existing foreign keys and add them again with CASCADE delete
+        foreach ($foreignKeys as $foreignKey) {
+            $visits->removeForeignKey($foreignKey->getName());
+            $foreignTable = $foreignKey->getForeignTableName();
+
+            $visits->addForeignKeyConstraint(
+                $foreignTable,
+                $foreignKey->getLocalColumns(),
+                $foreignKey->getForeignColumns(),
+                [
+                    'onDelete' => self::ON_DELETE_MAP[$foreignTable],
+                    'onUpdate' => 'RESTRICT',
+                ]
+            );
+        }
+    }
+
+    public function down(Schema $schema): void
+    {
+        // Nothing to run
+    }
+}