Error 500 when updating discount

[geantas]

Describe the bug When updating a discount through an API, it throws an error related to SQL:

"SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`homestead`.`discount_reward_products`, CONSTRAINT `discount_reward_products_discount_reward_id_foreign` FOREIGN KEY (`discount_reward_id`) REFERENCES `discount_rewards` (`id`)) (SQL: delete from `discount_rewards` where `discount_rewards`.`discount_id` = 5 and `discount_rewards`.`discount_id` is not null)"

To Reproduce

1. Create a discount, fx:

   this.$getcandy.on('discounts', 'postDiscounts',
   {
    name: {
      en: 'Buy one get none free',
      da: 'Buy one get none free'
    },
    start_at: '2019-06-04T14:27:02.000Z',
    end_at: '2019-06-04T14:27:02.000Z'
   })

2. Get status 201
3. Get the discount ID from server response (fx. wz6d39dj).
4. Update discount, fx:

   this.$getcandy.on('discounts', 'putDiscountsDiscountId', 'wz6d39dj', {
   start_at: '2019-08-24T14:15:22Z',
   end_at: '2022-08-24T14:15:22Z',
   priority: 0,
   stop_rules: true,
   status: true,
   attribute_data: {
     name: {
       webstore: {
         da: 'Buy one get none free',
         en: 'Buy one get none free'
       }
     }
   },
   channels: {
     data: {
       id: 1,
       published_at: '2021-06-14T14:15:22Z'
     }
   },
   rewards: {
     data: {
       products: [
         {
           product_id: 24202,
           quantity: 1
         }
       ]
     }
   },
   sets: {
     data: [
       {
         scope: 'string',
         outcome: true,
         items: {
           data: [
             {
               eligibles: [
                 'string'
               ],
               type: 'string'
             }
           ]
         }
       }
     ]
   }
   })

5. See error in the server response.

Expected behavior Server returns a response with status 200.

[johshej]

Is the table definition missing an "ON DELETE CASCADE" for the "discount_reward_products_discount_reward_id_foreign" foreign key?

CREATE TABLE `discount_reward_products` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `product_id` int unsigned NOT NULL,
  `discount_reward_id` int unsigned NOT NULL,
  `quantity` int NOT NULL DEFAULT '1',
  `created_at` timestamp NULL DEFAULT NULL,
  `updated_at` timestamp NULL DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `discount_reward_products_discount_reward_id_foreign` (`discount_reward_id`),
  KEY `discount_reward_products_product_id_foreign` (`product_id`),
  CONSTRAINT `discount_reward_products_discount_reward_id_foreign` FOREIGN KEY (`discount_reward_id`) REFERENCES `discount_rewards` (`id`),
  CONSTRAINT `discount_reward_products_product_id_foreign` FOREIGN KEY (`product_id`) REFERENCES `products` (`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci