Laravel CRUD删除不适用于外键

Question

I have a foreign relationship with category_id column in database but while deleting i get error. This is my code for delete:

  public function destroy($id)
{
    $category = Category::find($id);
    $category->delete();
    Session::flash('success', 'The category was successfully deleted.');
    return redirect()->route('categories.index');
}

Error i seen is :

SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`fitilicious`.`products`, CONSTRAINT `products_category_id_foreign` FOREIGN KEY (`category_id`) REFERENCES `categories` (`id`)) (SQL: delete from `categories` where `id` = 2)

Please help.

Answer 1

My bet is on the foreign key being set to ON DELETE RESTRICT instead of CASCADE.

Cannot delete or update a parent row: a foreign key constraint fails ( fitilicious . products , CONSTRAINT products_category_id_foreign FOREIGN KEY ( category_id ) REFERENCES categories ( id )) (SQL: delete from categories where id = 2)

This tells us that there is a row in table "products" which is referencing the category you are attempting to delete.

• ON DELETE CASCADE will also delete the product.
• ON DELETE RESTRICT will prevent deletion of a non-empty category
• ON DELETE SET NULL will delete the category and set category_id to NULL in products table

Each has its uses, but you need to choose which one you need.