Laravel Eloquent - 一张表的多个模型

Question

I have 3 eloquent models which are pretty much te same and represent discounts:

• AbsoluteDiscount
• OneProductForFreeDiscount
• QuantityDiscount

They all will get a method called "canBeApplied(Productable $productable)". Which does have a look at the given productables and then determine if the productable will be eligible for the discount it represents. The implementation of this method is different for those 3 different Discounts.

Now, their attributes are pretty much the same. They all have these attributes: name, active, valid_from, valid_trough. So i think i would need to have one single database table with these fields / column to represent those 3 discount eloquent models:

• id
• name
• discountable_type
• active
• valid_from
• valid_until

The column discountable_type will then the the fully qualified class names of the discounts. In case of a 10 and 20 dollar gift card you would use the name "Gift card - 10 dollar" and "20 dollar" and both of them the discountable_type of "Namspace\For\AbsoluteDiscount\AbsoluteDiscount".

What i am thinking i am needing to do is:

• Create a base eloquent model for those discount models to extend.
• Override the where method in each discount, appending an additional where method call to it with this as its content ('discountable_type', '=', AbsoluteDiscount::class) before returning it.

But then we also have methods: get, first, all and maybe more that need to be overridden. And what about saving? And these steps need to be done for all 3 discount models. Is there an easy way to do it like this or is this something i must not do?

Answer 1

I think you can use this trait here: https://github.com/Nanigans/single-table-inheritance

However, it based on singleTableTypeField attribute, which doesn't allow to get a child by conditions, only by some kind of type_id column. But I think it would be not so difficult to modify it to fit your needs.

Answer 2

Well, this isn't a Polymorphic relation but looks a bit like it. A polymorphic relation specifies that a model belongs to one or more other models. This is different situation since these models don't belong to other models but are all alike. I don't know what a solution for this could be