Rails：如何为以下逻辑建模

Question

I have a model called Item, which belongs to Report.

class Item < ApplicationRecord
 belongs_to :report
end

For my Item, I want to have an attribute called item_category(besides other attributes).

t.string "item_category"

I will have some standard categories that will have a tax associated with them.

My question is: Should I have another two models for Category and Tax, and load the available categories that will be created as options for my Item category attribute ? (or Tax should be an attribute for a Category model, or none of them)

After some time, another category can be added/removed, same for the Tax and I want this to be as modular as possible, not to make changes every time I want to remove/add category/tax. How should I approach it?

Answer 1

It really depends on how frequently categories will change. If tax + category pair is constant, then I would suggest adding that in code, as a constant (Hash, maybe, structured as { "category" : "tax" }). If taxes will change often, then it makes more sense of making another Category model and storing your tax + Category stuff there.

From your description it doesn't seem like you need a separate Tax model (I assume you will only have % amount there). This is based on an assumption that Category has only one tax.

That is all I can suggest with the information you have provided. But the most optimal methid laregly depends on more details description of your business logic

Answer 2

I suggest the model

• Model: Categorytax
  • category:string
  • taxProcent: integer