What is the difference between using `:references` and `:belongs_to` in a generate command in Rails?

pillaiindu · 13 June 2024 11:13

What is the difference between using :references and :belongs_to in the following command?

bin/rails generate scaffold LineItem product:references cart:belongs_to

BTW it’s from the book Agile Web Development with Rails 7 (PragProg) by @rubys @pragdave.

Thank you!

rubys · 13 June 2024 11:51

In some sense, there is no difference: if you look at the code, they actually are aliases of one another:

github.com

rails/rails/blob/4a4b3998300fbebf537b770d842066b13dee5072/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb#L548-L553


      
          def references(*args, **options)
            args.each do |ref_name|
              ReferenceDefinition.new(ref_name, **options).add_to(self)
            end
          end
          alias :belongs_to :references

So they are synonyms at the database level.

At a semantic level, belong to implies a level of ownership. You can think of the cart as “owning” a line item. This is different than the relationship between a line item and a product… a product has an independent existence, and doesn’t “own” line items.

If this makes sense to you, then this is just one of the many ways that Rails helps you express your intent when defining a model. If it doesn’t - don’t worry to much about it, because ultimately these two terms are synonyms.

pillaiindu · 13 June 2024 12:52

Thank you @rubys !

This makes sense now.