Top-Level custom structs are not recognized

[swilgosz]

Describe the bug

We can define custom structs nested in a module, and then pointing to it via structs_namespace option. It works fine, but it does not work with top-level custom struct classes.

Reasoning: It makes it problematic to update Hanami 1 applications to Hanami 2, because Hanami-Model (Hanami 1) assumed top-level entities to be defined.

Other than that, this behaviour is inconsistent.

To Reproduce

I've written rspec examples for this usecase: https://github.com/swilgosz/rom-factory/commit/b0afeb720110a28104ebc573a935311f4892f942

class User < ROM::Struct
end

factories.define(:user) do |f|
  f.first_name "Jane"
end

factories.define(admin: :user) do |f|
  f.first_name "John"
end

Factory[:user].class
=> ROM::Struct::User
Factory[:admin]
=> ROM::Struct::Admin.class

module Entities
  class User < ROM::Struct
  end
end

factories.define(:user, struct_namespace: Entities) do |f|
  f.first_name "Jane"
end

factories.define(admin: :user, struct_namespace: Entities) do |f|
  f.first_name "John"
end

Factory[:user].class
=> Entities::User
Factory[:admin].class
=> ROM::Struct::Admin

Expected behavior

I expect that either, by passing struct_namespace: nil or by default, ROM-Factory will try to call the top-level structs if they are defined. It should fallback to ROM::Struct::[[FactoryClass]] in the constant is not found, or is not a kind of ROM::Struct

My environment

• Affects my production application: YES
• Ruby version: 3.0.2
• OS: Mac OS

[swilgosz]

I've investigated the topic a little bit more.

Issue 1:

https://github.com/rom-rb/rom-factory/blob/main/lib/rom/factory/factories.rb#L135

In case, the name is a hash (parent is defined), all options are ignored. I guess it's not a big issue, name is a hash only if the parent is defined, and then the rest of options just inherit from parent.

However, this is inconsistent behaviour and I guess it was not intended, but rather overlooked.

I've fixed this: https://github.com/rom-rb/rom-factory/compare/main...swilgosz:rom-factory:fix/top-level-custom-struct-recognition?expand=1

Issue 2:

When we call the builder with struct_namespace: nil or struct_namespace: false, the default struct namespace is pulled from Factories config: https://github.com/rom-rb/rom-factory/blob/main/lib/rom/factory/factories.rb#L209

This makes it impossible to override the struct_namespace with nil, because it'll always fall-back into ROM::Struct

Also fixed in: https://github.com/rom-rb/rom-factory/compare/main...swilgosz:rom-factory:fix/top-level-custom-struct-recognition?expand=1

Issue 3

The above did not fix the test I wrote, because calling relation.struct_namespace(nil), will still set the model on the mapper into ROM::Struct

This, however, is not a behavior of ROM-Factory, but rather problem with relations auto-struct. I got lost when I started to dig into ROM::Relations, so I'd need some help to point me into the right place. cc: @flash-gordon

[solnic]

This is just not supported. struct_namespace is always meant to be set to something. We can tweak it to raise an error if nil is passed.

[swilgosz]

Hm... That's sad. I raised it, becasue hanami-model requires Top-level constants to be entities, and it makes it harder to upgrade big Hanami 1 applications.

Thanks for this, I'll try another approach, tweaking hanami-model instead.

[swilgosz]

BTW: @solnic I guess the easiest would be to patch the documentation instead :).

[solnic]

@swilgosz hmm, what if you set struct_namespace(Object)?

[swilgosz]

I tried that first, there was no effect, but you are the second person suggesting that. I will briefly try again woth some more detailed look tomorrow and will get back to you, thanks!

[swilgosz]

@solnic It worked! It required from me to also add struct_namespace: Object in the repositories, but it actually worked. Thanks!

[solnic]

@swilgosz ah yeah, repositories configure their relations to use a namespace so this makes sense. I'm glad that it worked 🙂