Today I wanted to achieve the following:

Change the key for the parent resource when accessed in the nested resources

# instead of
/collections/:collection_id/entries

# wanted article_id
/collections/:article_id/entries

I also wanted to have the EntriesController scoped within the Collections module:

# instead of 
class EntriesController
...
end

# wanted
class Collections::EntriesController
...
end

What did not worked

I first tried to use the param option for the resources. See documentation here

resources :collections, only: %i(show) param: :article_id do
  resources :entries, only: %i(index), module: :collections
end

But it does not work.

If you run rails routes -g collections you will notice the following response:

# route helper 
collection_entries

# HTTP route
GET /collections/:collection_article_id/entries

# controller
Collections::EntriesController

Notice collection_article_id inside the route /collections/:collection_article_id/entries which is not what I wanted:

- /collections/:collection_article_id/entries
+ /collections/:article_id/entries

Solution: use as

The option as allows to change the route helper and it seems that this way Rails will also change the name of the param key when using nested resources.

resources :collections, only: %i(show) as: :articles do
  resources :entries, only: %i(index), module: :collections
end

Will generate:

# route helper 
article_entries

# HTTP route
GET /collections/:article_id/entries

# controller
Collections::EntriesController

I am not sure if this is a bug or not in how the param option works.