Add possibility to define reusable params.

[dm1try]

Another one concept :)

Examples:

helpers do
  params :pagination do
    optional :page, type: Integer
    optional :per_page, type: Integer   
  end
end

desc "Get collection"
params do
  use :pagination
end

using module:

# shared_params.rb
module SharedParams
  extend Grape::ApiHelpers

  params :period do
    optional :start_date
    optional :end_date
  end

  params :pagination do
    optional :page, type: Integer
    optional :per_page, type: Integer   
  end
end

helpers SharedParams

desc "Get collection"
params do
  use :pagination, :period
end

[dm1try]

@dblock what do you think ?

[dblock]

(edited)

I like the part where you can define params within helpers, that's perfect.

I am a bit worried that ApiHelpers is going to be getting more and more functionality that copies Api. So I wonder whether this means we should be doing some serious refactoring to avoid duplicating things? Or a more generic meta-programming idea could be that ApiHelpers takes anything via method_missing, remembers it and invokes it in the context of the API?

[dblock]

@dm1try Btw, whichever way we go, this is a very elegant approach - you, sir, are a Ruby 師匠

[dm1try]

@dblock , thanks for feedback!
Ok, lets talk about more generic way, we can try to use ApiHelpers like some proxy to API with allowed methods:

module ApiHelpers
  ALLOWED_METHODS = [:params]
  def method_missing(name, *args, &block)
    ALLOWED_METHODS.include?(name) ? save_lazy_methods : super
  end

  def api_changed(new_api)
    call_lazy_methods
  end
end

The problem is that we should extend API with methods which can be used only in helpers, but now we can do some confusing things:

helpers do
  params do
  end
end

desc 'Get'
params :params do
end

And the main problem is that helpers are used to extend Endpoint on the fly, and maybe it's not worth to mix them with API helpers, and we will have more loosely coupled components 👏

What do the community think? Should we continue?)

[dm1try]

About "serious refactoring",
I don't know how to do this without breaking compatibility, for now.

[dblock]

Ok, I think I agree with you, ApiHelpers is fine.

Do you think this should be defined as an inner class of Api? Like Api::Helpers?

Add README and CHANGELOG and I am happy to merge this.

[dm1try]

@dblock hey, thanks for suggestion. I put API::Helpers at the bottom of API as inner module. Added some README.

Can you take a look?

[dblock]

The extra dot after params is driving me crazy :)

[dm1try]

nice catch :)

[dblock]

Perfect, merging.

[dm1try]

Great ❤️