Add if option to conditionally hide a collection action

[guewen]

Here's a way to conditionally hide collection actions.
It may be useful to check permissions or even to hide actions depending on the current scope/filters as we have access to the current params[:q] and params[:scope].

Closes #41

[guewen]

Hi @workgena, thanks for this useful gem!

I proposed this PR and another one (#47), any chance to have them in a release once reviewed / tests ok?

I was not able to run tests locally (undefined method assets' for an instance of Rails::Application::Configurationwhen runningrake setup`), so I'm not sure tests actually pass.

[workgena]

@guewen Thank you for PR.

I'm not actively working with ActiveAdmin nowadays, so I would need more time to see how it works. I have this page open in the browser as a reminder.

[guewen]

Hi, thanks for answering @workgena!

I finally resorted to only using activeadmin's DSL only, which was enough for my needs, something such as (a bit simplified here):

  sidebar I18n.t('active_admin.actions.batch_export.sidebar.title'),
          only: :index do
    if params[:q] || params[:scope]
      para(I18n.t('active_admin.actions.batch_export.sidebar.help'))

      if can?(:export_csv, Order)
        div(
          link_to(I18n.t('active_admin.actions.batch_export.buttons.csv'),
                  batch_export_csv_admin_orders_path(params.slice(:q, :scope).permit!),
                  method: :post,
                  class: 'button btn')
        )
      end
    else
      para(I18n.t('active_admin.actions.batch_export.sidebar.help_no_filter'))
    end
  end

  collection_action :batch_export_csv, method: :post do
    ExportOrdersCsvJob.perform_async(batch_action_collection.pluck(:id), current_user.id)
  end

So I'm finally not using your gem. If you prefer, I can close my pull requests, but I'd happily follow up if there is more interest for this.