ActiveAdmin Forms and date select inputs with Custom Pages

This was a pain in the butt to figure out, so I wanted to share what worked for me.

The code below shows how to register/add a custom page to ActiveAdmin that’s not tied to a specific model or resource, and allows you to change a date input that, when submitted, reloads the page with the date appended to the URL as a parameter (ex: ?d=YYYY-MM-DD). Using a get request was the simplest solution, but you can use a post request too, if needed.

With a get request

ActiveAdmin.register_page 'Marketing' do
  menu label: 'Mktg'
  controller do
    def index
      @date = params[:d]&.to_date || Date.current
    end
  end
  content title: 'Marketing' do
    h2 "Date: #{controller.instance_variable_get(:@date).strftime('%_m/%-d/%y')}"
    form action: "marketing", method: :get do |f|
      label 'Date'
      input :date, type: 'date', name: 'd', value: controller.instance_variable_get(:@date)
      input :submit, type: :submit, value: 'Update'
    end
  end
end

With a post request

ActiveAdmin.register_page 'Marketing' do
  menu priority: 2, label: 'Mktg'
controller do
    def index
      @date = params[:d]&.to_date || Date.current
    end
  end
  # page_action used by post request
  page_action :set_date, method: :post do
    redirect_to "/admin/marketing?d=#{params[:d]}"
  end
  content title: 'Marketing' do
    h2 "Date: #{controller.instance_variable_get(:@date).strftime('%_m/%-d/%y')}"
    # action and method changed here
    form action: "marketing/set_date", method: :post do |f|
      label 'Date'
      input :date, type: 'date', name: 'd', value: controller.instance_variable_get(:@date)
      # this is needed when using a post request
      input :authenticity_token, type: :hidden, name: :authenticity_token, value: form_authenticity_token
      input :submit, type: :submit, value: 'Update'
    end
  end
end

Reference links:

• Adding forms to ActiveAdmin custom pages
• StackOverflow: Active Admin create form in register_page

ActiveAdmin’s docs are all unfortunately sparse:

• ActiveAdmin Custom Pages docs
• ActiveAdmin Arbre Components
• Arbre Docs

I hope this was helpful!