Nested content tags in rails 5 view helpers

nested_content_snippet.rb

  # because i can never remember exactly how and when to use concat
  # when building content in helpers
  def nested_content
    content_tag 'div' do
      concat(content_tag 'span', 'span block')
      concat(tag 'br')
      concat(link_to 'root link', root_path)
      concat(tag 'br')
      concat(link_to('#') do
               concat(content_tag 'h2', 'Head \'em off')
               concat(tag 'br')
               content_tag 'div', (content_tag 'span',(concat 'dudue'))
             end)
    end
  end
  
Another Example for Bootstrap 4 with specifying mandatory field etc.

def form_field_tag(type, label, attr, column, opts={})
    content_tag(:div, class: 'form-group row') do
      concat(
        label_tag("#{attr}[#{column}]", class: 'col-lg-3 col-form-label form-control-label') do
          concat label
          concat content_tag(:span, ' *', class: 'text-danger') if opts[:required]
        end
      )
      
      concat(
        content_tag(:div, class: 'col-lg-9') do
          case type
          when 'text_field'
            concat text_field_tag("#{attr}[#{column}]", nil,
                                  class: 'form-control', 'aria-describedby' => opts[:hint_id], 
                                  required: opts[:required])
          when 'text_area'
            concat text_area_tag("#{attr}[#{column}]", nil,
                                  class: 'form-control', 'aria-describedby' => opts[:hint_id], 
                                  required: opts[:required])
          when 'select'
            concat select_tag("#{attr}[#{column}]", options_for_select(opts[:select_options], opts[:selected_option]),
                                  class: 'form-control', 'aria-describedby' => opts[:hint_id], 
                                  required: opts[:required])  
          end
          concat content_tag(:small, opts[:hint], id: opts[:hint_id],
                                     class: 'form-text text-muted')
        end
      )
    end
  end

  = form_field_tag('text_field', 'Source', 'article', 'source', hint: "Ex: journel", hint_id: 'media_SourceHelp', required: true)  
  

Thanks! Still relevant in 2023. Found via https://thepugautomatic.com/2013/06/helpers/