nested has_one

[haroldus-]

Should there not be support for a nested has_one as well as nested has_many (referenced in this issue)?

Here is how I am implementing it via custom field (it is quite similar to nested has_many but a bit simpler):

#/app/madmin/fields/nested_has_one_field.rb
class NestedHasOneField < Madmin::Field
  DEFAULT_ATTRIBUTES = %w[_destroy id].freeze
  def nested_attributes
    resource.attributes.except(*skipped_fields)
  end

  def resource
    "#{to_model.name}Resource".constantize
  end
  
  # def value(record)
  #   record.public_send(attribute_name)
  # end

  # def to_partial_path(name)
  #   unless %w[index show form].include? name
  #     raise ArgumentError, "`partial` must be 'index', 'show', or 'form'"
  #  end
  #
  #   "/madmin/fields/#{self.class.field_type}/#{name}"
  # end

  def to_param
    {"#{attribute_name}_attributes": permitted_fields}
  end

  # # Used for checking visibility of attribute on an view
  # def visible?(action, default: true)
  #   options.fetch(action.to_sym, default)
  # end

  # def required?
  #   model.validators_on(attribute_name).any? { |v| v.is_a? ActiveModel::Validations::PresenceValidator }
  # end

  def to_model
    attribute_name.to_s.singularize.classify.constantize
  end

  private

  def permitted_fields
    (resource.permitted_params - skipped_fields + DEFAULT_ATTRIBUTES).uniq
  end

  def skipped_fields
    options[:skip] || []
  end
end

<%# /app/views/madmin/fields/nested_has_one_field/_form.html.erb %>
<div class="block md:inline-block md:w-32 flex-shrink-0 text-gray-700">
  <%= render "madmin/shared/label", form: form, field: field %>
</div>
<%= content_tag :div, class: "border border-gray-200 rounded-lg p-5" do %>
  <%= form.fields_for(
    field.attribute_name,
    form.object.public_send(field.attribute_name) || field.to_model.new,
    {}
  ) do |nested_form| %>
    <% field.nested_attributes.each do |name, nested_attribute| %>
      <% next if nested_attribute[:field].nil? %>
      <% next unless nested_attribute[:field].visible?(action_name) %>
      <% next unless nested_attribute[:field].visible?(:form) %>

      <% nested_field = nested_attribute[:field] %>

      <div class="mb-4 flex">
        <%= render(
          partial: nested_field.to_partial_path("form"),
          locals: {
            field: nested_field,
            record: nested_form.object,
            form: nested_form,
            resource: field.resource
          }
        )%>
      </div>
    <% end %>
    <div class="mb-4 flex">
      <div class="block md:inline-block md:w-32 flex-shrink-0 text-gray-700">
        <%= nested_form.label :_destroy %>
      </div>
      <%= nested_form.check_box :_destroy %>
    </div>
  <% end %>
<% end %>

[excid3]

Thanks for sharing this! This would be useful. Would you be interested in making a PR with a demo in test/dummy?

[haroldus-]

Have made the PR for you. One thing that I think would be good, and this applies to the nested has many field as well, is if the nested fields could be turbo streamed into the form with a button instead of using stimulus. I had a little look at adding this functionality but I don't think madmin is using the turbo-rails gem, which means the controller wasn't able to respond to a turbo_stream format request.

[excid3]

We will definitely be switching over as much to Turbo as we can. I plan to swap tom-select for hotwire_combobox for example. 👍