false values not displayed in show view when compact_show_view is set to true

[benhutton]

I want to keep compact_show_view = true, which I understand to be defined as "anything non-nil should show up in show view"

I have a boolean field, and thus I want it to show up in show view when it is set to false:

> false.nil?
 => false

The show template does properly use #nil? as the check for whether or not to display values:

- unless values[index].nil? && RailsAdmin::config.compact_show_view

The problem is that the values array is constructed by calling #presence on the formatted_value:

values = fields.map{ |f| f.formatted_value.presence }

Unfortunately,

> false.presence
 => nil

so

> false.presence.nil?
 => true

[begedin]

👍 for this.

As an additional argument for this being considered a bug, we have a pretty_value defined for the boolean field type at https://github.com/sferik/rails_admin/blob/master/lib/rails_admin/config/fields/types/boolean.rb#L13

register_instance_option :pretty_value do
  case value
  when nil
    %(<span class='label label-default'>&#x2012;</span>)
  when false
    %(<span class='label label-danger'>&#x2718;</span>)
  when true
    %(<span class='label label-success'>&#x2713;</span>)
  end.html_safe
end