We have a model that belongs to another model which has a composite key, e.g. (fictitious key) [place_id, event_hour, event_min]

belongs_to :place, class_name: "Place", foreign_key: Place.primary_key, optional: true

Expected behavior

The page should load

Actual behavior

When we try to load the page for the model we get an error undefined method 'to_sym' for an instance of Array

#<ActionView::Template::Error: undefined method 'to_sym' for an instance of Array>
/path/to/ruby/version/lib/ruby/gems/3.4.0/gems/activeadmin-3.3.0/lib/active_admin/resource/attributes.rb:24:in 'block in ActiveAdmin::Resource::Attributes#foreign_methods'

https://github.com/activeadmin/activeadmin/blob/master/lib/active_admin/resource/attributes.rb#L24

r.foreign_key.to_sym chokes on the foreign key [place_id, event_hour, event_min]

Suggestions:

If that is a column to view / show, then allow it to handle arrays:

    index_by do |r|
      key = r.foreign_key
      key.is_a?(Array) ? key.join("_").to_sym : key.to_sym
    end

Or reject any non-standard keys so we don't show those columns / links?

def foreign_methods
  @foreign_methods ||= resource_class.reflect_on_all_associations.
    select { |r| r.macro == :belongs_to }.
    reject { |r| r.chain.length > 2 && !r.options[:polymorphic] }.
    reject { |r| !r.foreign_key.is_a?(String) }.
    index_by { |r| r.foreign_key.to_sym }
end

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Sorry, I haven't had time to reproduce. If needed, I will try to do that, but hopefully the issue is apparent above.