How to control model display names in Active Admin

# Problem Active Admin automatically chooses how to show a model when it needs a human-readable label (for example in dropdowns or resource headings). By default it looks for a few methods on the model and falls back to a generic "ModelName #id" if none match. That can be fine for many apps, but causes issues when your model has a name attribute that needs different formatting in the admin, or when a display_name attribute exists but is sometimes nil.

# Solutions There are two straightforward approaches you can use without changing Active Admin itself.

1) Add a display_name method to the model

• Return the formatted string that should be used in admin UI

Use this when you want a single, consistent admin label and you can modify the model directly.

2) Customize Active Admin's lookup order

If you can't or don't want to alter the model's existing display_name/name/to_s behavior, change the order of methods Active Admin checks. In config/initializers/active_admin.rb set config.display_name_methods to the array of method names you want Active Admin to try, in order.

• Add a custom method name (active_admin_display_name) that returns the intended admin label.
• Override Active Admin's defaults with: config.display_name_methods = %i[active_admin_display_name display_name name to_s]

This makes active_admin_display_name take precedence. If it returns nil or is not defined, Active Admin moves to display_name, then name, then to_s.

# Why you'd pick each approach

• Add display_name on the model when you own the model code and want a single method name to represent display across the app.
• Customize config.display_name_methods when the model already exposes attributes or methods used elsewhere, or when you need a different admin-only representation without touching existing methods.

# Example model method (idea only)

# Practical notes

• If an attribute like display_name exists but is sometimes nil, Active Admin will fall back to the next available method. That can produce labels like "ModelName #1234", so prefer the config override or a dedicated active_admin_display_name to avoid that fallback.

# Short checklist

• If you can change the model: implement display_name.
• If you need admin-specific behavior: add active_admin_display_name and update config.display_name_methods to prefer it.
• Test lists and dropdowns where model labels are used to confirm the new strings appear.