gregbell/active_admin — pull request #1207 by huk (2012-04-05 13:34:39+00:00)
Title: Show correct display_name in breadcrumb

If resource has finder other than id, uncorrect name is displayed in breadcrumbs.

Example:

```ruby
ActiveAdmin.register Customer do
controller do
defaults :finder => :find_by_uuid
end
end

class Customer < ActiveRecord::Base
def display_name
some_model_attribute
end

def to_param
uuid
end
end
```

In this example, breadcrumb in edit will be something like 'admin/customers/d7b98c74-7f0b-11e1-9e6d-001cc097f0b7', even if in customer model there is display_name method.

So I created quick fix for this - it requires additional class method in model - default_finder. This method have to returns symbol for finder method:

```ruby
class Customer < ActiveRecord::Base
def self.default_finder
:find_by_uuid
end
end
```

After that, breadcrumbs will be 'admin/customer/some_model_attribute', where some_model_attribute is value returned by display_name.