Incompatibility with Rails 7.1.3 and Administrate 0.20.1

[mrjonesbot]

It looks like ActionView raises a NoMethodError when attempting to render the form.

undefined method 'new_record?' for nil::NilClass

at: is_dynamic = f.object.new_record?

Full backtrace: https://gist.github.com/mrjonesbot/ce4c9923ddaabba7b5cfbff391417f8f

[thogg4]

Had this same issue.
I was able to fix it by making sure accepts_nested_attributes_for was defined in the model that contained the has_many association.

[nickcharlton]

Hm! Is this something someone could add a note in the README for? I imagine missing off accepts_nested_attributes_for is a common hurdle people face.

[saygun]

When the name of the association is different than the actual class name, the issue persists even when accepts_nested_attributes_for is defined.

has_many :followers, class_name: "User", dependent: :destroy
accepts_nested_attributes_for(
  :followers,
  allow_destroy: true,
  reject_if: :all_blank
)