undefined method '<<' for nil:NilClass

[geeofree]

I have two models that has a has_one and belongs_to association with one another i.e

class User < ActiveRecord::Base
    has_one :hammer, dependent: :destroy
    accepts_nested_attributes_for :hammer, allow_destroy: true
end

class Hammer < ActiveRecord::Base
    belongs_to :user
end

After creating said models, I went on to make a form with these nested models following the documentation for it. However, I couldn't do so because I keep having this undefined method '<<' for nil:NilClass error that points to this particular code on the stacktrace

Snippet of the code I'm using that makes this happen:

form do |f|
    f.inputs 'User Information' do
        # user information inputs
    end

   f.inputs 'Hammer Information' do
       # below is where the error happens
       f.has_many :hammer do |h|
       end
   end
end

Is there anyway I can fix this?

Version of ActiveAdmin and Rails I'm currently using if it's needed:

• activeadmin (1.0.0pre1)
• activeadmin_addons (1.2.0)
• Rails 4.2.6

Thanks in advance!

[geeofree]

Closing.. Updating the activeadmin gem to 1.2.1 fixed it. Sorry 😅

[geeofree]

Reopening: Had to rollback to 1.0.0.pre1 because I was notified by my team lead that it had broke a dependency on the project.

Is there anyway to fix this with the 1.0.0.pre1 version?

Are there versions that I could update into that wouldn't break dependencies perhaps?

Edit:
For clarification on the dependency that broke, it was the jquery-date-picker iirc.

[varyonic]

I don't think there is any interest in back-porting to a pre-release. You will have better luck opening a fresh issue concerning dependencies.

[geeofree]

@varyonic okay, will do. Thanks!

[geeofree]

Closing again. No other solution than to upgrade along with missing dependencies. 😅 🐢

[pragun16]

This thread is the only place I found my exact problem discussed but sadly upgrading was not a solution in my case. I opted for generating the nested attribute form like this which worked for me.

f.inputs "Field", for: [:model_name, f.object.model_name] do |p|
   p.input :field1
   p.input :field2
end