Nested `accepts_nested_attributes_for` hitting `undefined method 'with_indifferent_access'` - ruby-on-rails-5

Question

I'm writing specs for creating a new account. Here's the situation:
Ruby 2.5.0, Rails 5.2.0.rc1
class Account
has_many :accounts_users, inverse_of: :account
has_many :users, through: :accounts_users
has_one :owner, -> { AccountsUser.admins.order(:id) }, class_name: 'AccountsUser'
accepts_nested_attributes_for :owner
end
class AccountsUser
belongs_to :account, inverse_of: :accounts_user
belongs_to :user, autosave: true, inverse_of: :accounts_user
accepts_nested_attributes_for :user
end
class User
has_many :accounts, through: :accounts_users
has_many :accounts_users, autosave: true, dependent: :destroy, inverse_of: :user
accepts_nested_attributes_for :accounts_users, reject_if: :all_blank
end
# AccountsController#account_create_params
params.require(:account).permit(
:plan_id,
:name,
:subdomain,
{
owner_attributes: {
user_attributes: [
:email,
:first_name,
:last_name
]
}
}
)
# rspec account_create_params
let(:valid_account_params) do
{
plan_id: plan.id,
name: 'Name',
subdomain: 'subdomain',
owner_attributes: {
user_attributes: [
email: 'jane#doe.com',
first_name: 'Jane',
last_name: 'Doe'
]
}
}
end
#account = Account.new(account_create_params)
#> NoMethodError: undefined method `with_indifferent_access' for #<Array:0x000056472e0799c0>
from /usr/local/bundle/gems/activerecord-5.2.0.rc1/lib/active_record/nested_attributes.rb:412:in `assign_nested_attributes_for_one_to_one_association'
It has to be complaining about the user_attributes array, and seeing as it's coming from a method called assign_nested_attributes_for_one_to_one_association, Rails seems to be erroneously thinking that the relationship between AccountsUsers and Users is one to one and not one to many.
I've triple checked the associations. What do you guys think? Rails 5.2 bug perhaps?

Answer 1

There were several issues here. I found that permitting parameters and providing them needed different syntax:
def account_create_params
params.require(:account).permit(
:plan_id,
:name,
:subdomain,
{
owner_attributes: {
user_attributes: [
:email,
:first_name,
:last_name,
:password
]
}
}
)
end
vs
let(:valid_account_params) do
{
plan_id: plan.id,
name: 'Name',
subdomain: 'subdomain',
owner_attributes: {
user_attributes: {
email: email_valid,
first_name: 'Jane',
last_name: 'Doe',
password: 'password'
}
}
}
end
A bit confusing there but it works. The inverse_of on AccountsUser was wrong. I needed plural:
belongs_to :account, inverse_of: :accounts_users, optional: true
belongs_to :user, autosave: true, inverse_of: :accounts_users
And I also needed optional: true on the account belongs to, despite accepts_nested_attributes_for setting up the relationship properly. There was a chicken vs egg situation where the AccountsUser was invalid because the Account didn't exist, and the Account couldn't be saved because the AccountsUser was invalid. This may be a Rails 5 'feature'.