Ruby on Rails passing an empty hash for nested class creates entities with null values

Question

When using accepts_nested_attributes_for in my project, if any of my nested attributes' hash has a nil value then I get an error saying,

NoMethodError: undefined method 'with_indifferent_access' for nil:NilClass`.

If I replace that nil value with an empty HashWithIndifferentAccess then the nested entity gets created with NULL values.

Is there any way to avoid trying to create an entity if the attributes hash is nil or should I just delete that attributes hash from the hash?

class User < ActiveRecord::Base
  has_one :user_info, autosave: true
  accepts_nested_attributes_for :user_info
end

class UserInfo < ActiveSupport::Base
  belongs_to :user
  has_one :user_identifier, autosave: true
  accepts_nested_attributes_for :user_identifier
end

class UserIdentifier < ActiveSupport::Base
  belongs_to :user_info
end

When I try to create a new User:

hash = {follower_count: 10 , user_info_attributes: { user_identifier_attributes: nil } }

usr = User.new(hash)

If any of my attribute hashes is nil (like user_identifier_attributes above) then I get:

NoMethodError: undefined method `with_indifferent_access' for nil:NilClass

But then if I set nil attributes to a new HashWithIndifferentAccess in my initialize method then the entity gets created with NULL values.

class UserIdentifier < ActiveSupport::Base
  belongs_to :user_info

  def initialize(attributes = nil)
        attributes[:user_identifier_attributes] = attributes.delete(:user_identifier) || HashWithIndifferentAccess.new
  end
end

hash = {follower_count: 10 , user_info_attributes: { user_identifier_attributes: nil } }
usr = User.new(hash)
usr.user_info.user_identifier # => #<UserIdentifier:0x0000559a30c32380 id: nil, user_info_id: nil, name: nil, value: nil>

Why do you pass `user_info_attributes: { user_identifier_attributes: nil }` to `User.new` when there is no data available? Where does that hash come from? A from? — spickermann, Jun 12 '20 at 13:37
It just comes from an API call. I don't have a rails project. I am just using `ActiveRecord` for the DB. — Burak Kaymakci, Jun 12 '20 at 13:39
When you do not want to create a user_info and a user_identifier with the user then do not send empty hashes, just skip the nested hashes at all. — spickermann, Jun 12 '20 at 13:44
Oh, so I should handle the hash before passing it to `User.new`. Alright, thank you. :) — Burak Kaymakci, Jun 12 '20 at 13:45
Yes in your example, weh you do not want to create an info and an identifier, send only `{ follower_count: 10 }` to your API — spickermann, Jun 12 '20 at 13:48
Alright, I will handle that hash outside my `User` class and then pass it. — Burak Kaymakci, Jun 12 '20 at 13:58

Ruby on Rails passing an empty hash for nested class creates entities with null values

0 Answers0