TypeError (no implicit conversion of nil into String)

[dev054]

I'm trying to use the experimental feature (track associations) but I'm facing a issue:

I have the following models:

UserVersion:

class UserVersion < PaperTrail::Version
  self.table_name = :user_versions

  belongs_to :user, foreign_key: :whodunnit
end

User:

class User < ApplicationRecord
  has_paper_trail class_name: 'UserVersion'

  has_many :addresses, inverse_of: :user
  accepts_nested_attributes_for :addresses, allow_destroy: true
end

Address:

class Address < ApplicationRecord
  has_paper_trail # <- The error is here

  belongs_to :user, inverse_of: :addresses
end

So, the issue is: associations aren't being tracked when I have a "parent" custom version class...

Always when I try to create/update "addresses", it show the following error:

TypeError (no implicit conversion of nil into String):

If I remove the line has_paper_trail from Address model it works 100% without errors (but, of course, without versioning).

It seems like it searches for the versions (default) table instead of go to user_versions...

I opened a question in SO, however it seems like it's a bug (it's normal in a experimental feature)..

I'm just trying to find a way to do this... even with a workaround.

Thanks in advance.

[jaredbeck]

Hi, thanks for testing the experimental associations tracking feature, and thanks for the bug report. Per our contributing guide please use our bug report template.

[dev054]

Hey @jaredbeck, my script:

# Use this template to report PaperTrail bugs.
# Please include only the minimum code necessary to reproduce your issue.
require "bundler/inline"

# STEP ONE: What versions are you using?
gemfile(true) do
  ruby "2.3.3"
  source "https://rubygems.org"
  gem "activerecord", "5.0.0"
  gem "minitest", "5.9.0"
  gem "paper_trail", require: false
  gem 'pg', '~> 0.18'
end


require "active_record"
require "minitest/autorun"
require "logger"
ActiveRecord::Base.establish_connection(adapter: "postgresql",
                                        database: "api_test",
                                        host: '127.0.0.1',
                                        username: 'postgres',
                                        password: 'postgres')
ActiveRecord::Base.logger = nil
ActiveRecord::Schema.define do
  # STEP TWO: Define your tables here.
  create_table :users, force: true do |t|
    t.text :first_name, null: false
    t.timestamps
  end

  create_table :addresses, force: true do |t|
    t.text :zip_code, null: false
    t.references :user, foreign_key: true, null: false
    t.timestamps
  end

  create_table :user_versions do |t|
    t.string :item_type, null: false
    t.integer :item_id, null: false
    t.string :event, null: false
    t.string :whodunnit
    t.json :object
    t.json :object_changes, null: false
    t.integer :transaction_id
    t.index %i(item_type item_id transaction_id)

    t.timestamps
  end

  create_table :version_associations do |t|
    t.integer  :version_id
    t.string   :foreign_key_name, null: false
    t.integer  :foreign_key_id
  end
  add_index :version_associations, [:version_id]
  add_index :version_associations, %i(foreign_key_name foreign_key_id),
    name: "index_version_associations_on_foreign_key"
end
ActiveRecord::Base.logger = Logger.new(STDOUT)
require "paper_trail/config"

# STEP THREE: Configure PaperTrail as you would in your initializer
PaperTrail::Config.instance.track_associations = true

require "paper_trail"

# STEP FOUR: Define your AR models here.
module PaperTrail
  class Version < ActiveRecord::Base
    include PaperTrail::VersionConcern
    self.abstract_class = true
  end
end

class UserVersion < PaperTrail::Version
  self.table_name = :user_versions

  belongs_to :user, foreign_key: :whodunnit
end

class User < ActiveRecord::Base
  has_paper_trail class_name: 'UserVersion'

  has_many :addresses, inverse_of: :user
  accepts_nested_attributes_for :addresses, allow_destroy: true
end

class Address < ActiveRecord::Base
  has_paper_trail # <- The error is here

  belongs_to :user, inverse_of: :addresses
end

# STEP FIVE: Please write a test that demonstrates your issue.
class BugTest < ActiveSupport::TestCase
  def test_1
    user = User.create(first_name: "Jane")
    user.addresses.create(zip_code: '91239182398')
  end
end

# STEP SIX: Run this script using `ruby my_bug_report.rb`

[jaredbeck]

Thanks! Using your bug report script, I was able to reproduce the TypeError, so I will mark this as a confirmed bug.

Because the associations-tracking feature is experimental, not recommended for production, and still under development, it is not a personal priority for me. (I also do not use it on any of my own projects) However, I'll do what I can to help you develop a fix.

The first step will be to pare down your bug report into a minimal failing test. Questions:

1. Could the json column be a text?
2. Could the database be sqlite?
3. Is the UserVersion class necessary?

[dev054]

1. Yes, it can be, however does it has any effect on this bug? (I changed the columns to :text and it doesn't seem to have a different behavior).
2. Unfortunately, not. I have to use Postgres (it works on sqlite?).
3. Yes, because I don't want to mix all my versioned models in a giant table. I prefer to split (also it has the advantages described in docs.

[jaredbeck]

Thanks. For those questions, I think we should focus on what has an effect on this bug. We want to identify the minimum requirements for reproducing the bug.

[cpfarher]

@jaredbeck same error without association tracking over STI

[jaredbeck]

I'm looking at this more closely and it seems like a misconfiguration.

Every model that has_paper_trail must have a concrete version model, ie. that version model must have a table.

In the provided bug report, UserVersion has a table, but PaperTrail::Version does not. It's fine for PaperTrail::Version to be an abstract_class, but has_paper_trail needs a concrete subclass, eg. AddressVersion.

I think we can easily help people avoid this misconfiguration by raising an error if has_paper_trail is told to use an abstract_class.

What do you think?

[jaredbeck]

Closed by #1040 to be released in 9.0.0