How do I index polymorphic (STI) models in Rails 5 with Thinking Sphinx without a circular dependency?

Question

I'm integrating a simple indexed search for a rails 5.1.4 application, using Sphinx 2.2.11-id64-release (95ae9a6) and thinking_sphinx v 4.0.0

Expected behavior:

When I submit a new search, I expect to see either an empty array [] or a set of search results.

Actual behavior:

When I submit a new search with empty parameters from the view layer and try to access the ThinkingSphinx::Search object via a binding.pry in the controller action, rails throws a ActionView::Template::Error (Circular dependency detected while autoloading constant StudentLesson)

[1] pry(main)> ThinkingSphinx.search ''
=> [#<ThinkingSphinx::Search:0x2b0925399e10>
[2] pry(main)> _.inspect
RuntimeError: Circular dependency detected while autoloading constant StudentLesson
from /home/kf/.rvm/gems/ruby-2.4.3@crm/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:509:in `load_missing_constant'
[3] pry(main)>

Code snippets:

class Lesson < ApplicationRecord
  LESSON_TYPES = {
    'StudentLesson': StudentLesson,
    'ProfessionalLesson': ProfessionalLesson
  }.freeze
end

class StudentLesson < Lesson
  after_save ThinkingSphinx::RealTime.callback_for(:student_lesson)
end

class ProfessionalLesson < Lesson
  after_save ThinkingSphinx::RealTime.callback_for(:professional_lesson)
end

# app/indices/student_lesson_index.rb
ThinkingSphinx::Index.define :student_lesson, with: :real_time do
  indexes name, sortable: true
end

# app/indices/professional_lesson_index.rb
ThinkingSphinx::Index.define :professional_lesson, with: :real_time do
  indexes name, sortable: true
end

class SearchesController < ApplicationController
  def index
    @results = []
  end

  def create
    @results = ThinkingSphinx.search(params[:search])
    render :index
  end
end

<div class="collapse navbar-collapse" id="header-navbar">
   <%= render 'layouts/nav_links' %>
   <%= form_for searches_path do %>
     <%= search_field_tag :search, params[:search] %>
     <%= submit_tag 'Search', name: nil, method: :get %>
   <% end %>
 </div>

Here's the dev.sphinx.conf

indexer
{
}

searchd
{
  listen = 127.0.0.1:9306:mysql41
  log = /home/myapp/log/development.searchd.log
  query_log = /home/myapp/log/development.searchd.query.log
  pid_file = /home/myapp/log/development.sphinx.pid
  workers = threads
  binlog_path = /home/myapp/tmp/binlog/development
}

index game_core
{
  type = rt
  path = /home/myapp/db/sphinx/development/game_core
  docinfo = extern
  rt_field = sphinx_internal_class_name
  rt_field = name
  rt_field = summary
  rt_attr_uint = sphinx_deleted
  rt_attr_bigint = sphinx_internal_id
  rt_attr_timestamp = created_at
  rt_attr_timestamp = updated_at
  rt_attr_string = sphinx_internal_class
  rt_attr_string = name_sort
}

index lesson_core
{
  type = rt
  path = /home/myapp/db/sphinx/development/lesson_core
  docinfo = extern
  rt_field = sphinx_internal_class_name
  rt_field = name
  rt_field = purpose
  rt_field = meta
  rt_field = supplies
  rt_field = activity
  rt_attr_uint = sphinx_deleted
  rt_attr_bigint = sphinx_internal_id
  rt_attr_timestamp = created_at
  rt_attr_timestamp = updated_at
  rt_attr_string = sphinx_internal_class
  rt_attr_string = name_sort
}

index protocol_core
{
  type = rt
  path = /home/myapp/db/sphinx/development/protocol_core
  docinfo = extern
  rt_field = sphinx_internal_class_name
  rt_field = name
  rt_field = description
  rt_attr_uint = sphinx_deleted
  rt_attr_bigint = sphinx_internal_id
  rt_attr_timestamp = created_at
  rt_attr_timestamp = updated_at
  rt_attr_string = sphinx_internal_class
  rt_attr_string = name_sort
}

index resource_page_core
{
  type = rt
  path = /home/myapp/db/sphinx/development/resource_page_core
  docinfo = extern
  rt_field = sphinx_internal_class_name
  rt_field = header
  rt_field = content
  rt_attr_uint = sphinx_deleted
  rt_attr_bigint = sphinx_internal_id
  rt_attr_timestamp = created_at
  rt_attr_timestamp = updated_at
  rt_attr_string = sphinx_internal_class
  rt_attr_string = header_sort
}

index game
{
  type = distributed
  local = game_core
}

index lesson
{
  type = distributed
  local = lesson_core
}

index protocol
{
  type = distributed
  local = protocol_core
}

index resource_page
{
  type = distributed
  local = resource_page_core
}

Answer 1

I think the issue here is not directly related to Thinking Sphinx - it just errors because it can't load the search results due to the circular dependency in your models - particularly, the LESSON_TYPES constant:

• Thinking Sphinx makes a search call, and in its result set it has at least one StudentLesson instance, so it needs to load that model.
• Loading StudentLesson finds its dependency (as a subclass) on Lesson .
• Loading Lesson finds its dependency (as references to constants) on both StudentLesson and ProfessionalLesson .
• So, StudentLesson is attempted to be loaded again, and hence the endless loop of dependencies.

(FWIW I just confirmed this behaviour in a test Rails app using the model code you've provided, without TS being involved: all I needed to run in a console was StudentLesson.first .)

Answer 2

You have 2 classes which both inherit a constant definition, this looks problematic.

Try moving this constant definition to an initializer:

LESSON_TYPES = {
    'StudentLesson': StudentLesson,
    'ProfessionalLesson': ProfessionalLesson
  }.freeze

Answer 3

解决方案实际上是在注释线程中找到的spring仍然未解决的问题，可通过初始化require_dependency 'lesson' ->来解决，该问题我实际上已经在初始化程序中有了，但将其移至已解决的Rails.application.config.to_prepare块中重新加载问题以及与狮身人面像相关的症状。