Question

我在Rails项目上工作，使用Rails 4.2.0，gemfile：

gem 'rails', '4.2.0'
# other gems.........

我们有这两个模型：

class shop < ActiveRecord::Base
  has_many :shop_categories
end

class ShopCategory < ActiveRecord::Base
  # has a column named "shop_id"
  belongs_to :shop

  def self.some_max(shop)
    # line number: 33
    where(shop: shop).maximum(:some_value)
  end
end

我们有一个生成器，它将在ShopCategory上调用“some_max”方法：

# simplified, but just like this
shop = Shop.first
# lib/generators/shop/build/build_generator.rb:36
ShopCategory.some_max shop

并且我们的Rails应用程序中的代码调用了生成器：

# app/services/shop_service.rb:8
Rails::Generators.invoke 'shop:build', [..params..]

我们收到此错误：

  NoMethodError (undefined method `convert_value_to_association_ids' for ActiveRecord::PredicateBuilder:Class):
  composite_primary_keys (8.1.3) lib/composite_primary_keys/relation/predicate_builder.rb:24:in `expand'
  activerecord (4.2.0) lib/active_record/relation/predicate_builder.rb:43:in `block in build_from_hash'
  activerecord (4.2.0) lib/active_record/relation/predicate_builder.rb:21:in `each'
  activerecord (4.2.0) lib/active_record/relation/predicate_builder.rb:21:in `build_from_hash'
  activerecord (4.2.0) lib/active_record/relation/query_methods.rb:958:in `build_where'
  activerecord (4.2.0) lib/active_record/relation/query_methods.rb:584:in `where!'
  activerecord (4.2.0) lib/active_record/relation/query_methods.rb:574:in `where'
  activerecord (4.2.0) lib/active_record/querying.rb:10:in `where'
  app/models/shop_category.rb:33:in `block in <class:ShopCategory>'
  activerecord (4.2.0) lib/active_record/scoping/named.rb:155:in `call'
  activerecord (4.2.0) lib/active_record/scoping/named.rb:155:in `block (2 levels) in scope'
  activerecord (4.2.0) lib/active_record/relation.rb:302:in `scoping'
  activerecord (4.2.0) lib/active_record/scoping/named.rb:155:in `block in scope'
  app/models/shop_category.rb:28:in `block in <class:ShopCategory>'
  activesupport (4.2.0) lib/active_support/callbacks.rb:443:in `instance_exec'
  activesupport (4.2.0) lib/active_support/callbacks.rb:443:in `block in make_lambda'
  activesupport (4.2.0) lib/active_support/callbacks.rb:163:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:163:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `_run_callbacks'
  activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_create_callbacks'
  activerecord (4.2.0) lib/active_record/callbacks.rb:306:in `_create_record'
  activerecord (4.2.0) lib/active_record/timestamp.rb:57:in `_create_record'
  activerecord (4.2.0) lib/active_record/persistence.rb:501:in `create_or_update'
  activerecord (4.2.0) lib/active_record/callbacks.rb:302:in `block in create_or_update'
  activesupport (4.2.0) lib/active_support/callbacks.rb:117:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:117:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:219:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `_run_callbacks'
  activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_save_callbacks'
  activerecord (4.2.0) lib/active_record/callbacks.rb:302:in `create_or_update'
  activerecord (4.2.0) lib/active_record/persistence.rb:120:in `save'
  activerecord (4.2.0) lib/active_record/validations.rb:37:in `save'
  activerecord (4.2.0) lib/active_record/attribute_methods/dirty.rb:21:in `save'
  activerecord (4.2.0) lib/active_record/transactions.rb:286:in `block (2 levels) in save'
  activerecord (4.2.0) lib/active_record/transactions.rb:347:in `block in with_transaction_returning_status'
  activerecord (4.2.0) lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `block in transaction'
  activerecord (4.2.0) lib/active_record/connection_adapters/abstract/transaction.rb:188:in `within_new_transaction'
  activerecord (4.2.0) lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `transaction'
  activerecord (4.2.0) lib/active_record/transactions.rb:220:in `transaction'
  activerecord (4.2.0) lib/active_record/transactions.rb:344:in `with_transaction_returning_status'
  activerecord (4.2.0) lib/active_record/transactions.rb:286:in `block in save'
  activerecord (4.2.0) lib/active_record/transactions.rb:301:in `rollback_active_record_state!'
  activerecord (4.2.0) lib/active_record/transactions.rb:285:in `save'
  activerecord (4.2.0) lib/active_record/associations/singular_association.rb:79:in `_create_record'
  activerecord (4.2.0) lib/active_record/associations/singular_association.rb:21:in `create'
  activerecord (4.2.0) lib/active_record/associations/builder/singular_association.rb:22:in `create_shop_category'
  lib/generators/shop/build/build_generator.rb:36:in `create_shop_category'
  lib/generators/shop/build/build_generator.rb:30:in `copy_shop_files'
  thor (0.19.1) lib/thor/command.rb:27:in `run'
  thor (0.19.1) lib/thor/invocation.rb:126:in `invoke_command'
  thor (0.19.1) lib/thor/invocation.rb:133:in `block in invoke_all'
  thor (0.19.1) lib/thor/invocation.rb:133:in `each'
  thor (0.19.1) lib/thor/invocation.rb:133:in `map'
  thor (0.19.1) lib/thor/invocation.rb:133:in `invoke_all'
  thor (0.19.1) lib/thor/group.rb:232:in `dispatch'
  thor (0.19.1) lib/thor/base.rb:440:in `start'
  railties (4.2.0) lib/rails/generators.rb:157:in `invoke'
  app/services/shop_service.rb:8:in `build'
  app/controllers/after_registers_controller.rb:180:in `go_shop_step'
  app/controllers/after_registers_controller.rb:107:in `go_retail_steps'
  app/controllers/after_registers_controller.rb:46:in `update'
  actionpack (4.2.0) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
  actionpack (4.2.0) lib/abstract_controller/base.rb:198:in `process_action'
  actionpack (4.2.0) lib/action_controller/metal/rendering.rb:10:in `process_action'
  actionpack (4.2.0) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
  activesupport (4.2.0) lib/active_support/callbacks.rb:117:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:117:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:151:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:151:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:151:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:151:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:151:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:151:in `block in halting_and_conditional'
  activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:234:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:169:in `block in halting'
  activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:92:in `_run_callbacks'
  activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_process_action_callbacks'
  activesupport (4.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
  actionpack (4.2.0) lib/abstract_controller/callbacks.rb:19:in `process_action'
  actionpack (4.2.0) lib/action_controller/metal/rescue.rb:29:in `process_action'
  actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:31:in `block in process_action'
  activesupport (4.2.0) lib/active_support/notifications.rb:164:in `block in instrument'
  activesupport (4.2.0) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
  activesupport (4.2.0) lib/active_support/notifications.rb:164:in `instrument'
  actionpack (4.2.0) lib/action_controller/metal/instrumentation.rb:30:in `process_action'
  actionpack (4.2.0) lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
  activerecord (4.2.0) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
  actionpack (4.2.0) lib/abstract_controller/base.rb:137:in `process'
  actionview (4.2.0) lib/action_view/rendering.rb:30:in `process'
  actionpack (4.2.0) lib/action_controller/metal.rb:195:in `dispatch'
  actionpack (4.2.0) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
  actionpack (4.2.0) lib/action_controller/metal.rb:236:in `block in action'
  actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:73:in `call'
  actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
  actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:42:in `serve'
  actionpack (4.2.0) lib/action_dispatch/journey/router.rb:43:in `block in serve'
  actionpack (4.2.0) lib/action_dispatch/journey/router.rb:30:in `each'
  actionpack (4.2.0) lib/action_dispatch/journey/router.rb:30:in `serve'
  actionpack (4.2.0) lib/action_dispatch/routing/route_set.rb:802:in `call'
  rack-raw-upload (1.1.1) lib/rack/raw_upload.rb:18:in `call'
  warden (1.2.6) lib/warden/manager.rb:35:in `block in call'
  warden (1.2.6) lib/warden/manager.rb:34:in `catch'
  warden (1.2.6) lib/warden/manager.rb:34:in `call'
  rack (1.6.4) lib/rack/etag.rb:24:in `call'
  rack (1.6.4) lib/rack/conditionalget.rb:38:in `call'
  rack (1.6.4) lib/rack/head.rb:13:in `call'
  remotipart (1.2.1) lib/remotipart/middleware.rb:27:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/flash.rb:260:in `call'
  rack (1.6.4) lib/rack/session/abstract/id.rb:225:in `context'
  rack (1.6.4) lib/rack/session/abstract/id.rb:220:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/cookies.rb:560:in `call'
  activerecord (4.2.0) lib/active_record/query_cache.rb:36:in `call'
  activerecord (4.2.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:647:in `call'
  activerecord (4.2.0) lib/active_record/migration.rb:378:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:88:in `call'
  activesupport (4.2.0) lib/active_support/callbacks.rb:88:in `_run_callbacks'
  activesupport (4.2.0) lib/active_support/callbacks.rb:734:in `_run_call_callbacks'
  activesupport (4.2.0) lib/active_support/callbacks.rb:81:in `run_callbacks'
  actionpack (4.2.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/reloader.rb:73:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
  web-console (2.3.0) lib/web_console/middleware.rb:20:in `block in call'
  web-console (2.3.0) lib/web_console/middleware.rb:18:in `catch'
  web-console (2.3.0) lib/web_console/middleware.rb:18:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
  railties (4.2.0) lib/rails/rack/logger.rb:38:in `call_app'
  railties (4.2.0) lib/rails/rack/logger.rb:20:in `block in call'
  activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `block in tagged'
  activesupport (4.2.0) lib/active_support/tagged_logging.rb:26:in `tagged'
  activesupport (4.2.0) lib/active_support/tagged_logging.rb:68:in `tagged'
  railties (4.2.0) lib/rails/rack/logger.rb:20:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
  rack (1.6.4) lib/rack/methodoverride.rb:22:in `call'
  rack (1.6.4) lib/rack/runtime.rb:18:in `call'
  activesupport (4.2.0) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
  rack (1.6.4) lib/rack/lock.rb:17:in `call'
  actionpack (4.2.0) lib/action_dispatch/middleware/static.rb:113:in `call'
  rack-cors (0.4.0) lib/rack/cors.rb:80:in `call'
  railties (4.2.0) lib/rails/engine.rb:518:in `call'
  railties (4.2.0) lib/rails/application.rb:164:in `call'
  rack (1.6.4) lib/rack/content_length.rb:15:in `call'
  thin (1.6.4) lib/thin/connection.rb:86:in `block in pre_process'
  thin (1.6.4) lib/thin/connection.rb:84:in `catch'
  thin (1.6.4) lib/thin/connection.rb:84:in `pre_process'
  thin (1.6.4) lib/thin/connection.rb:53:in `process'
  thin (1.6.4) lib/thin/connection.rb:39:in `receive_data'
  eventmachine (1.2.0.1) lib/eventmachine.rb:194:in `run_machine'
  eventmachine (1.2.0.1) lib/eventmachine.rb:194:in `run'
  thin (1.6.4) lib/thin/backends/base.rb:73:in `start'
  thin (1.6.4) lib/thin/server.rb:162:in `start'
  rack (1.6.4) lib/rack/handler/thin.rb:19:in `run'
  rack (1.6.4) lib/rack/server.rb:286:in `start'
  railties (4.2.0) lib/rails/commands/server.rb:80:in `start'
  railties (4.2.0) lib/rails/commands/commands_tasks.rb:80:in `block in server'
  railties (4.2.0) lib/rails/commands/commands_tasks.rb:75:in `tap'
  railties (4.2.0) lib/rails/commands/commands_tasks.rb:75:in `server'
  railties (4.2.0) lib/rails/commands/commands_tasks.rb:39:in `run_command!'
  railties (4.2.0) lib/rails/commands.rb:17:in `<top (required)>'
  bin/rails:8:in `require'
  bin/rails:8:in `<top (required)>'
  spring (1.7.1) lib/spring/client/rails.rb:28:in `load'
  spring (1.7.1) lib/spring/client/rails.rb:28:in `call'
  spring (1.7.1) lib/spring/client/command.rb:7:in `call'
  spring (1.7.1) lib/spring/client.rb:30:in `run'
  spring (1.7.1) bin/spring:49:in `<top (required)>'
  spring (1.7.1) lib/spring/binstub.rb:11:in `load'
  spring (1.7.1) lib/spring/binstub.rb:11:in `<top (required)>'
  /home/robin/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
  /home/robin/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
  bin/spring:13:in `<top (required)>'
  bin/rails:3:in `load'
  bin/rails:3:in `<main>'


  Rendered /home/robin/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.0/lib/action_dispatch/middleware/templates/rescues/_source.erb (12.4ms)
  Rendered /home/robin/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.0/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (4.1ms)
  Rendered /home/robin/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.0/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.3ms)
  Rendered /home/robin/.rvm/gems/ruby-2.2.3/gems/actionpack-4.2.0/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout (32.8ms)

我理解这个错误发生在Rails尝试转换这一行时：

where(shop: shop).maximum(:some_value)

这样的事情：

# when I change the line above to this, the error disappeared
where(shop_id: shop.id).maximum(:some_value)

另外，我检查了Rails文档，发现ActiveRecord :: PredicateBuilder在Rails版本4.2.1中有一个名为“convert_value_to_association_ids”的类方法，但在4.2.0中没有。那么为什么Rails调用方法在当前版本（4.2.0）中不存在？这与调用生成器的环境有关吗？提前谢谢。

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更新：在我的rails项目中，我运行“bundle show activerecord”，它给我一条到我的activerecord gem的路径，并按照这条路径，我在“lib / active_record / relation / predicate_builder.rb”中打开文件，我不能在此文件中找到类方法“convert_value_to_association_ids”。

Answer 1

The error is actually coming from composite_primary_keys, v8.1.3, not rails/activerecord:

value = convert_value_to_association_ids(value, primary_key)

It uses this method, even though it depends on activerecord 4.2.0, in which the method does not yet exist. It's a bug in that version of the composite_primary_keys gem.

为什么Rails调用方法在当前版本（4.2.0）中不存在？

1 个答案: