ruby-on-rails - 升级ruby和rails版本后has_many关系隐式转换错误

Question

我刚刚升级了我的 Ruby on Rails 项目

ruby 1.9.3-p551 到 ruby 2.3.0

和

rails 3.2.13 到 rails 3.2.22(3-2-稳定)

升级之前没有错误。

在我的用户模型中，我有一些复杂的关系来管理用户的联系人，并且在访问这些关系时，我收到没有将 nil 隐式转换为字符串错误。

关系定义为 -

has_many :contacts, :foreign_key => 'owner_id'
has_many :pending_invited, conditions: {:'contacts.confirmed' => false, :'contacts.denied' => false }, through: :contacts, class_name: 'User', source: :user
has_many :invited, conditions: { :'contacts.confirmed' => true }, through: :contacts, class_name: 'User', source: :user

has_many :inverse_contacts, :foreign_key => 'user_id', :class_name => 'Contact'
has_many :pending_invited_by, conditions: {:'contacts.confirmed' => false, :'contacts.denied' => false }, through: :inverse_contacts, class_name: 'User', source: :owner
has_many :invited_by, conditions: {:'contacts.confirmed' => true }, through: :inverse_contacts, class_name: 'User', source: :owner

has_many :denied, conditions: {:'contacts.denied' => true }, through: :contacts, class_name: 'User', source: :user
has_many :denied_by, conditions: {:'contacts.denied' => true }, through: :inverse_contacts, class_name: 'User', source: :owner

使用rails c我可以通过运行获得完整的堆栈跟踪-

u = User.first
u.pending_invited_by

这会产生以下错误 -

TypeError: no implicit conversion of nil into String
    from .bundle/gems/arel-3.0.3/lib/arel.rb:40:in `initialize'
    from .bundle/gems/arel-3.0.3/lib/arel.rb:40:in `new'
    from .bundle/gems/arel-3.0.3/lib/arel.rb:40:in `sql'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/join_helper.rb:47:in `block in sanitize'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/join_helper.rb:45:in `map'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/join_helper.rb:45:in `sanitize'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/association_scope.rb:94:in `block in add_constraints'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/association_scope.rb:39:in `each'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/association_scope.rb:39:in `each_with_index'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/association_scope.rb:39:in `add_constraints'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/association_scope.rb:31:in `scope'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/association.rb:99:in `association_scope'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/association.rb:88:in `scoped'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/has_many_through_association.rb:178:in `find_target'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/collection_association.rb:335:in `load_target'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/collection_proxy.rb:44:in `load_target'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/activerecord/lib/active_record/associations/collection_proxy.rb:89:in `method_missing'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/railties/lib/rails/commands/console.rb:47:in `start'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/railties/lib/rails/commands/console.rb:8:in `start'
    from .bundle/bundler/gems/rails-f85bbed4cdc1/railties/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'

感谢任何帮助。

Answer 1

事实上，我今天也遇到了这个问题。问题在于现代 Ruby (2.3) 与古老的 ActiveRecord (3.2.22) 的组合。 Ruby 2.2 没有这个问题。

在 Ruby 2.3 中，Hash 响应 to_proc，这会在 ActiveRecord 3.2 中触发意外错误。

检查https://github.com/rails/rails/issues/25010进一步的细节/讨论。

我的临时解决方法是取消定义 Hash.to_proc，因为我 100% 确定我的代码或 gems 还没有使用它:

类哈希 undef_method :to_proc 结尾