如何在 Rails 中调试 gem？
How can I debug a gem in Rails?
我正在尝试启动我的 rails 服务器，但我收到以下错误跟踪。
我已经注释掉这里提到的行：
4.2.0/lib/audited/auditor.rb:48:in `audited'
from /home/david-vm/Documents/rails_projects/bane/app/models/user.rb:9:in `<class:User>'
，我可以将其设置为 运行，但我不确定为什么会破坏它。所以我在考虑使用 byebug 来追查问题，但似乎无法弄清楚我将如何去做。或者有其他方法可以解决此问题吗？谢谢！
错误
/home/david-vm/.rvm/gems/ruby-2.3.0/gems/tiny_tds-0.7.0/lib/tiny_tds/client.rb:74:in `connect': Server name not found in configuration files (TinyTds::Error)
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/tiny_tds-0.7.0/lib/tiny_tds/client.rb:74:in `initialize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:280:in `new'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:280:in `dblib_connect'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:271:in `connect'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:59:in `initialize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/sqlserver_base.rb:18:in `new'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/sqlserver_base.rb:18:in `sqlserver_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:436:in `new_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:446:in `checkout_new_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/monitor.rb:214:in `mon_synchronize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/monitor.rb:214:in `mon_synchronize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:565:in `retrieve_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_handling.rb:87:in `connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/model_schema.rb:230:in `table_exists?'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/attribute_methods/primary_key.rb:97:in `get_primary_key'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/attribute_methods/primary_key.rb:85:in `reset_primary_key'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/attribute_methods/primary_key.rb:73:in `primary_key'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/audited-activerecord-4.2.0/lib/audited/adapters/active_record.rb:7:in `default_ignored_attributes'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/audited-4.2.0/lib/audited/auditor.rb:48:in `audited'
from /home/david-vm/Documents/rails_projects/bane/app/models/user.rb:9:in `<class:User>'
from /home/david-vm/Documents/rails_projects/bane/app/models/user.rb:1:in `<top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:457:in `load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:457:in `block in load_file'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:647:in `new_constants_in'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:456:in `load_file'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:354:in `require_or_load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:494:in `load_missing_constant'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:184:in `const_missing'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:261:in `const_get'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:261:in `block in constantize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:259:in `each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:259:in `inject'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:259:in `constantize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:566:in `get'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:597:in `constantize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise.rb:377:in `get'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:81:in `to'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:76:in `modules'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:93:in `routes'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:160:in `default_used_route'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:70:in `initialize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise.rb:411:in `new'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise.rb:411:in `add_mapping'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/rails/routes.rb:241:in `block in devise_for'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/rails/routes.rb:240:in `each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/rails/routes.rb:240:in `devise_for'
from /home/david-vm/Documents/rails_projects/bane/config/routes.rb:11:in `block in <top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/actionpack-4.2.0/lib/action_dispatch/routing/route_set.rb:423:in `instance_exec'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/actionpack-4.2.0/lib/action_dispatch/routing/route_set.rb:423:in `eval_block'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/actionpack-4.2.0/lib/action_dispatch/routing/route_set.rb:401:in `draw'
from /home/david-vm/Documents/rails_projects/bane/config/routes.rb:1:in `<top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `block in load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:40:in `each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:40:in `load_paths'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:16:in `reload!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:26:in `block in updater'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/file_update_checker.rb:75:in `execute'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:27:in `updater'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `instance_exec'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `run'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:55:in `block in run_initializers'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `call'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:54:in `run_initializers'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application.rb:352:in `initialize!'
from /home/david-vm/Documents/rails_projects/bane/config/environment.rb:5:in `<top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `block in require'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application.rb:328:in `require_environment!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:142:in `require_application_and_environment!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:67:in `console'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands.rb:17:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'
User.rb
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :ldap_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable
after_destroy :ensure_an_admin_remains
before_create { generate_token(:auth_token) }
# Audit changes made except for the columns as specified below
audited except: [:last_seen_at, :sign_in_count, :last_sign_in_at, :last_sign_in_ip, :password_digest]
has_associated_audits
acts_as_tagger
acts_as_taggable_on :roles
# associations, methods, etc...
end
更新
原来这是一个 DNS 问题，所以即使我的 database.yml 没有改变，服务器名称也不再有效。刚刚添加了更新，以防有人遇到类似问题，可能值得一试。
答案在堆栈跟踪中。它准确地告诉您系统上的哪个文件有错误。该文件来自 gem 或位于计算机的不同部分的事实无关紧要。
/home/david-vm/.rvm/gems/ruby-2.3.0/gems/tiny_tds-0.7.0/lib/tiny_tds/client.rb:74:in `connect': Server name not found in configuration files (TinyTds::Error)
用你的编辑器打开那个文件（或者回溯中任何看起来最合适的文件），在它吹的那一行之前粘贴一个binding.pry（或者byebug，或者调试器，无论你使用什么）在 (74) 上。然后重新启动您的应用程序并进行调试，就好像它是您应用程序中的一个文件一样。
我正在尝试启动我的 rails 服务器，但我收到以下错误跟踪。
我已经注释掉这里提到的行：
4.2.0/lib/audited/auditor.rb:48:in `audited'
from /home/david-vm/Documents/rails_projects/bane/app/models/user.rb:9:in `<class:User>'
，我可以将其设置为 运行，但我不确定为什么会破坏它。所以我在考虑使用 byebug 来追查问题，但似乎无法弄清楚我将如何去做。或者有其他方法可以解决此问题吗？谢谢！
错误
/home/david-vm/.rvm/gems/ruby-2.3.0/gems/tiny_tds-0.7.0/lib/tiny_tds/client.rb:74:in `connect': Server name not found in configuration files (TinyTds::Error)
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/tiny_tds-0.7.0/lib/tiny_tds/client.rb:74:in `initialize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:280:in `new'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:280:in `dblib_connect'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:271:in `connect'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/connection_adapters/sqlserver_adapter.rb:59:in `initialize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/sqlserver_base.rb:18:in `new'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-sqlserver-adapter-4.2.3/lib/active_record/sqlserver_base.rb:18:in `sqlserver_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:436:in `new_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:446:in `checkout_new_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/monitor.rb:214:in `mon_synchronize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/monitor.rb:214:in `mon_synchronize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:565:in `retrieve_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/connection_handling.rb:87:in `connection'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/model_schema.rb:230:in `table_exists?'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/attribute_methods/primary_key.rb:97:in `get_primary_key'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/attribute_methods/primary_key.rb:85:in `reset_primary_key'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.0/lib/active_record/attribute_methods/primary_key.rb:73:in `primary_key'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/audited-activerecord-4.2.0/lib/audited/adapters/active_record.rb:7:in `default_ignored_attributes'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/audited-4.2.0/lib/audited/auditor.rb:48:in `audited'
from /home/david-vm/Documents/rails_projects/bane/app/models/user.rb:9:in `<class:User>'
from /home/david-vm/Documents/rails_projects/bane/app/models/user.rb:1:in `<top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:457:in `load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:457:in `block in load_file'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:647:in `new_constants_in'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:456:in `load_file'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:354:in `require_or_load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:494:in `load_missing_constant'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:184:in `const_missing'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:261:in `const_get'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:261:in `block in constantize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:259:in `each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:259:in `inject'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/inflector/methods.rb:259:in `constantize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:566:in `get'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:597:in `constantize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise.rb:377:in `get'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:81:in `to'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:76:in `modules'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:93:in `routes'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:160:in `default_used_route'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/mapping.rb:70:in `initialize'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise.rb:411:in `new'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise.rb:411:in `add_mapping'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/rails/routes.rb:241:in `block in devise_for'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/rails/routes.rb:240:in `each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/devise-4.0.1/lib/devise/rails/routes.rb:240:in `devise_for'
from /home/david-vm/Documents/rails_projects/bane/config/routes.rb:11:in `block in <top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/actionpack-4.2.0/lib/action_dispatch/routing/route_set.rb:423:in `instance_exec'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/actionpack-4.2.0/lib/action_dispatch/routing/route_set.rb:423:in `eval_block'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/actionpack-4.2.0/lib/action_dispatch/routing/route_set.rb:401:in `draw'
from /home/david-vm/Documents/rails_projects/bane/config/routes.rb:1:in `<top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `block in load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `load'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:40:in `each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:40:in `load_paths'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:16:in `reload!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:26:in `block in updater'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/file_update_checker.rb:75:in `execute'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:27:in `updater'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `instance_exec'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:30:in `run'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:55:in `block in run_initializers'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `call'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each'
from /home/david-vm/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/initializable.rb:54:in `run_initializers'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application.rb:352:in `initialize!'
from /home/david-vm/Documents/rails_projects/bane/config/environment.rb:5:in `<top (required)>'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `block in require'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:240:in `load_dependency'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:274:in `require'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/application.rb:328:in `require_environment!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:142:in `require_application_and_environment!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:67:in `console'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /home/david-vm/.rvm/gems/ruby-2.3.0/gems/railties-4.2.0/lib/rails/commands.rb:17:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'
User.rb
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :ldap_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable
after_destroy :ensure_an_admin_remains
before_create { generate_token(:auth_token) }
# Audit changes made except for the columns as specified below
audited except: [:last_seen_at, :sign_in_count, :last_sign_in_at, :last_sign_in_ip, :password_digest]
has_associated_audits
acts_as_tagger
acts_as_taggable_on :roles
# associations, methods, etc...
end
更新
原来这是一个 DNS 问题，所以即使我的 database.yml 没有改变，服务器名称也不再有效。刚刚添加了更新，以防有人遇到类似问题，可能值得一试。
答案在堆栈跟踪中。它准确地告诉您系统上的哪个文件有错误。该文件来自 gem 或位于计算机的不同部分的事实无关紧要。
/home/david-vm/.rvm/gems/ruby-2.3.0/gems/tiny_tds-0.7.0/lib/tiny_tds/client.rb:74:in `connect': Server name not found in configuration files (TinyTds::Error)
用你的编辑器打开那个文件（或者回溯中任何看起来最合适的文件），在它吹的那一行之前粘贴一个binding.pry（或者byebug，或者调试器，无论你使用什么）在 (74) 上。然后重新启动您的应用程序并进行调试，就好像它是您应用程序中的一个文件一样。