Rails: NameError: uninitialized constant

发布于 2014-10-15 22:51:07

I have a simple model called PhoneNumber:

class PhoneNumber < ActiveRecord::Base
  validates :pnumber, presence: true, on: :create #=> { :message => " cannot be blank" }
  validates :pnumber, numericality: true, on: :create
end

I go to the root folder of the application (the one containing the app sub-folder) and start the console:

rails console --sandbox

When I try to create an empty PhoneNumber (I want to get an error message as the validation shall fail) I am getting the following error message:

2.0.0-p451 :001 > PhoneNumber.new
NameError: uninitialized constant PhoneNumber
from (irb):1
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/commands/console.rb:90:in `start'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/commands/console.rb:9:in `start'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/commands/commands_tasks.rb:69:in `console'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/commands.rb:17:in `<top (required)>'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/app_rails_loader.rb:43:in `require'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/app_rails_loader.rb:43:in `block in exec_app_rails'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/app_rails_loader.rb:32:in `loop'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/app_rails_loader.rb:32:in `exec_app_rails'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/lib/rails/cli.rb:5:in `<top (required)>'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/bin/rails:9:in `require'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/gems/railties-4.1.5/bin/rails:9:in `<top (required)>'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/bin/rails:23:in `load'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/bin/rails:23:in `<main>'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/bin/ruby_executable_hooks:15:in `eval'
from /Users/nnikolo/.rvm/gems/ruby-2.0.0-p451@railstutorial_rails_4_0/bin/2.2.2.02.02.02.0.2.2.02.222222.2.02.02.0.2.2.022222222222222

It seems the console is not aware of the model. In plain ruby you need to 'require' the file containing the class but I thought that the rails console shall automatically load all models. What is going on here?

Questioner

Nick

Viewed

Original

Nick 2014-10-16 01:06:14

It seems it was the name of the file - it was app/models/PhoneNumber.rb. When I changed it to app/models/phone_number.rb the error message disappeared.

Meekohi 2017-05-16 18:34:31

reload! worked for me! Seems like some parts of the model initialization get cached, so if there is an error in that section it can become an "invisibile" error when you run the console a second time.

Olivier JM 2020-03-13 12:20:07

In my case the model was named in plural I just had to change that. Thank you

Rails: NameError: uninitialized constant

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