Rails: NameError: uninitialized constant
Solution 1
Some things to try:
Restart the rails console; changes to your models will only get picked up by a rails console that is already open if you do
> reload!
(although I have found this to be unpredictable), or by restarting the console.Is your model file called "phone_number.rb" and is it in "/app/models"?
You should double-check the "--sandbox" option on your rails console command. AFAIK, this prevents changes. Try it without the switch.
Solution 2
I was getting the error:
NameError: uninitialized constant
Then I noticed that I had accidentally created a plural model so I went back and renamed the model file to singular and also changed the class name in the model file to singular and that solved it.
Solution 3
I started having this issue after upgrading Rails 5.1 to 5.2
I got it solved with:
spring stop
spring binstub --all
spring start
rails s
Solution 4
I ran into this also with a file directly in the models
directory, and it turns out that I wasn't properly loading up the code on startup. I was able to fix the issue by setting config.eager_load = true
in my development.rb file. This made the class available to me in the console
Solution 5
If none of the above work, I also have a different approach, as it happened to me in a real scenario.
More specifically using auto-generated Ruby files from Thrift.
In my situation, I had a Module
with several classes, so the order is important in this case:
Class A
makes use of Class B
in the same module. However, Class B
was declared after Class A
.
Simply making Class B
to be declared before Class A
solved the issue to me.
Comments
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Nick stands with Ukraine almost 3 years
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?
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Nick stands with Ukraine over 9 yearsIt 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.
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lostphilosopher over 7 yearsHere's more information on this solution: collectiveidea.com/blog/archives/2016/07/22/… tldr; "With Rails 5, autoloading is now completely disabled if config.eager_load = true."
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Meekohi almost 7 years
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. -
ferne97 about 4 yearsThank you! Wasted hours on this.
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Olivier JM about 4 yearsIn my case the model was named in plural I just had to change that. Thank you
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ispirett over 2 yearsYes this is important.
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Indika K about 2 yearsMy problem was solved by restarting the rails console.