NameError uninitialized constant rails

Question

I have a simple model called PhoneNumber   class PhoneNumber  lt  ActiveRecord  Base   validates  pnumber  presence  true  on   create    gt     message   gt    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  gt  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   lt top  required  gt   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   lt top  required  gt   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   lt top  required  gt   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   lt main gt   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

User · Answer

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

User · Answer

I had the same error  Turns out in my hasty scaffolding I left out the model rb file

User · Answer

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  gt  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

User · Answer

Similar with  Michael-Neal   I had named the controller as singular  app controllers product controller rb  When I renamed it as plural  error solved  app controllers products controller rb

User · Answer

I started having this issue after upgrading from Rails 5 1 to 5 2 It got solved with   spring stop spring binstub --all spring start rails s

User · Answer

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

User · Answer

I had this problem because I changed the name of the class in a model  and it did not match the name of the file    Model class names use CamelCase  These are singular  and will map automatically to the plural database table name   Model files go in app models   singular model name  rb    https   gist github com iangreenleaf b206d09c587e8fc6399e model

User · Answer

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

User · Answer

In my case  I named a column name type and tried to set its value as UNPREPARED  And I got an error message like this      Caused by    api 1    NameError  uninitialized constant UNPREPARED   In rails  column type is reserved      ActiveRecord  SubclassNotFound  The single-table inheritance mechanism failed to locate the subclass   UNPREPARED   This error is raised because the column  type  is reserved for storing the class in case of inheritance  Pl   ease rename this column if you didn t intend it to be used for storing the inheritance class or overwrite Food inheritance column to use another column for that information

User · Answer

I had a similar error  but it was because I had created a has one relationship and subsequently deleted the model that it had one of  I just forgot to delete the has one relationship from the remaining model

[ruby-on-rails-4] NameError: uninitialized constant (rails)

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