Creating mongoid relation between has_one belongs_to objects raises an error

Question

I have this relation:

class EmailType
  include Mongoid::Document
  include Mongoid::Timestamps
  has_one :job_status, :inverse_of => :email_type

class JobStatus
  include Mongoid::Document
  belongs_to :email_type, :inverse_of => :job_status

But when I try to create the relation between them I get an error. My example follows as far as I can see the same pattern as instructed on http://two.mongoid.org/docs/relations/referenced/1-1.html.

What makes this a mystery for me is that the error message displays NameError: uninitialized constant JobStatu and not NameError: uninitialized constant JobStatus...

Loading development environment (Rails 3.2.12)
2.0.0-p247 :001 > e = EmailType.new
 => #<EmailType _id: 51eafe9183c3366282000001, created_at: nil, updated_at: nil, name: nil, type: nil, value: nil, from: nil, subject: nil, line_break: "\n", order_id_line: nil, order_id_regex: nil, mail_address_line: nil, mail_address_regex: nil, name_line: nil, name_regex: nil, user_id: nil> 
2.0.0-p247 :002 > j = JobStatus.new
 => #<JobStatus _id: 51eafea583c3366282000002, group_id: nil, name: nil, status: "new", error_msg: "", extra: {}, email_type_id: nil> 
2.0.0-p247 :003 > e.job_status = j
NameError: uninitialized constant JobStatu
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/inflector/methods.rb:230:in `block in constantize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/inflector/methods.rb:229:in `each'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/inflector/methods.rb:229:in `constantize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/core_ext/string/inflections.rb:54:in `constantize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/metadata.rb:630:in `klass'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/proxy.rb:54:in `klass'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/referenced/one.rb:21:in `block in initialize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/proxy.rb:41:in `init'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/referenced/one.rb:20:in `initialize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:44:in `new'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:44:in `create_relation'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:26:in `__build__'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:269:in `block (2 levels) in setter'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:175:in `without_autobuild'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:263:in `block in setter'
from (irb):3
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/railties-3.2.12/lib/rails/commands/console.rb:47:in `start'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/railties-3.2.12/lib/rails/commands/console.rb:8:in `start'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/railties-3.2.12/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'2.0.0-p247 :004 > 

Just to be sure that I haven't mixed it up I have tried to do it the other way round:

Loading development environment (Rails 3.2.12)
2.0.0-p247 :001 > e = EmailType.new
 => #<EmailType _id: 51eaff9283c3365840000001, created_at: nil, updated_at: nil, name: nil, type: nil, value: nil, from: nil, subject: nil, line_break: "\n", order_id_line: nil, order_id_regex: nil, mail_address_line: nil, mail_address_regex: nil, name_line: nil, name_regex: nil, user_id: nil> 
2.0.0-p247 :002 > j = JobStatus.new
 => #<JobStatus _id: 51eaff9483c3365840000002, group_id: nil, name: nil, status: "new", error_msg: "", extra: {}, email_type_id: nil> 
2.0.0-p247 :003 > j.email_type = e
NameError: uninitialized constant JobStatu
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/inflector/methods.rb:230:in `block in constantize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/inflector/methods.rb:229:in `each'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/inflector/methods.rb:229:in `constantize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-3.2.12/lib/active_support/core_ext/string/inflections.rb:54:in `constantize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/metadata.rb:630:in `klass'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/proxy.rb:54:in `klass'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/referenced/one.rb:21:in `block in initialize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/proxy.rb:41:in `init'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/referenced/one.rb:20:in `initialize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:44:in `new'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:44:in `create_relation'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:26:in `__build__'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:269:in `block (2 levels) in setter'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:175:in `without_autobuild'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:263:in `block in setter'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/extensions/object.rb:104:in `do_or_do_not'
... 5 levels...
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/proxy.rb:25:in `bind_one'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/referenced/in.rb:25:in `block in initialize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/proxy.rb:41:in `init'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/referenced/in.rb:23:in `initialize'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:44:in `new'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:44:in `create_relation'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:26:in `__build__'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:269:in `block (2 levels) in setter'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:175:in `without_autobuild'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/mongoid-3.1.3/lib/mongoid/relations/accessors.rb:263:in `block in setter'
from (irb):3
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/railties-3.2.12/lib/rails/commands/console.rb:47:in `start'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/railties-3.2.12/lib/rails/commands/console.rb:8:in `start'
from /Users/christoffer-jorgensen/.rvm/gems/ruby-2.0.0-p247/gems/railties-3.2.12/lib/rails/commands.rb:41:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'2.0.0-p247 :004 >

Answer 1

Shorter solution:

has_one :job_status, :inverse_of => :email_type, :class_name => "JobStatus"

UPDATE:

@Ophion: I meant this should work:

class EmailType
  include Mongoid::Document
  include Mongoid::Timestamps
  has_one :job_status, :inverse_of => :email_type, :class_name => "JobStatus"

Explicitly add the class_name to the relationship so Mongoid will use it directly without having to singularize to get the Model name.

Answer 2

You're using ruby 2.0, and I don't have anything to check it with, but to help you, try a simpler name, likely something without an S in the end. Statu instead of Status means that mongoid tries to make it singluar, when searching for an specific model.

Your model sounds alright and you should be able to do it in reverse, so try e.job_status = j, and see if it truly works.

Answer 3

It is a well-known Mongoid problem, described here in the official documentation

One possible workaround would be doing as suggested in the aforementioned document:

ActiveSupport::Inflector.inflections do |inflect|
  inflect.singular("jobstatus", "jobstatus")
end

Or something close to that.