How to fix? ( undefined method name' for nil:NilClass ) about rails-erd

[rolftimmermans]

Thanks for your report. Could you include your database schema and ActiveRecord models? If you don't wont to post it here, you can email it to me as well.

[ldonnet]

I have the same issue with my models :

undefined method `name' for nil:NilClass
/home/luc/.rbenv/versions/1.8.7-debian/gems/gems/rails-erd-1.1.0/lib/rails_erd/domain/specialization.rb:70:in `<=>'
/home/luc/.rbenv/versions/1.8.7-debian/gems/gems/rails-erd-1.1.0/lib/rails_erd/domain/specialization.rb:13:in `sort'
/home/luc/.rbenv/versions/1.8.7-debian/gems/gems/rails-erd-1.1.0/lib/rails_erd/domain/specialization.rb:13:in `from_models'

I add some log in my file and I see this :

#<RailsERD::Domain::Entity:0x007f5c0b8096e8 @model=Chouette::ActiveRecord>
#<RailsERD::Domain::Entity:0x007f5c0b8096e8 @model=Chouette::ActiveRecord>
#<RailsERD::Domain::Entity:0x007f5c0b808f68 @model=Chouette::TridentActiveRecord>
nil

for this code :

def <=>(other) # @private :nodoc:
    puts generalized.inspect
    puts other.generalized.inspect
    puts specialized.inspect
    puts other.specialized.inspect
        (generalized.name <=> other.generalized.name).nonzero? or (specialized.name <=> other.specialized.name)
      end

And my class Chouette::TridentActiveRecord is an abstract class.

class Chouette::TridentActiveRecord < Chouette::ActiveRecord
end

module Chouette
  class ActiveRecord < ::ActiveRecord::Base
  end
end

Perhaps we need to test if generalized and specialized present?

[skydan]

Same issue for me:

Generating Entity-Relationship Diagram for 51 models...
Warning: Ignoring invalid association :tagger on ActsAsTaggableOn::Tagging (polymorphic interface Tagger does not exist)
Warning: Ignoring invalid association :resource on ActiveAdmin::Comment (polymorphic interface Resource does not exist)
Warning: Ignoring invalid association :author on ActiveAdmin::Comment (polymorphic interface Author does not exist)
Warning: Ignoring invalid association :owner on PublicActivity::Activity (polymorphic interface Owner does not exist)
Warning: Ignoring invalid association :recipient on PublicActivity::Activity (polymorphic interface Recipient does not exist)
Warning: Ignoring invalid association :ratings on User (uninitialized constant User::Rating)
Warning: Ignoring invalid association :ratings on User (uninitialized constant User::Rating)
Warning: Ignoring invalid association :ratings on User (uninitialized constant User::Rating)
Warning: Ignoring invalid association :parents_wait_list on Program (Could not find the source association(s) :parents_wait_list or :parents_wait_list in model ProgramParentOrderRelation. Try 'has_many :parents_wait_list, :through => :program_parent_order_relations, :source => <name>'. Is it one of :activities, :program, :line_item, or :parent?)
rake aborted!
undefined method `name' for nil:NilClass
/Users/skydan/.rvm/gems/ruby-1.9.3-p448@global/gems/rails-erd-1.1.0/lib/rails_erd/domain.rb:111:in `block (2 levels) in specializations_mapping'
/Users/skydan/.rvm/gems/ruby-1.9.3-p448@global/gems/rails-erd-1.1.0/lib/rails_erd/domain.rb:109:in `each'
/Users/skydan/.rvm/gems/ruby-1.9.3-p448@global/gems/rails-erd-1.1.0/lib/rails_erd/domain.rb:109:in `block in specializations_mapping'
/Users/skydan/.rvm/gems/ruby-1.9.3-p448@global/gems/rails-erd-1.1.0/lib/rails_erd/domain.rb:108:in `tap'
/Users/skydan/.rvm/gems/ruby-1.9.3-p448@global/gems/rails-erd-1.1.0/lib/rails_erd/domain.rb:108:in `specializations_mapping'
/Users/skydan/.rvm/gems/ruby-1.9.3-p448@global/gems/rails-erd-1.1.0/lib/rails_erd/domain.rb:81:in `specializations_by_entity_name'
/Users/skydan/.rvm/gems/ruby-1.9.3-p448@global/gems/rails-erd-1.1.0/lib/rails_erd/domain/entity.rb:92:in `children'

[amccloud]

Same here

undefined method `name' for nil:NilClass
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/domain/specialization.rb:66:in `<=>'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/domain/specialization.rb:13:in `sort'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/domain/specialization.rb:13:in `from_models'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/domain.rb:67:in `specializations'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/diagram.rb:170:in `filtered_specializations'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/diagram.rb:132:in `generate'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/diagram.rb:119:in `create'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/diagram.rb:74:in `create'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rails-erd-1.1.0/lib/rails_erd/tasks.rake:41:in `block (2 levels) in <top (required)>'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:236:in `call'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:236:in `block in execute'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:231:in `each'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:231:in `execute'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:175:in `block in invoke_with_call_chain'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:168:in `invoke_with_call_chain'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:197:in `block in invoke_prerequisites'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:195:in `each'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:195:in `invoke_prerequisites'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:174:in `block in invoke_with_call_chain'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:168:in `invoke_with_call_chain'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/task.rb:161:in `invoke'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:149:in `invoke_task'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:106:in `each'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:106:in `block in top_level'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:115:in `run_with_threads'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:100:in `top_level'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:78:in `block in run'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:165:in `standard_exception_handling'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/lib/rake/application.rb:75:in `run'
/srv/www/example/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/rake-10.1.0/bin/rake:33:in `<top (required)>'
/srv/www/example/.rbenv/versions/2.0.0-p247/bin/rake:23:in `load'
/srv/www/example/.rbenv/versions/2.0.0-p247/bin/rake:23:in `<main>'
Tasks: TOP => erd => erd:generate

[rzane]

I encountered the same issue. It does seem to be related to abstract classes, because that's what went wrong for me. I have two abstract classes in my application.

I changed the <=> method to this, so I could find out where the sort went wrong:

def <=>(other) # @private :nodoc:
  (generalized.name <=> other.generalized.name).nonzero? or (specialized.name <=> other.specialized.name)
rescue
  raise other.inspect
end

Once I found out which class it was, I added this to it, and everything worked fine:

def self.table_exists?
  true
end

It's kind of strange, especially because I only added the table_exists? to one of my two classes.

[codez]

The following patch helped in my case. ERD removed the non-abstract models because it could not connect to their database, but used them again in the Specialization class. The patch makes sure that an entity really exists in the list before creating a specialization for it.

module RailsERD
  class Domain
    class Specialization
      class << self
        def abstract_from_models(domain, models)
          models.select(&:abstract_class?).
                 collect(&:descendants).
                 flatten.
                 select  { |model| domain.entity_by_name(model.name) }.
                 collect { |model|
            new(domain, domain.entity_by_name(model.superclass.name), domain.entity_by_name(model.name))
          }
        end
      end
    end
  end
end

[pcdoc80]

@codez: Which file did you put that code in?

[codez]

To fix the issue permanently, this method should be replaced in Rails ERD in lib/rails_erd/domain/specialization.rb.

To fix temporarly in my application, I require it in a rake task that is run before the erd task:

namespace :erd do
  task :options => :customize
  task :customize do
    require 'rails_erd/domain/specialization'
    require Rails.root.join('lib', 'tasks', 'erd_patch.rb')  # this is where above patch resides
  end
end

[bf4]

PR?

[kerrizor]

I just pushed a fix for this that uses a NullObject pattern to patch around the error. This should be fixed now; I'll push a new version of the gem (1.2.2) later on this evening.

[ldonnet]

Thanks for this patch

[vaibhav8186]

@kerrizor @codez This issue still exists in rails-erd (1.6.0). So can you please give your thoughts on that.

[pooja-mane]

@kerrizor @codez @rolftimmermans I am also facing the same issue as
NoMethodError: undefined method name' for nil:NilClass`
rails-erd(1.6.0)

[karamat]

I have fixed this issue temporarily and successfully generate ERD diagram. 2 things I have done.

1- Tracing back to the point of crash, and found that it is happening due to relationship.destination nil . So I handled nil check by searching this in all the code

2- After this it crashed again in this method in /lib/rails-erd/domain/relationship.rb

def foreign_key_required?(association)
  if !association.active_record.abstract_class? and association.belongs_to?
    column = association.active_record.columns_hash[association.send(Domain.foreign_key_method_name)] and !column.null
  end
end

I rescued the line that was crashing

def foreign_key_required?(association)
  if !association.active_record.abstract_class? and association.belongs_to?
    begin
      column = association.active_record.columns_hash[association.send(Domain.foreign_key_method_name)] and !column.null
    rescue Exception => e
      p e.message
    end
  end
end

Hope this helps someone