TypeError: allocator undefined for Proc when working with a model object in a Rails 3.2 project

Question

When I work with object of type Staffer, which inherits User which inherits ActiveRecord::Base I get the error "TypeError: allocator undefined for Proc".

I'm not sure what caused it to start happening and unfortunately it won't be easy to track down the commit that did. Since the system was working properly, user.rb didn't change and staffer.rb only change one line to remove an unused constant.

I first noticed the error when running a rake task and the error is generated from a line that does this:

attributes.slice("id", "email", "state")

further investigation showed that this triggers the error too:

puts attributes

and this is the backtrace:

rake aborted!
allocator undefined for Proc
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:227:in `allocate'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:227:in `revive'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:183:in `visit_Psych_Nodes_Mapping'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/delayed_job-3.0.1/lib/delayed/psych_ext.rb:119:in `visit_Psych_Nodes_Mapping_with_class'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:7:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `block in revive'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `map'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `revive'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:183:in `visit_Psych_Nodes_Mapping'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/delayed_job-3.0.1/lib/delayed/psych_ext.rb:119:in `visit_Psych_Nodes_Mapping_with_class'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:7:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:116:in `block in visit_Psych_Nodes_Sequence'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:116:in `each'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:116:in `visit_Psych_Nodes_Sequence'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:8:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `block in revive'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `map'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `revive'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:183:in `visit_Psych_Nodes_Mapping'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/delayed_job-3.0.1/lib/delayed/psych_ext.rb:119:in `visit_Psych_Nodes_Mapping_with_class'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:7:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `block in revive'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `map'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `revive'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:183:in `visit_Psych_Nodes_Mapping'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/delayed_job-3.0.1/lib/delayed/psych_ext.rb:119:in `visit_Psych_Nodes_Mapping_with_class'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:7:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:191:in `block in visit_Psych_Nodes_Mapping'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:190:in `each'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:190:in `each_slice'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:190:in `visit_Psych_Nodes_Mapping'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/delayed_job-3.0.1/lib/delayed/psych_ext.rb:119:in `visit_Psych_Nodes_Mapping_with_class'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:7:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/nodes/node.rb:25:in `to_ruby'
/Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych.rb:107:in `load'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/coders/yaml_column.rb:25:in `load'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/serialization.rb:24:in `unserialize'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/serialization.rb:15:in `unserialized_value'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/read.rb:82:in `__temp__'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/read.rb:46:in `type_cast_attribute'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/read.rb:126:in `read_attribute'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods.rb:183:in `block in attributes'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods.rb:183:in `each'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods.rb:183:in `map'
/Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods.rb:183:in `attributes'
/Users/pupeno/Documents/watu/app/models/staffer.rb:151:in `index'

Trying to figure out what was going on, I opened a rails console and just got the first staffer, to encounter the same error:

1.9.2-p290 :019 > s = Staffer.first
  Staffer Load (3.8ms)  SELECT "users".* FROM "users" WHERE "users"."type" IN ('Staffer') LIMIT 1
TypeError: allocator undefined for Proc
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:227:in `allocate'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:227:in `revive'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:183:in `visit_Psych_Nodes_Mapping'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/delayed_job-3.0.1/lib/delayed/psych_ext.rb:119:in `visit_Psych_Nodes_Mapping_with_class'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:7:in `accept'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `block in revive'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `map'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:228:in `revive'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:183:in `visit_Psych_Nodes_Mapping'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/delayed_job-3.0.1/lib/delayed/psych_ext.rb:119:in `visit_Psych_Nodes_Mapping_with_class'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/visitor.rb:7:in `accept'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:16:in `accept'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:116:in `block in visit_Psych_Nodes_Sequence'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:116:in `each'
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:116:in `visit_Psych_Nodes_Sequence'
... 24 levels...
    from /Users/pupeno/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych.rb:107:in `load'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/coders/yaml_column.rb:25:in `load'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/serialization.rb:24:in `unserialize'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/serialization.rb:15:in `unserialized_value'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/read.rb:82:in `__temp__'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/read.rb:46:in `type_cast_attribute'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods/read.rb:126:in `read_attribute'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/attribute_methods.rb:200:in `attribute_for_inspect'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/base.rb:640:in `block in inspect'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/base.rb:638:in `collect'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/activerecord-3.2.2/lib/active_record/base.rb:638:in `inspect'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/railties-3.2.2/lib/rails/commands/console.rb:47:in `start'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/railties-3.2.2/lib/rails/commands/console.rb:8:in `start'
    from /Users/pupeno/.rvm/gems/ruby-1.9.2-p290@watu/gems/railties-3.2.2/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'
1.9.2-p290 :020 >

Answer 1

Do you have any yaml-serialized data in one of your staffer/user fields?

If so I think it has to do with the serialized data not with your code. Check to see if in your serialized data there's a serialized Proc object or so... That should be the reason why it can't load, cause somehow Procs can't be serialized!?

See this forum post.