undefined method `[]' for nil:NilClass when using as_json

[jwoertink]

I have a simple Photo model

class Photo
  include Mongoid::Document
  mount_uploader :photo_image, PhotoUploader

  belongs_to :attachable, polymorphic: true
end

My photos upload and save fine, but when I call as_json I get an undefined method [] for nil class.

1.9.3p362 :009 > Photo.first.as_json
NoMethodError: undefined method `[]' for nil:NilClass
    from /Users/jeremy/.rvm/gems/ruby-1.9.3-p362@tabeso/gems/carrierwave-mongoid-0.3.0/lib/carrierwave/mongoid.rb:67:in `block in serializable_hash'
    from /Users/jeremy/.rvm/gems/ruby-1.9.3-p362@tabeso/gems/carrierwave-mongoid-0.3.0/lib/carrierwave/mongoid.rb:66:in `each'
    from /Users/jeremy/.rvm/gems/ruby-1.9.3-p362@tabeso/gems/carrierwave-mongoid-0.3.0/lib/carrierwave/mongoid.rb:66:in `serializable_hash'
    from /Users/jeremy/.rvm/gems/ruby-1.9.3-p362@tabeso/gems/activemodel-3.2.11/lib/active_model/serializers/json.rb:96:in `as_json'
    from (irb):9
    from /Users/jeremy/.rvm/gems/ruby-1.9.3-p362@tabeso/gems/railties-3.2.11/lib/rails/commands/console.rb:47:in `start'
    from /Users/jeremy/.rvm/gems/ruby-1.9.3-p362@tabeso/gems/railties-3.2.11/lib/rails/commands/console.rb:8:in `start'
    from /Users/jeremy/.rvm/gems/ruby-1.9.3-p362@tabeso/gems/railties-3.2.11/lib/rails/commands.rb:41:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

Now, if I pass an empty hash, it works.

1.9.3p362 :010 > Photo.first.as_json({})
 => {"_id"=>"50f5d85fd86367cc3c000001", "attachable_field"=>nil, "attachable_id"=>"50f49d74d863677939000134", "attachable_type"=>"Event", "photo_image"=>{"url"=>"", :thumb=>{"url"=>""}}, "primary"=>true, "url"=>nil}

I think just changing the default argument in this method from nil to {} should fix it.
https://github.com/jnicklas/carrierwave-mongoid/blob/master/lib/carrierwave/mongoid.rb#L64

[rmm5t]

This should have been fixed in #81. Instead of v0.3.0, please try carrierwave-mongoid 0.3.1 or 0.4.0.

Let me know if that does the trick.

[rmm5t]

@jwoertink Was this resolved for you in carrierwave-mongoid 0.3.1?

[jwoertink]

@rmm5t yeah, that works! thanks! Looks like I'm good now, so I'll close this out.