Question

When I call to_json on my Factory Girl object, I get a nil.[] error.

I’m using DataMapper on Rails 3, and when I call to_json on a real DataMapper object, it works just fine. Any idea why the Factory Girl object is failing?

Factory.define :something do |b|
  b.date_foo { 3.days.ago - 4.hours }
  b.date_bar { 3.days.ago - 4.hours }
  b.somestring '11'
  b.anotherstring 'ASTRINGYAY'
  b.thirdstring 'STRINGG'
  b.fourthstring 'STRING'
  b.otherstring 'thestring'
  b.longerstring 'The string that is longer'
  b.somenumber 3
  b.someothernumber 2
  b.an_id 5593
  b.a_version '1.2.2.2'
  b.a_string '1.2.2.2'
  b.something '1.2.2.2'
  b.code 'SOME CODE'
  b.other_code 'API'
  b.something_id 49
  b.something_version 'OMG'
  b.otherthing 'N/A'
  b.lastthing 'A'
end

Also, I discovered the following:

factory_girl_object.to_json works fine.

[factory_girl_object].to_json fails.

DataMapper apparently uses DataMapper::Collection objects instead of arrays, which handle to_json a bit different for it’s contents than arrays do. I can’t seem to figure out how to create a DataMapper::Collection object to hold my Factory_Girl objects, however.

Thoughts?

Answer 1

Ha, might as well come back and answer this.

DataMapper serves objects in a specialized array-like data structure that handles JSON serialization for you. If you try to put DM objects in a regular array, it fails horribly, spawning the errors I mentioned above.