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exception_class.to_json == "{\"inheritable_attributes\":{}}"

#3622

The way to_json treats classes is strange, and new in 2.3 (this worked as expected in 2.2):

StandardError.to_json == "{\"inheritable_attributes\":{}}"
StandardError.to_s == "StandardError"

However:

irb(main):001:0> require 'json'
=> true
irb(main):002:0> StandardError.to_json
=> "\"StandardError\""
irb(main):003:0> StandardError.to_s
=> "StandardError"

Reported by Greg Hazel · December 27th, 2009 @ 07:24 AM

Activity

Prem Sichanugrist (sikachu)
- State changed from new to wontfix
- Importance changed from to Low
Hi,

From your report, I think you are suggesting that Rails' to_json should have the same outcome as pure irb, right?

I can confirm the above outcome on Rails 3.0.1. However, I don't think this is a bug, as this is the way Rails make sure that everything can be converted to JSON. Calling to_json on an object would actually calling to_hash or returning instance_values if it doesn't implements to_hash. Unintentionally, StandardError doesn't implements to_hash, and so you got the instance variables (or class variables, in this case) instead.

October 17th, 2010 @ 05:09 PM
Prem Sichanugrist (sikachu)
One more thing,

and you saw inheritable_attributes in the list of attributes because that's actually a hash storing the list of class's inheritable attributes.

October 17th, 2010 @ 05:11 PM
Greg Hazel
Why should Rails to_json work any differently than regular to_json for non-Rails objects?

Also, as you can see from Marshal, there is no need to dump anything about inheritable_attributes in order to instantiate StandardError again.
```
>> Marshal.dump(StandardError)
=> "\004\bc\022StandardError"
>> Marshal.load(Marshal.dump(StandardError))
=> StandardError
```
October 18th, 2010 @ 12:16 AM