rails hash.as_json method producing unexpected result with boolean value

Question

Ruby on Rails adds the "as_json" method to many common classes, which turns ActiveRecord objects into hash objects that can then be sent to a JSON serializer. Recently I encountered a bug in my code related to this method and it's treatment of boolean values.

I can summarize the bug very concisely:

{"foo" => true}.as_json

I would expect this method to return an identical hash. Instead, it returns

{"foo" => "true"}

This appears to be by design, as per line 157 in encoding.rb

AS_JSON = ActiveSupport::JSON::Variable.new('true').freeze

Can I ask, why is rails returning the string value "true" instead of keeping it as a true boolean value?

My bug is as follows: I keep JSON-serialized objects in a cache. When I pull them out of the cache I leave them as hashes to avoid unnecessary object deserialization. If I don't find it in the cache, I pull the object out of the database and call as_json on it. I expect what I pull out of the cache and what I get back from as_json to be identical. They're not, because what comes out of the cache is {"foo" => true} and what comes back from as_json is {"foo" => "true"}

apneadiving · Accepted Answer · 2011-07-03 19:37:29Z

1

That's the way it's implemented.

You could change the default behavior putting this in an initializer:

class TrueClass
  def as_json(*options)
    self
  end
end

class FalseClass
  def as_json(*options)
    self
  end
end

answered Jul 3, 2011 at 19:37

apneadiving

116k26 gold badges225 silver badges215 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

esilver Over a year ago

Right, I know that is how it is implemented, but not knowing the justification I am wary of changing its behavior lest I break another component.

apneadiving Over a year ago

I don't think there is any json exchange within Rails so you shoudn't fear this.

Collectives™ on Stack Overflow

rails hash.as_json method producing unexpected result with boolean value

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related