Question

I have created some classes in a module, f.i. Request (app/models/api/request.rb)

class Api::Request
end

And now I want to check in the console does the class exist?

>> Api.const_defined?('Request')
=> false
>> Api::Request
=> Api::Request
>> Api.const_defined?('Request')
=> true

Strange, but the script cannot see the class name unless I use it in the code.
How to fix this? And if you can explain the issue, it will be great.
The project uses Rails 2.3

Answer 1

The problem here is with the rails autoload mechanism. Basically what it does is to react to the method const_missing which you can define on every object. When this method is called, Rails looks for a file which is likely to contain a definition for the missing constant and requires it. The problem is that

Api::Request

triggers const_missing but

Api.const_defined?('Request')

does not.

You can write your own const_defined? like this (the code would go into a rails initializer):

def Module.autoload_const_defined?(name)
  self.const_get name
ensure
  return self.const_defined?(name)
end

which first tries to autoload the constant.