问题
I upgraded Rails from version 3.1.2 (which worked fine) to 4.0, and got stuck with the following error:
circular dependency detected while autoloading constant Foo
I created a class ProductFactory, where I instantiate different models. For example:
p = Foo.new(params)
The model "Foo" is not always an ActiveRecord. Could anyone help me with this issue?
回答1:
This kind of issues often happen when you change the version of Rails. You maybe didnt update the gems on the right order.
回答2:
Best I'm aware, circular dependencies error messages usually occur when cascading includes go wrong by recursively requiring a file before it is fully loaded, e.g.:
# File A:
require 'B'
module Foo; end
# File B:
require 'A'
module Foo; end
Any odds this is the kind of situation you're ending up with?
回答3:
I had this error because I manually renamed controllers, routes etc etc and forgot to rename it in the first line of the files.
Was named
class AController < ApplicationController
instead of
class ARenamedController < ApplicationController
and I had gone and renamed all the other files individuall.
Not best practice I know, but I am learning and figuring it out, and in this case created the error this person is talking about. So if you got here through Google like I did, there is my solution.
来源：https://stackoverflow.com/questions/18921079/circular-dependency-detected-while-autoloading-a-constant