Question

I have two classes in rails 3.2.6:

• class Foo in models/foo.rb (is in table foos, per default)
• class Bar::Foo in models/bar/foo.rb (which sets self.table_name to bar_foos)

When I go into console, I get:

> Bar::Foo
=> Bar::Foo(id: ...)
> Foo # or ::Foo
LoadError: expected models/bar/foo.rb to define Foo

What’s wrong?

Answer 1

We solved this in IRC, but the core issue is that there was a config.autoload_paths glob set that was including models/** as load paths.

Rails’ auto-loader iterates the load paths, and tacks on the constant name. Once it finds a file that exists, it tries to load it, then throws an exception if the constant is not available.

So, what was happening is Rails had a list of load paths like:

/models/bar/
/models/

It was iterating the paths, and would find a match at /models/bar/foo.rb, which it then loads (which makes Bar::Foo available, but not Foo), then throws the exception because Foo isn’t available.

The solution in this case was to remove the autoload_paths setting, so that Rails would not find the wrong file to load for the root-level constant.