GlobalID assumes model name exists as constant in the top-level namespace

[bdragon]

Currently GlobalID assumes that the GID model name exists as a constant defined in the top-level namespace. This is fine as a default, but I should be able to lookup models however I want if I'm using a customer locator.

Real world use case:

I have a monolithic application that I plan to break up into smaller services in the future. We are experimenting with GIDs to facilitate that transition.

Most GIDs look like 'gid://my-app/Person/1'.

For resources in namespaced modules that will eventually be refactored out, GIDs look like 'gid://my-module/Customer/1'. I have defined a custom locator for each module to handle this:

GlobalID::Locator.use :'my-module', MyModuleLocator.new

class MyModuleLocator
  def locate(gid)
    MyModule.const_get(gid.model_name).find(gid.model_id)
  end
end

However, this does not work—GlobalID.find('gid://my-module/Customer/1') raises a LoadError.

This is because GlobalID::Locator::find invokes GlobalID#model_class (which tries to Object.cont_get() the model name) before my custom locator is ever invoked [1]. Of course this raises a LoadError, because 'Customer' lives in the MyModule namespace.

[1] https://github.com/rails/globalid/blob/v0.3.6/lib/global_id/locator.rb#L17

[jeremy]

Ideally, a custom locator could manage model class loading as you expect. Could you work up a pull request to implement?

[jeremy]

Stalled out.