We moved this file to `app/lib/` in commit cb477149c so it would be in
the autoload_paths. However, this class is loaded by ActiveStorage, with
the following method:
```
def resolve(class_name)
require "active_storage/service/#{class_name.to_s.underscore}_service"
ActiveStorage::Service.const_get(:"#{class_name.camelize}Service")
rescue LoadError
raise "Missing service adapter for #{class_name.inspect}"
end
``
So this file needs to be in the $LOAD_PATH, or else ActiveStorage won't
be able to load it when we disable the `add_autoload_paths_to_load_path`
option, which is the default in Rails 7.1 [1].
Moving it to the `lib` folder solves the issue; as mentioned in the
guide to upgrade to Rails 7.1 [2]:
> The lib directory is not affected by this flag, it is added to
> $LOAD_PATH always.
However, we were also referencing this class in the `Tenant` model,
meaning we needed to autoload it as well somehow. So, instead of
directly referencing this class, we're using `respond_to?` in the Tenant
model.
We're changing the test so it fails when the code calls
`is_a?(ActiveStorage::Service::TenantDiskService)`. We need to change
the active storage configurations in the test because, otherwise, the
moment `ActiveStorage::Blob` is loaded, the `TenantDiskService` class is
also loaded, meaning the test will pass when using `is_a?`.
Note that, since this class isn't in the autoload paths anymore, we need
to add a `require` in the tests. We could add an initializer to require
it; we're not doing it in order to be consistent with what ActiveStorage
does: it only loads the service that's going to be used in the current
Rails environment. If somebody changed their production environment in
order to use (for example), S3, and we added an initializer to require
the TenantDiskService, we would still load the TenantDiskService even if
it isn't going to be used.
[1] https://guides.rubyonrails.org/v7.1/configuring.html#config-add-autoload-paths-to-load-path
[2] https://guides.rubyonrails.org/v7.1/upgrading_ruby_on_rails.html#autoloaded-paths-are-no-longer-in-$load-path
The purpose of the lib folder is to have code that doesn't necessary
belong in the application but can be shared with other applications.
However, we don't have other applications and, if we did, the way to
share code between them would be using a gem or even a git submodule.
So having both the `app/` and the `lib/` folders is confusing IMHO, and
it causes unnecessary problems with autoloading.
So we're moving the `lib/` folder to `app/lib/`. Originally, some of
these files were in the `app/services/` folder and then they were moved
to the `lib/` folder. We're using `app/lib/` instead of `app/services/`
so the upgrade is less confusing.
There's an exception, though. The `OmniAuth::Strategies::Wordpress`
class needs to be available in the Devise initializer. Since this is an
initializer and trying to autoload a class here will be problematic when
switching to Zeitwerk, we'll keep the `require` clause on top of the
Devise initializer in order to load the file and so it will be loaded
even if it isn't in the autoload paths anymore.
We were using the same logic in many different places, so we're
simplifying the code. I'm not convinced about the method names, though,
so we might change them in the future.
Note using this method for the default tenant in the `TenantDiskService`
class resulted in a `//` in the path, which is probably harmless but
very ugly and it also generates a different key than the one we got
until now. I've added an extra test to make sure that isn't the case.
While this is not strictly necessary, it can help moving the data of one
tenant to a different server or removing it.
Note we're using subfolders inside the `tenants` subfolder. If we simply
used subfolders with the schema names, if the schema names were, for
instance, language codes like `es`, `en`, `it`, ... they would conflict
with the default subfolders used by Active Storage.
