As of Ruby 2.2, Psych can handle any object which is marshallable. This
was not true on previous versions of Ruby, so our delegator types had to
provide their own implementation of `init_with` and `encode_with`.
Unfortunately, this doesn't match up with what Psych will do today.
Since by the time we hit this layer, the objects will have already been
created, I think it makes the most sense to just grab the current type
from the class.
I should have done this in the first place. We are now serializing an
explicit version so we can make more careful changes in the future. This
will load Active Record objects which were serialized in Rails 4.1.
There will be bugs, as YAML serialization was at least partially broken
back then. There will also be edge cases that we might not be able to
handle, especially if the type of a column has changed.
In addition, we're passing this as `from_database`, since that is
required for serialized columns at minimum. All other types were
serializing the cast value. At a glance, there should be no types for
which this is a problem.
Finally, dirty checking information will be lost on records serialized
in 4.1, so no columns will be marked as changed.
While running the spec `ARCONN=mysql2 ruby -v -Itest
test/cases/yaml_serialization_test.rb`
the following warning shows up:
`implementing to_yaml is deprecated, please implement "encode_with"`
During `init_with`, the attributes given to the coder will be placed
into `@raw_attributes`. As such, we should read from `@raw_attributes`
when encoding, rather than `@attributes`, which has been type cast.
