Advice on clearing Ecto.Date and Ecto.Time deprecations

As I’ve mentioned before I’m currently working on a project that has some gnarly deprecation issues. Being new to Elixir (and development in general) it is proving to be a great learning opportunity but I am very stuck on something.

I have a model like:

schema "person" do
 field :date_of_birth, Ecto.Date
 field :appointment_time, Ecto.Time

 timestamps()
 @required_fields ~w(appointment_time)
 @optional_fields ~w(date_of_birth)

  def changeset(model, params \\ :empty) do
    model
    |> cast(params, @required_fields, @optional_fields)
  end

date_of_birth goes to a date column in the DB and appointment_time to a time_without_timezone. appointment_time’s associated param is a string formatted like “00:00:00”.

I am utterly confused about how to replace these types properly after their deprecations. My current implementation as per my understanding of the docs:

 field :date_of_birth, :date
 field :appointment_time, :utc_datetime

This is clearly incorrect because the appointment_time fails the cast type validation. I have many examples of this particular requirement throughout the project so I’d really like to understand the correct methodology at play.