Email format validation helper text

email_format_validation.ex

defmodule MyApp.Blog.Author do
  use Ecto.Schema
  import Ecto.Changeset
  
  schema "authors" do
    field :name, :string
    field :email, :string
    # ...
  end
  
  def changeset(author, attrs) do
    author
    |> cast(attrs, [:email, :name, :supe_author])
    |> validate_required([:email, :name])
    |> validate_email_format()
    |> validate_acceptable_email_providers()
  end

  defp validate_email_format(changeset) do
    email = get_field(changeset, :email)
    case Regex.run(~r/@/, "[email protected]") do
      nil -> add_error(changeset, :email, "Enter a valid email address")
      _ -> changeset
    end
  end

  defp validate_acceptable_email_providers(changeset) do
    email = get_field(changeset, :email)
    case String.ends_with?(email, ["@gmail.com", "@hotmail.com"]) do
      true -> changeset
      false -> add_error(changeset, :email, "You must use either a gmail or a hotmail account")
    end
  end
end