Media Prototype

attachment.ex

defmodule Blog.Attachment do
  use Blog, :schema

  @primary_key {:id, :binary_id, autogenerate: true}
  @storage_path "attachments"

  schema "attachments" do
    field :file, :any, virtual: true
    belongs_to :post, Post

    timestamps()
  end

  def changeset(schema, params \\ %{}) do
    schema
    |> cast(params, [:id, :file])
    |> validate_required([])
    |> prepare_changes(&save_attachment/1)
  end

  def path(attachment, opts \\ []) do
    version   = Keyword.get(opts, :version, :original)
    extension = Keyword.get(opts, :extension, ".png")
    Path.join([@storage_path, attachment.id, "#{version}#{extension}"])
  end

  defp save_attachment(changeset) do
    uuid         = Ecto.UUID.generate()
    storage_path = Path.join([@storage_path, uuid])
    file         = changeset.changes.file

    Media.new(source: Media.File.new(file))
    |> Media.put_name(fn _, version -> version end)
    |> Media.put_extension("png")
    |> Media.put_storage_path(storage_path)
    |> Media.put_type("image/png")
    |> Media.transform(:original)
    |> Media.validate(fn media -> media.source.extension in ~w(.png .jpg .jpeg) end)
    |> Media.save()

    put_change(changeset, :id, uuid)
  end
end