Implement .render_subject/2 and .render_subject/3

[swoosh]

Implement .render_subject/2 and .render_subject/3

[stevedomin]

Hello @sitch.

Thanks for opening an issue!

Would you mind sharing more details about your use-case? I'm struggling to see where this would be more powerful than a simple string interpolation?

Thanks!

[sitch]

Well firstly, rendering the subject as a template can be useful non-devs to maintain the templates. My use case is more that i am passing an assigns map to render_body/3 or to Swoosh.Email.new/1, and I can just repeat myself or i can access those assigns variables for consistency

[sitch]

This is what i'm using internally to do:

new()
|> assign(:name, "Sitch")
|> render_subject(~S("Welcome #{name}"))
|> render_body("template.html")

defmodule RenderingSubject do

  def render_subject(%Swoosh.Email{assigns: assigns} = struct, template) do
    subject = eval_quoted_string(template, assigns)
    %{struct | subject: subject}
  end

  def eval_quoted_string(template, assigns) when is_binary(template) and is_map(assigns) do
    with assignment_list <- Enum.into(assigns, []),
         {result, _assign} <- Code.eval_string(template, assignment_list)
    do
      result
    else
      _ -> raise "Unknown argument in .eval_quoted_string/2"
    end
  end
end