Phoenix Select Form Helper

The select form helper allows you to easily add a select input to your forms.

= form_for @changeset, resource_path(@conn, :create), fn f ->
  = select f, :book_id, @books
  = submit "Save Post", class: "btn"

Among the types of arguments that the select helper can accept are two-item tuples. The first item in the tuple is used as the label for the option and the second item is used as the value for the option.

Media.list_books returns a list of structs representing all of the books in the database. We'll need to get from a list of structs to a list of tuples.

To do that, we'll pipe the list of Book structs to Enum.map and use an anonymous function to generate two-value tuples from those structs.

def new(conn, _params)
  ...
  books =
    Media.list_books
      |> Enum.map(&{"#{&1.title} by #{&1.author}", &1.id})

  render conn, "new.html", changeset: changeset, books: books
end