Protocol for normalizing a paginated result into scroll metadata (and, optionally, the page's entries) for use with Inertia.Controller.inertia_scroll/2.

Implementations return a map. Pagination structs that carry their own entries (such as Scrivener.Page) include an :entries key; metadata-only structs (such as Flop.Meta, where the records are returned separately) omit it, and the entries are taken from the {entries, meta} tuple passed to inertia_scroll.

Return value

A map with any of the following keys (omitted keys fall back to defaults):

• :entries - The list of items on the page (include this only for self-contained pagination structs)
• :page_name - The query parameter name for pagination (defaults to "page")
• :current_page - The current page
• :previous_page - The previous page, or nil if on the first page
• :next_page - The next page, or nil if on the last page

Example: a struct that carries its entries

defimpl Inertia.Paginated, for: Scrivener.Page do
  def to_scroll(%{entries: entries, page_number: page, total_pages: total}) do
    %{
      entries: entries,
      current_page: page,
      previous_page: if(page > 1, do: page - 1),
      next_page: if(page < total, do: page + 1)
    }
  end
end

Example: a metadata-only struct

defimpl Inertia.Paginated, for: MyPaginator.Meta do
  def to_scroll(meta) do
    %{
      current_page: meta.current_page,
      previous_page: meta.previous_page,
      next_page: meta.next_page
    }
  end
end

# used as:
assign_prop(conn, :users, inertia_scroll({records, meta}))