Use template into others with different view and router

What You need is shared views…

If you want it on every view, you can also add it to your app layout, e.g. add the following to templates\layouts\app.html.eex:

 <%= render MyAppWeb.Shared.AuthView, "auth.html", conn: @conn %>

Thanks so much

As a sidenote I do it a little bit differently than in the link.

Often I add a helpers folder in lib/any_web/helpers. I add a bootstrap_helper, with corresponding view, and template folder. I add it globally in any_web.ex, like this…

  def view do
    quote do
      use Phoenix.View,
        root: "lib/any_web/templates",
        namespace: AnyWeb

      # Import convenience functions from controllers
      import Phoenix.Controller, only: [get_flash: 1, get_flash: 2, view_module: 1]

      # Use all HTML functionality (forms, tags, etc)
      use Phoenix.HTML

      # Here I import some custom helpers
      import AnyWeb.Helpers.CheckboxHelper
      import AnyWeb.Helpers.BootstrapHelper
      import AnyWeb.Helpers.WaffleHelper
      import AnyWeb.Helpers.BaseHelper

      import AnyWeb.ErrorHelpers
      import AnyWeb.Gettext
      alias AnyWeb.Router.Helpers, as: Routes
    end
  end

These are 2 simple functions I put in helper. One is using content_tag, one render a template.

defmodule AnyWeb.Helpers.BootstrapHelper do
  @moduledoc """
  This is the documentation for the Bootstrap 4 helpers.
  It includes also fa helper, for Font awesome
  """
  use Phoenix.HTML

...

  def flash(message, mode) do
    class = "alert alert-#{mode} alert-dismissible fade show"
    content_tag(:div, class: class, role: "alert") do
      [
        message,
        content_tag(:button, type: :button, class: :close, "data-dismiss": :alert, "aria-label": "Close") do
          content_tag(:span) do
            raw("×")
          end
        end
      ]
    end
  end

  @doc """
  Dropdown helper
  """
  def dropdown(options \\ []) do
    render("dropdown.html", options)
  end

Then, in any template, I have access to helper functions to simplify building components. Like this…

<%= flash("hello world", "alert") %>

The main difference with the linked example is I import helpers…

If one day I decide to change css framework, I would just replace bootstrap helper with a new one.