Inject values on registration

[an0h]

hello i am just starting trying to implement pow and its slick, but i am unable to express in my elixir knowledge how to correctly use the before_process to inject a value into the conn and have it saved to the db, i get the conn updated to show the user object i desire but my injected values never save to the db.

the fields both work to save values if i input them in the form... just i have something i want to do autmoated wise reeal quick before i insert the record and i thought overwitint the conn is the way to do it, i tried a few ways to do this, is it possible or is there a more Elixir expressive way to update the record before inserting it?

This is my unsuccessful attempt, below:

  def before_process(Pow.Phoenix.RegistrationController, :create, conn, config) do
    IO.puts "beforeprocess"
    IO.inspect conn
    # ^ this conn here shows original form values
    %{params: %{"user" => user}} = conn
    with %{foo: foo, bar: bar} <- MyAppAssigner.find_user_unique(user) do
      conn = %{conn | body_params: %{conn.body_params | "user" => foo}}
      conn = %{conn | params: %{conn.params | "user" => foo}}
      IO.puts "i have modified conn"
      IO.inspect conn
      # ^ this conn shows desired user object in both params fields modified above, and then i return it?
      conn
    else
      e ->
        IO.inspect e
        conn
    end
  end

[danschultzer]

The controller callbacks (which uses before_process) are used in extensions, so you'll need to set this up as an extension.

There's a simpler approach using a plug:

defmodule MyAppWeb.Pow.InjectRegistrationPlug do
  @moduledoc """
  This plug injects attributes during user registration.

  ## Example

      plug MyAppWeb.Pow.InjectRegistrationPlug
  """

  def init(opts), do: opts

  def call(%{private: %{phoenix_controller: Pow.Phoenix.RegistrationController, phoenix_action: :new}} = conn, _opts) do
    case MyAppAssigner.find_user_unique(conn.params["user"]) do
      %{foo: foo, bar: bar} -> %{conn | params: %{conn.params | "user" => foo}}
      _else -> conn
    end
  end
end

Then you add this plug to the router.

Alternatively you could handle this in the context module:

defmodule MyApp.Users do
  use Pow.Ecto.Context,
    repo: MyApp.Repo,
    user: MyApp.Users.User

  def create(params) do
    params
    |> unique_user_params()
    |> pow_create(params)
  end

  defp unique_user_params(params) do
    case MyAppAssigner.find_user_unique(params) do
      %{foo: foo, bar: bar} -> foo
      nil -> params
    end
  end
end

In this case you need to update the config with users_context: MyApp.Users for it to pick up the custom context.

[an0h]

Thanks so very much for the elegant Elixir here on this issue, and most especially in this module!