Cleaner request parameters in Elixir web applications 🙌
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Cleaner request parameters in Elixir web applications 🙌

BetterParams is a simple Elixir Plug that allows passed request parameters to be called as atoms instead of Strings. The sole purpose of this Plug is to pattern match on maps with atom keys instead of string keys in routers/controllers to calm my OCD down.


Once installed, it lets you pattern match request parameters like %{id: id} instead of %{"id" => id} in Phoenix applications:

# web/controllers/some_controller.ex

def show(conn, %{id: id}) do
  # do something

def create(conn, %{id: id, post: %{title: title, body: body}}) do
  # do something


  • Implementation uses String.to_existing_atom to prevent against DoS attacks, so it only converts those params to atoms that you use in your application.
  • You can continue to use String keys without breaking your existing matches if you want. All request parameters are available for both String and Atom keys (that have already been defined in the application).
  • This doesn't pollute your Request Logs with duplicate params.
  • For other Plug.Router based applications, you can also access request params similarly by calling them like conn.params[:id] or


Add better_params to your project dependencies in mix.exs:

def deps do
  [{:better_params, "~> 0.5.0"}]

Phoenix Framework

For Phoenix applications, call the plug at the end of the controller method in web/web.ex (inside the quote block):

# web/web.ex

def controller do
  quote do
    use Phoenix.Controller

    # Other stuff...

    plug BetterParams

Alternatively, you can also call it your Router Pipelines or in individual controllers directly.

Other Plug.Router Apps

For other applications using Plug.Router, call the Plug anytime after calling the :match and :dispatch plugs:

defmodule MyApp.Router do
  use Plug.Router

  plug :match
  plug :dispatch
  plug BetterParams

  # Rest of the router...

Removing String Keys Entirely

If your use case calls for a params object with only Atom keys, you may pass the option drop_string_keys to the plug. Much as it says on the can, this will replace the String-type keys altogether, rather than preserving them alongside the Atom keys.

plug BetterParams, drop_string_keys: true


  • Write Tests
  • Write Documentation
  • Symbolize the collective params map
  • Option to remove string keys entirely
  • Symbolize individual parameter maps (if the need arises)
    • path_params
    • body_params
    • query_params


  • Fork, Enhance, Send PR
  • Lock issues with any bugs or feature requests
  • Implement something from Roadmap
  • Spread the word ❤️


This package is available as open source under the terms of the MIT License.