normalize.ex

defmodule Normalize do
  import Ecto.Changeset

  @spec normalize(map(), Keyword.t()) :: {:ok, map()} | {:error, Ecto.Changeset.t()}
  def normalize(params, input_schema) do
    types =
      Map.new(input_schema, fn {field, opts} ->
        {field, List.first(opts)}
      end)

    changeset =
      for {field, opts} <- input_schema,
          opt <- opts,
          reduce: cast({%{}, types}, params, Map.keys(types)) do
        changeset ->
          case opt do
            {:required, true} -> validate_required(changeset, field)
            _opt -> changeset
          end
      end

    apply_action(changeset, :insert)
  end
end

input_schema = [
  title: [:string, required: true],
  slug: [:string]
]

params = %{"title" => "Hello", "slug" => "hello", "world" => "hello"}

Normalize.normalize(params, input_schema)