How to get struct from map - elixir?

Questions & Help Questions
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23

I tend to use Ecto and embedded schemas for map → struct and boundary validation like this:

defmodule MyApp.MyContext do
  def do_the_thing(params \\ %{}) when is_map(params) do
    with {:ok, command} <- MyApp.MyContext.Commands.DoTheThing.new(params) do
      # fun business logic here
    end
  end
end

defmodule MyApp.MyContext.Commands.DoTheThing do
  use Ecto.Schema
  import Ecto.Changeset

  embedded_schema do
    field :field_1, :string
    field :field_2, :integer
  end

  def new(params) do
    command = changeset(params)
    case command.valid? do
      true  -> {:ok, apply_changes(command)}
      false -> {:error, command.errors}
    end
  end

  defp changeset(params) do
    %__MODULE__{}
    |> cast(params, [:field_1, :field_2])
    |> validate_required([:field_1, :field_2])
  end
end

It doesn’t feel so dirty to do this since Ecto 3.0 and the :ecto_sql separation.

I’ve found this to be a good way to accept large form inputs - maybe not as practical for smaller sets of parameters.