ConstructParams

Casting the incoming controller parameters

Installation

If available in Hex, the package can be installed by adding construct_params to your list of dependencies in mix.exs:

def deps do
  [
    {:construct_params, "~> 0.3.0"}
  ]
end

Documentation can be found at https://hexdocs.pm/construct_params.

Usage

ConstractParams provides a macro for controller params casting.

1. First, you need to create a module that cast the input parameters.
   For casting uses construct library.

defmodule MyAppWeb.Api.Requests.Users.Index do
  use Construct do
    field(:next_page, :string, default: nil)
    field(:limit, :integer, default: nil)
    field(:user_id, :integer, default: nil)
  end
end

2. Then add a decorator to the action with the parameters you want to cast.

defmodule MyAppWeb.Api.UsersController do
  use ConstructParams.CastDecorator

  @decorate cast(MyAppWeb.Api.Requests.Users.Index)
  def index(conn, params) do
  end
end

In case of a successful casting, the controller action params are replaced with the casted data.
Otherwise the appropriate FallbackController is called with {:error, errors} parameters.