Functional Programming: A PragPub Anthology

Creating Custom Entities

You can create something other than maps or structs. To do so, you just need to tell Blacksmith how. Elixir has a JSON library called Poison. Let’s create a Forge that tells Blacksmith how to create a new JSON hash from an Elixir map, like this:

~~~
defmodule JsonForge do
  use Blacksmith

  @new_function &Blacksmith.Config.new_json/2

  register :user,
    name: "John Henry",
    email: Faker.Internet.email
end

defmodule Blacksmith.Config do
  def new_json(attributes, overrides) do
    attributes
    |> Dict.merge( overrides )
    |> Poison.Encoder.encode([])
  end
end
~~~

You can see a Forge with two specific enhancements. The first is the attribute variable, @new_function. Blacksmith creates maps, and that function ...