Generating Example Data in Elixir

factory.ex

defmodule App.Factory do
  alias App.Repo

  def create(module, overrides \\ %{})
  
  def create(module, overrides) when is_list(overrides), do: create(module, Map.new(overrides))
  
  def create(module, overrides) do
    attributes = module.example() |> Map.merge(overrides)
    struct(module)
    |> changeset(attributes)
    |> Repo.insert!()
  end
  
  def changeset(%App.User{} = struct, attributes) do
    App.User.registration_changeset(struct, attributes)
  end
  
  def changeset(%{__struct__: module} = struct, attributes) do
    module.changeset(struct, attributes)
  end
end

schema.ex

defmodule App.User do
  use App.Web, :model
  alias App.Repo

  schema "users" do
    field(:name, :string)

    timestamps()

    belongs_to(:account, App.Account)
  end

  def changeset(struct, params \\ %{}) do
    struct
    |> cast(params, [:name])
    |> validate_required([:name])
  end
  
  def example do
    %{
      name: Faker.Person.name(),
      address: Faker.Address.street_address()
    }
  end
end

usage.ex

import App.Factory

account = create(App.Account, name: "My Company")
user = create(App.User, account_id: account.id) # %App.User{name: "Steve Urkel", account_id: 1}