defmodule Example.User do
@moduledoc """
User module with basic CRUD operations
"""
defstruct [:id, :name, :email, active: true]
@type t :: %__MODULE__{
id: integer(),
name: String.t(),
email: String.t(),
active: boolean()
}
@spec create_user(String.t(), String.t()) :: t()
def create_user(name, email) do
%__MODULE__{
id: generate_id(),
name: name,
email: email
}
end
@spec get_display_name(t()) :: String.t()
def get_display_name(%__MODULE__{name: name, active: true}), do: name
def get_display_name(%__MODULE__{name: name, active: false}), do: "#{name} (inactive)"
defp generate_id do
:os.system_time(:millisecond)
end
end
defmodule Example.UserRepository do
@moduledoc """
In-memory user repository using Agent
"""
use Agent
alias Example.User
def start_link(initial_users \\ []) do
Agent.start_link(fn -> initial_users end, name: __MODULE__)
end
@spec save(User.t()) :: User.t()
def save(%User{} = user) do
Agent.update(__MODULE__, fn users -> [user | users] end)
user
end
@spec find_by_id(integer()) :: User.t() | nil
def find_by_id(id) do
Agent.get(__MODULE__, fn users ->
Enum.find(users, &(&1.id == id))
end)
end
@spec find_by_email(String.t()) :: User.t() | nil
def find_by_email(email) do
Agent.get(__MODULE__, fn users ->
Enum.find(users, &(&1.email == email))
end)
end
@spec find_all() :: [User.t()]
def find_all do
Agent.get(__MODULE__, & &1)
end
@spec delete_by_id(integer()) :: boolean()
def delete_by_id(id) do
Agent.get_and_update(__MODULE__, fn users ->
{user_exists?, remaining_users} =
users
|> Enum.split_with(&(&1.id == id))
|> case do
{[], users} -> {false, users}
{_found, users} -> {true, users}
end
{user_exists?, remaining_users}
end)
end
end
