Implement basic API

Author: ChristianAlexander

lib/todo_backend/todos.ex

@@ -0,0 +1,117 @@
+defmodule TodoBackend.Todos do
+  @moduledoc """
+  The Todos context.
+  """
+
+  import Ecto.Query, warn: false
+  alias TodoBackend.Repo
+
+  alias TodoBackend.Todos.Todo
+
+  @doc """
+  Returns the list of todos.
+
+  ## Examples
+
+      iex> list_todos()
+      [%Todo{}, ...]
+
+  """
+  def list_todos do
+    Repo.all(Todo)
+  end
+
+  @doc """
+  Gets a single todo.
+
+  Raises `Ecto.NoResultsError` if the Todo does not exist.
+
+  ## Examples
+
+      iex> get_todo!(123)
+      %Todo{}
+
+      iex> get_todo!(456)
+      ** (Ecto.NoResultsError)
+
+  """
+  def get_todo!(id), do: Repo.get!(Todo, id)
+
+  @doc """
+  Creates a todo.
+
+  ## Examples
+
+      iex> create_todo(%{field: value})
+      {:ok, %Todo{}}
+
+      iex> create_todo(%{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def create_todo(attrs \\ %{}) do
+    %Todo{}
+    |> Todo.changeset(attrs)
+    |> Repo.insert()
+  end
+
+  @doc """
+  Updates a todo.
+
+  ## Examples
+
+      iex> update_todo(todo, %{field: new_value})
+      {:ok, %Todo{}}
+
+      iex> update_todo(todo, %{field: bad_value})
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def update_todo(%Todo{} = todo, attrs) do
+    todo
+    |> Todo.changeset(attrs)
+    |> Repo.update()
+  end
+
+  @doc """
+  Deletes a todo.
+
+  ## Examples
+
+      iex> delete_todo(todo)
+      {:ok, %Todo{}}
+
+      iex> delete_todo(todo)
+      {:error, %Ecto.Changeset{}}
+
+  """
+  def delete_todo(%Todo{} = todo) do
+    Repo.delete(todo)
+  end
+
+  @doc """
+  Deletes all todos.
+
+  ## Examples
+
+      iex> delete_all_todos()
+      {deleted_count, nil}
+
+  """
+  def delete_all_todos() do
+    Repo.delete_all(Todo)
+  end
+
+  @doc """
+  Returns an `%Ecto.Changeset{}` for tracking todo changes.
+
+  ## Examples
+
+      iex> change_todo(todo)
+      %Ecto.Changeset{data: %Todo{}}
+
+  """
+  def change_todo(%Todo{} = todo, attrs \\ %{}) do
+    Todo.changeset(todo, attrs)
+  end
+end

lib/todo_backend/todos/todo.ex

@@ -0,0 +1,18 @@
+defmodule TodoBackend.Todos.Todo do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  schema "todos" do
+    field :completed, :boolean, default: false
+    field :title, :string
+
+    timestamps()
+  end
+
+  @doc false
+  def changeset(todo, attrs) do
+    todo
+    |> cast(attrs, [:title, :completed])
+    |> validate_required([:title, :completed])
+  end
+end

lib/todo_backend_web/controllers/fallback_controller.ex

@@ -0,0 +1,24 @@
+defmodule TodoBackendWeb.FallbackController do
+  @moduledoc """
+  Translates controller action results into valid `Plug.Conn` responses.
+
+  See `Phoenix.Controller.action_fallback/1` for more details.
+  """
+  use TodoBackendWeb, :controller
+
+  # This clause handles errors returned by Ecto's insert/update/delete.
+  def call(conn, {:error, %Ecto.Changeset{} = changeset}) do
+    conn
+    |> put_status(:unprocessable_entity)
+    |> put_view(TodoBackendWeb.ChangesetView)
+    |> render("error.json", changeset: changeset)
+  end
+
+  # This clause is an example of how to handle resources that cannot be found.
+  def call(conn, {:error, :not_found}) do
+    conn
+    |> put_status(:not_found)
+    |> put_view(TodoBackendWeb.ErrorView)
+    |> render(:"404")
+  end
+end

lib/todo_backend_web/controllers/todo_controller.ex

@@ -0,0 +1,51 @@
+defmodule TodoBackendWeb.TodoController do
+  use TodoBackendWeb, :controller
+
+  alias TodoBackend.Todos
+  alias TodoBackend.Todos.Todo
+
+  action_fallback TodoBackendWeb.FallbackController
+
+  def index(conn, _params) do
+    todos = Todos.list_todos()
+    render(conn, "index.json", todos: todos)
+  end
+
+  def create(conn, todo_params) do
+    with {:ok, %Todo{} = todo} <- Todos.create_todo(todo_params) do
+      conn
+      |> put_status(:created)
+      |> put_resp_header("location", Routes.todo_path(conn, :show, todo))
+      |> render("show.json", todo: todo)
+    end
+  end
+
+  def show(conn, %{"id" => id}) do
+    todo = Todos.get_todo!(id)
+    render(conn, "show.json", todo: todo)
+  end
+
+  def update(conn, %{"id" => id}) do
+    todo = Todos.get_todo!(id)
+
+    update_values = conn.body_params
+
+    with {:ok, %Todo{} = todo} <- Todos.update_todo(todo, update_values) do
+      render(conn, "show.json", todo: todo)
+    end
+  end
+
+  def delete(conn, %{"id" => id}) do
+    todo = Todos.get_todo!(id)
+
+    with {:ok, %Todo{}} <- Todos.delete_todo(todo) do
+      send_resp(conn, :no_content, "")
+    end
+  end
+
+  def delete_all(conn, _params) do
+    Todos.delete_all_todos()
+
+    send_resp(conn, :no_content, "")
+  end
+end

lib/todo_backend_web/router.ex

@@ -7,5 +7,8 @@ defmodule TodoBackendWeb.Router do
 
   scope "/api", TodoBackendWeb do
     pipe_through :api
+
+    resources "/todos", TodoController
+    delete "/todos", TodoController, :delete_all
   end
 end

lib/todo_backend_web/views/changeset_view.ex

@@ -0,0 +1,19 @@
+defmodule TodoBackendWeb.ChangesetView do
+  use TodoBackendWeb, :view
+
+  @doc """
+  Traverses and translates changeset errors.
+
+  See `Ecto.Changeset.traverse_errors/2` and
+  `TodoBackendWeb.ErrorHelpers.translate_error/1` for more details.
+  """
+  def translate_errors(changeset) do
+    Ecto.Changeset.traverse_errors(changeset, &translate_error/1)
+  end
+
+  def render("error.json", %{changeset: changeset}) do
+    # When encoded, the changeset returns its errors
+    # as a JSON object. So we just pass it forward.
+    %{errors: translate_errors(changeset)}
+  end
+end

lib/todo_backend_web/views/todo_view.ex

@@ -0,0 +1,22 @@
+defmodule TodoBackendWeb.TodoView do
+  use TodoBackendWeb, :view
+  alias TodoBackendWeb.TodoView
+  alias TodoBackendWeb.Endpoint
+
+  def render("index.json", %{todos: todos}) do
+    render_many(todos, TodoView, "todo.json")
+  end
+
+  def render("show.json", %{todo: todo}) do
+    render_one(todo, TodoView, "todo.json")
+  end
+
+  def render("todo.json", %{todo: todo}) do
+    %{
+      id: todo.id,
+      title: todo.title,
+      completed: todo.completed,
+      url: Routes.todo_url(Endpoint, :show, todo.id)
+    }
+  end
+end

priv/repo/migrations/20220508015106_create_todos.exs

@@ -0,0 +1,12 @@
+defmodule TodoBackend.Repo.Migrations.CreateTodos do
+  use Ecto.Migration
+
+  def change do
+    create table(:todos) do
+      add :title, :string
+      add :completed, :boolean, default: false, null: false
+
+      timestamps()
+    end
+  end
+end

test/support/fixtures/todos_fixtures.ex

@@ -0,0 +1,21 @@
+defmodule TodoBackend.TodosFixtures do
+  @moduledoc """
+  This module defines test helpers for creating
+  entities via the `TodoBackend.Todos` context.
+  """
+
+  @doc """
+  Generate a todo.
+  """
+  def todo_fixture(attrs \\ %{}) do
+    {:ok, todo} =
+      attrs
+      |> Enum.into(%{
+        completed: true,
+        title: "some title"
+      })
+      |> TodoBackend.Todos.create_todo()
+
+    todo
+  end
+end

test/todo_backend/todos_test.exs

@@ -0,0 +1,61 @@
+defmodule TodoBackend.TodosTest do
+  use TodoBackend.DataCase
+
+  alias TodoBackend.Todos
+
+  describe "todos" do
+    alias TodoBackend.Todos.Todo
+
+    import TodoBackend.TodosFixtures
+
+    @invalid_attrs %{completed: nil, title: nil}
+
+    test "list_todos/0 returns all todos" do
+      todo = todo_fixture()
+      assert Todos.list_todos() == [todo]
+    end
+
+    test "get_todo!/1 returns the todo with given id" do
+      todo = todo_fixture()
+      assert Todos.get_todo!(todo.id) == todo
+    end
+
+    test "create_todo/1 with valid data creates a todo" do
+      valid_attrs = %{completed: true, title: "some title"}
+
+      assert {:ok, %Todo{} = todo} = Todos.create_todo(valid_attrs)
+      assert todo.completed == true
+      assert todo.title == "some title"
+    end
+
+    test "create_todo/1 with invalid data returns error changeset" do
+      assert {:error, %Ecto.Changeset{}} = Todos.create_todo(@invalid_attrs)
+    end
+
+    test "update_todo/2 with valid data updates the todo" do
+      todo = todo_fixture()
+      update_attrs = %{completed: false, title: "some updated title"}
+
+      assert {:ok, %Todo{} = todo} = Todos.update_todo(todo, update_attrs)
+      assert todo.completed == false
+      assert todo.title == "some updated title"
+    end
+
+    test "update_todo/2 with invalid data returns error changeset" do
+      todo = todo_fixture()
+      assert {:error, %Ecto.Changeset{}} = Todos.update_todo(todo, @invalid_attrs)
+      assert todo == Todos.get_todo!(todo.id)
+    end
+
+    test "delete_todo/1 deletes the todo" do
+      todo = todo_fixture()
+      assert {:ok, %Todo{}} = Todos.delete_todo(todo)
+      assert_raise Ecto.NoResultsError, fn -> Todos.get_todo!(todo.id) end
+    end
+
+    test "change_todo/1 returns a todo changeset" do
+      todo = todo_fixture()
+      assert %Ecto.Changeset{} = Todos.change_todo(todo)
+    end
+  end
+end