Todo List

Mix.install([
  {:jason, "~> 1.4"},
  {:kino, "~> 0.9", override: true},
  {:youtube, github: "brooklinjazz/youtube"},
  {:hidden_cell, github: "brooklinjazz/hidden_cell"}
])

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Create A New Mix Project

Create a new project in the projects folder called candy_store using the command line.

mix new todo_list --sup

Install Ecto Dependencies

Add the following to your dependencies in mix.exs.

{:ecto_sql, "~> 3.0"},
{:postgrex, ">= 0.0.0"}

Install dependencies with mix deps.get.

Generate The Repo

Set up the Ecto configuration by running the following from the project folder.

mix ecto.gen.repo -r TodoList.Repo

You may need to change your config/config.exs file to match the username and password of your local PostgreSQL installation.

For debugging instructions, see the Ecto Documentation.

config :todo_list, TodoList.Repo,
  database: "friends",
  username: "user",
  password: "pass",
  hostname: "localhost"

Add the following to your config/config.exs file.

config :todo_list,
  ecto_repos: [TodoList.Repo]

Add the Repo to the applications supervision tree in application.ex.

{TodoList.Repo, []}

Set Up The Database

In the project folder, run the following from the command line. This will create the corresponding database for your application.

mix ecto.create

Hopefully, everything should run, and you will see:

The database for TodoList.Repo has been created.

However, you may encounter a bug. Here are some debugging tips to consider.

• Ensure that the PostgreSQL service is running.
• Ensure that your PostgreSQL username and password match.

If you are stuck, you can speak with your instructor or classmates. You can also raise an issue on the DockYard Academy github with an explanation of your error.

Todo List

Now that we have a mix project with Ecto, you will create a to-do list application. We should be able to:

• create a to-do item
• get all to-do items
• update a to-do item
• delete a to-do item

Create An Item Migration

We can generate a new migration for items with:

mix ecto.gen.migration create_items

Define an :items table. Each item should have a :title, which is a :string.

Define An Item Schema

Define a TodoList.Item Schema. Each TodoList.Item should have a :title which is a :string.

Create An Item

Define a TodoList.create_item/1 function which should accept a map to create a TodoList.Item. The created TodoList.Item should persist in the database.

TodoList.create_item(%{title: "My Title"})
{:ok, %TodoList.Item{__meta__: #Ecto.Schema.Metadata<:loaded>, title: "My Title", id: 1})

Get Items

Define a TodoList.all_items/0 function which should retrieve all created TodoList.Items from the database.

TodoList.all_items()
{:ok, [%TodoList.Item{__meta__: #Ecto.Schema.Metadata<:loaded>, title: "My Title", id: 1}])

Update Item

Define a TodoList.update_item/2 function. It should update an existing TodoList.Item. It should accept the id of an item and a map of fields to update.

This new item should persist with the changes in the database.

TodoList.update_item(1, %{title: "My New Title"})
{:ok, [%TodoList.Item{__meta__: #Ecto.Schema.Metadata<:loaded>, title: "My New Title", id: 1}])

Delete Item

Define a TodoList.delete_item/1 function. It should delete an existing TodoList.Item from the database.

TodoList.update_item(1, %{title: "My New Title"})
{:ok, [%TodoList.Item{__meta__: #Ecto.Schema.Metadata<:loaded>, title: "My New Title", id: 1}])

(Bonus) Filter Items

Define a TodoList.all_items/1 function which accepts a map of params to search for. It should be able to search by the :title. It should also search by partially matching titles.

So "My" would find "My Title"

Hint You could filter using the Enum module, however, it will be more performant to rely on Ecto.Query..

TodoList.all_items(%{"My"})
{:ok, [%TodoList.Item{__meta__: #Ecto.Schema.Metadata<:loaded>, title: "My Title", id: 1}])

Mark As Completed

file_name = Path.basename(Regex.replace(~r/#.+/, __ENV__.file, ""), ".livemd")

progress_path = __DIR__ <> "/../progress.json"
existing_progress = File.read!(progress_path) |> Jason.decode!()

default = Map.get(existing_progress, file_name, false)

form =
  Kino.Control.form(
    [
      completed: input = Kino.Input.checkbox("Mark As Completed", default: default)
    ],
    report_changes: true
  )

Task.async(fn ->
  for %{data: %{completed: completed}} <- Kino.Control.stream(form) do
    File.write!(progress_path, Jason.encode!(Map.put(existing_progress, file_name, completed)))
  end
end)

form

Commit Your Progress

Run the following in your command line from the curriculum folder to track and save your progress in a Git commit. Ensure that you do not already have undesired or unrelated changes by running git status or by checking the source control tab in Visual Studio Code.

$ git checkout solutions
$ git checkout -b todo-list-exercise
$ git add .
$ git commit -m "finish todo list exercise"
$ git push origin todo-list-exercise

Create a pull request from your todo-list-exercise branch to your solutions branch. Please do not create a pull request to the DockYard Academy repository as this will spam our PR tracker.

DockYard Academy Students Only:

Notify your instructor by including @BrooklinJazz in your PR description to get feedback. You (or your instructor) may merge your PR into your solutions branch after review.

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