Candy Store

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

Using the command line, create a new project in the projects folder called candy_store.

mix new candy_store

Candy Store

In this exercise, you will build a candy store application which searches and filters candy products from existing products. Each product should be a struct with a :name, :cost, and :type.

The :name will be a string. The :cost will be an integer (in cents). The :type will be an atom.

classDiagram
  Product {
    name: :string,
    cost: :integer,
    type: :atom
  }

Create An Item Struct

Create a CandyStore.Item module in a lib/item.ex file. It should be a struct with the :name, :cost, and :type fields.

:name, :cost, and :type should be enforced.

Create the following test cases for CandyStore.Item.

Test The Item Struct

Create a CandyStore.ItemTest module in tests/item_test.ex.

Create the following test cases for the following:

• given a :name, :cost, and :type field it should create an Item struct.
• The Item struct should enforce the :name and :type fields.

Create The CandyStore.search/2 Function

The CandyStore.search/2 function should take a list of items, and the a search query to filter them by. For example,

items = [%Item{name: "AAA", type: :candy_bar, cost: 120}, %Item{name: "BBB", type: :candy_bar, cost: 120}, ]
query = %{name: "A", type: :candy_bar, cost: 120}
CandyStore.search(items, query)
%Item{name: "AAA", type: :candy_bar, cost: 120}

Create a CandyStore.search/2 function and the following test cases: (You may use any test names, so long as your tests cover the following functionality)

• given a list of items, when searching the full name of one item, then it should only find matching items.
• given a list of items, when searching the partial name of one item, then it should only find matching items.
• given a list of items, when searching the a non matching name, it should find no items.
• given a list of items, when searching by type, it should find matching items.
• given a list of items, when searching by a non-matching type, it should find no items.
• given a list of items, when searching by exact cost, it should find matching items.
• given a list of items, when searching by all filters (:type, :cost, and :name) it should find matching items.

Ensure all tests pass.

(Bonus) Search By Price

Add the following functionality and cases to allow users to search by price:

• given a list of items, when searching by :max_cost, it should find items below the max cost.
• given a list of items, when searching by :min_cost, it should find items below the max cost.
• given a list of items, when searching by :cost with a range, it should find items within the range.

(Bonus) Item Validation

Use Ecto Changesets validate the Item struct in an Item.new/1 function. :name must be a string. :type must be an atom. :cost must be an integer.

Then create the following test cases:

• Item.new/1 should return a changeset error if :name is not a string.
• Item.new/1 should return a changeset error if :type is not an atom.
• Item.new/1 should return a changeset error if :cost is not a integer.
• Item.new/1 should return a struct if :name, :type, and :cost are all valid.

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 candy-store-exercise
$ git add .
$ git commit -m "finish candy store exercise"
$ git push origin candy-store-exercise

Create a pull request from your candy-store-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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