Blog: Migration

Mix.install([
  {:jason, "~> 1.4"},
  {:kino, "~> 0.8.0", override: true},
  {:youtube, github: "brooklinjazz/youtube"},
  {:hidden_cell, github: "brooklinjazz/hidden_cell"}
])

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Blog: Migration

Your existing Blog application should already have blog posts with a title, subtitle, and content.

Blog Post Migration

You’re going to create a migration or many migrations to modify the blog posts table with the following changes:

• Remove the subtitle field
• Add a published_on :date field.
• Add a visible :boolean field which defaults to true.

Ensure your Post schema reflects these changes, and ensure all tests pass. Modify existing tests to include the new fields.

Ensure all features of your application such as creating, reading, updating, and deleting posts continue to work. You will likely need to modify any pages using old fields that are no longer valid.

Form Fields

Add a date input for the published_on field, and a checkbox input for the visible field.

Use the IEx shell to view all Post records to ensure your form correctly creates a blog post.

iex -S mix

Visibility

When displaying a list of blog posts, hide any blog posts whose visible field is false or whose published_on field is after the current UTC date.

Push to GitHub

From the blog folder run the following commands.

First, ensure that all tests pass.

mix test

Then create a pull request, review it, and merge it into your main branch.

Bonus: Constraints

Create another migration to add the following constraints:

• Modify the title field to be unique.
• Modify the title so it must be between 3 and 100 characters.

Ensure your Post schema reflects these constraints and validations.

Mark As Completed

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

save_name =
  case Path.basename(__DIR__) do
    "reading" -> "blog_migration_reading"
    "exercises" -> "blog_migration_exercise"
  end

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

default = Map.get(existing_progress, save_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, save_name, completed), pretty: true)
    )
  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 -b blog-migration-exercise
$ git add .
$ git commit -m "finish blog migration exercise"
$ git push origin blog-migration-exercise

Create a pull request from your blog-migration-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 teacher by including @BrooklinJazz in your PR description to get feedback. You (or your teacher) may merge your PR into your solutions branch after review.

If you are interested in joining the next academy cohort, sign up here to receive more news when it is available.

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