Blog: Blog Content

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: Blog Content

In your Blog project, you’re going to separate each blog posts content field into a separate PostContent resource. PostContent will have a one-to-one relationship with your blog Post resource.

Each PostContent record should store a full_text field and a foreign key to a post record.

classDiagram
  class PostContent {
    full_text: :text
    post_id: :id
  }

Requirements

Ensure you:

• Create a post_content table in a migration.
• Create a PostContent schema.
• Can create a Post with associated PostContent through your existing post form.
• Can update a Post with associated PostContent through your existing post form.
• Display the post content on the blog post show page.

You do not need to remove the existing :content field on the blog post. See the bonus exercise below.

Hint

Post Schema and Migration

You can use the following command to generate the PostContent schema and migration boilerplate.

$ mix phx.gen.schema Blog.PostContent post_content full_text:text post_id:references:posts

Post Form

You can use inputs_for/3 to create the associated post_content field.

PostContent Association

You can associate PostContent with Post using has_one/3 and belongs_to/3.

Creating Associated Post Content

You can use cast_assoc/3 inside of the Post schema’s changeset/2 function to create the associated :post_content.

Updating Associated Post Content

Ensure you preload the :post_content using Repo.preload/3 whenever updating a post.

Bonus: Migrate the :content Field Into PostContent.

Create a migration that will create an associated PostContent record for every existing Post record using their :content field. Then in the same migration, remove the :content field from every post.

This simulates a real-world production system where you would likely need to preserve existing data.

Make sure you also update any places in your codebase using the :content field to avoid errors. For example you likely need to fix your seed files, tests, templates, etc.

Mark As Completed

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

save_name =
  case Path.basename(__DIR__) do
    "reading" -> "blog_content_reading"
    "exercises" -> "blog_content_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-content-exercise
$ git add .
$ git commit -m "finish blog content exercise"
$ git push origin blog-content-exercise

Create a pull request from your blog-content-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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