MVC in Action

MVC in Action!

Setup

For this class, we’ll be playing in this repo.

For each of the code snippets below, take a few minutes to identify where we are breaking MVC logic conventions. Then, we will talk as a class about how we should fix each infraction.

Imagine that you are working on an app that tracks comedians and their Netflix specials. Comedians have an age, and they also have Specials in a one to many relationship. Specials have a runtime (length of the show in minutes).

Models

class Comedian < ApplicationRecord
  has_many :specials

  def self.average_age
    "#{average(:age).round(2)} Years"
  end

  def average_special_runtime
    specials.average(:runtime)
  end
end

Views

app/views/comedians/index.html.erb

<% @comedians.each do |comic| %>
<h4><%= comic.specials.count %> Specials</h4>
<% end %>

app/views/comedians/show.html.erb

<h1><%= @comedian.name %></h1>
<% if @comedian.specials.count > 2 && @longest_special > 20 %>
  <p>Average runtime of all this comedian's specials: <%= @average_special_runtime %></p>
<% end %>

Controllers

class ComediansController < ApplicationController
  def index
    @comedians = Comedian.all
    @average_age = Comedian.average(:age)
  end
end

class ComediansController < ApplicationController
  def show
    @comedian = Comedian.find(params[:id])
    @average_special_runtime = @comedian.average_special_runtime.round(2)
    @longest_special = @comedian.specials.order(runtime: :desc).first
  end
end

Peer Code Review

In small groups, review each other’s projects. Help each other identify places where there are MVC infractions similar to the infractions in the code snippets above.

• Set a timer to ensure each group has equal time to share.
• DO NOT spend time attempting to refactor your code when you identify problem areas.
• Instead, write yourself a comment in your code like #MVC, so that you and your partner can come back to it on your own time.

For additional guidance, consider the following rules:

• No query logic in your Controllers or Views; this should live in your Models.
• No data formatting in your Models or Controllers; this should live in your Views.

Further Learning

A completed version of this lesson can be found here.