Rails DeCal Spring 2018 Homework 2

Introduction

Hey there! Welcome to homework 2 of the Rails DeCal. By this week, the course will have covered routes, simple ruby syntax, and basic CRUD statements.

As you complete this homework, refresh your browser to observe changes you expect. If that doesn't work, try restarting the server.

Per usual, Google and Stack Overflow are your best friends when debugging.

Setup:

To start everything off, fork this repository - there should be a fork button on the top right corner of the repo.

After you fork, run these commands to clone your newly forked repository:

git clone https://github.com/your_username/sp18-hw2
cd sp18-hw2

Next, install all the gems (Rails libraries) necessary by running:

bundle install

Then, start your server by running:

rails server

Try going to localhost:3000 in your browser. But wait...it's broken. What's going on? Routes? Undefined?

BUT WAIT (Preface)!

If you take a look at a couple of the classes in the app/controllers/concerns/ directory, you'll see some weird functions - attr_accessor and initialize.

initialize is similar to Python's __init__ method and is called every time you create a new object. If you do not define an initialize method, Ruby will just assume that your class has an empty initializor.

attr_accessor is used to define instance variables so that you can have both read access (via your_class.instance_variable) and edit access (via your_class.instance_variable = some_value). By default, instance variables are NOT accessible (getting or setting) outside of the class so you have to declare attr_accessor in order to enable this functionality. You can also be more specific and make some attributes readable (attr_readable) and some settable (attr_writer).

Also, you'll see a lot of <%= some_variable %>. This is embedded ruby, which we'll be covering next week.

A Note on Views

In lecture we saw how the router helped our web application translate HTTP requests into controller actions. If you remember the MVC diagram, the controller's final step is to return a view back to the client, so we can see the results. You will need to have a basic understanding of how this works in order to complete the homework problems.

For example, we have the following line of code in routes.rb:

get 'users', to: 'users#index'

When this HTTP request is received, it will be handled by the UsersController's index action:

class UsersController < ApplicationController
  def index
    @users = User.all
    render :index
  end
end

Take special note of the line render :index, and recall that Rails strives to be as minimally redundant as possible. This line looks through your users view folder (app/views/users) for a file called index.html.erb and then renders that. The naming is essential. How does it know to look through only the users view folder? Because this controller is named UsersController. If you misspell it or even use the singular form UserController you may face some nasty little bugs.

If that wasn't enough, the line render :index can actually be completely omitted:

def index
  @users = User.all
end

Since our method is named index, the default behavior is to automatically render the view called index.html.erb. Remember this well because you will very rarely see the explicit render statement again.

Alright, lets get crackin':

Question 1

Here, we're going to look into a POST request.

If you look closely at the code at home.html.erb, you'll see a bunch of confusing code like this:

<%= form_tag stringify_path do... %>

Don't worry if this is confusing to you. We'll be covering forms in the future. What is important is that a form POSTs a request to a endpoint/path.

To fix the errors, route a path in the routes.rb file so that a POST request to localhost:3000 (also known '/' or root) routes to the stringify method in pages_controller.rb. Be sure to give set the path prefix to stringify so we can reference it with the name stringify_path

Now that we've gone through that hassle, we now face our second problem. If you try to submit the form, you get a views error message (missing template pages/stringify) if you check terminal window where you are running your rails server!

To fix this, update app/controllers/concerns/stringify such that the what_am_i method returns "You are nothing!" if @name or @adjective are blank, but returns "your_name is so your_adjective" if @name and @adjective are not blank.

Hint: The method blank? may be helpful. Also refer to the first lecture if you need a refresher on boolean logic or how to structure if-else blocks.

Once you're done, create a stringify.html.erb view (where should this file go?) and add

<%= @text %>

to the view. Now when you submit the form, nothing should error and you should see the result of your what_am_i method.

Hint: The associated view file of a controller method (ex: 'pages#home') should be named 'home.html.erb' and placed in the views/pages directory.

Question 2

Now we're going to look at more routing + creating classes!

If you look at the Question 2 section on the home page, you'll see that we have another form! However, if you submit it you'll get an error message telling you that no route matches the request.

Let's fix this bug.

Step 1: <%= form_tag age_path, method: :put do %> tells Rails to create a PUT request to /age on form submission. Create an appropriate route in routes.rb to handle the form submission; direct it to the person method in pages_controller.rb, rather than the age method. This means that a GET request to /age will be handled by a different action than a PUT request to /age!

Step 2: in /controllers/concerns, implement a Person class whose initialize method accepts a name and age and creates an instance variable @nickname that is the first four letters of @name (use string/array splicing).

The Person class should have the following methods:

• introduce: returns a string with the instance's name and age
• birth_year: calculates what year they were born given an age in years (Bonus: try to implement this using Time.now.year)
  • Hint: the string to_i method might come in handy here
• nickname: returns the nickname

Submit the Question 2 form (which will direct you to localhost:3000/age) and validate you did this correctly.

Note: don't worry about blank form edge cases (which we practiced handling in Q1) and formatting.

Question 3

Let's practice some HTML/CSS:

Create a view that can be seen if you go to localhost:3000/me. Just a friendly reminder, to do this you'll have to create a route, a controller action, and a view.

In this view, render your name, where you're from, your year (freshman/sophomore/junior/senior/etc), a fun fact, and what you're most excited about in this class. Try to have fun with this part! :)

Bonus: add and render a picture of yourself (upload your file into assets/images). Check out the rails image_tag helper.

Bonus 2: use CSS to style your text (add background colors, underline it, anything you want!)

Go to localhost:3000/me and validate you did this correctly.

How to submit

You're done! Whew. Time to submit! Run these commands:

git add .
git commit -am "whatever message you want"
git push origin master

Fill out the submission form for this homework, which can be found on Piazza.