cn-class / saas1_hw2

CS169.1x - Homework 2: Introduction to Rails (RottenPotatoes)

Deploy RottenPotatoes and Enhancement #1

Part A —Add some movies to RottenPotatoes, and deploy it to the world

We have a version of RottenPotatoes that has had some slight modifications for successful deployment on Heroku, and to which we've added an additional handful of movies to make things more interesting. Check out the app on your VM (or other development environment) by running the following commands:

git clone git://github.com/saasbook/hw2_rottenpotatoes.git
cd hw2_rottenpotatoes

The first command will pull down the latest version of the RottenPotatoes starter code, and the second will move you into the directory which now contains the code.

The next step is to install the necessary gems for the app. Do this by running

bundle install --without production

The --without production part of the command causes the installer to ignore the PostgreSQL gem for your local installation (since that gem will cause problems if you're using a development environment without PostgreSQL installed).

Note that we provided a seed file that seeds the database with a bunch of movies. Take a look at the code in db/seeds.rb to review how these work. When you're ready, run

rake db:migrate

to apply all RottenPotatoes migrations to your local database. Then run

rake db:seed

to seed your local database with the movies from the seed file.

Verify that you can successfully run the app by using the command

rails server

If this works properly, you should be able to interact with RottenPotatoes via a web browser as described in the book and in lecture. Check that you can see a list of all the movies when you access 'localhost:3000/movies'.

Once the above steps have been verified on your development computer, it's time to deploy on Heroku. Create a free Heroku.com account if you haven't already, and deploy RottenPotatoes there. Appendix A in the textbook has more information about this procedure, and Heroku has detailed help pages as well. (Note that your app's name, something.herokuapp.com, must be unique among Heroku apps. It's therfore unlikely that the name "rottenpotatoes" will be available. You must either choose a different name or you may just keep the default name Heroku chooses for you when you create a new app.)

Since this is the first deployment of this app on Heroku, its database will be empty. To fix this, after you've pushed your app to Heroku, run

heroku run rake db:migrate

to apply all RottenPotatoes migrations. In this case, we only have one migration file that creates the Movies table (which had already been applied when you got your VM). You will also need to run

heroku run rake db:seed

to seed your Heroku app's database with the movies we've created in seeds.rb.

Visit your site at your-app-name.herokuapp.com/movies to verify that it’s working.

Part B — RottenPotatoes Enhancement #1: Sorting the list of all movies

You will enhance RottenPotatoes in the following ways:

• On the "All Movies" page, the column headings for "Movie Title" and "Release Date" for a movie should be clickable links. Clicking one of them should cause the list to be reloaded but sorted in ascending order on that column. Namely, 1. clicking the "Movie Title" column should list the movies alphabetically by title (for movies whose names begin with non-letters, the sort order should match the behavior of String#<=>), and 2. clicking the "Release Date" column heading should redisplay the list of movies with the earliest-released movies first.
• When the listing page is redisplayed with sorting-on-a-column enabled, the column header that was selected for sorting should appear with a yellow background, as shown below. You should do this by setting controller variables that are used to conditionally set the CSS class of the appropriate table heading to hilite, and pasting this simple CSS snippet into RottenPotatoes's app/assets/stylesheets/application.css file.

RottenPotatoes Enhancement #2: Filter the List of Movies

In this portion of the assignment, you will creating functionality within RottenPotatoes that allows the user to filter movies by MPAA rating. The filter will be controlled by checkboxes at the top of the "All Movies" listing.

When the "Refresh" button is pressed, the list of movies is redisplayed showing only those movies whose ratings were checked.

This will require a couple of pieces of code. We have provided the code that generates the checkboxes form, which you can include in the index.html.haml template, here on Pastebin. However, you have to do a bit of work to use it: our code expects the variable @all_ratings to be an enumerable collection of all possible values of a movie rating, such as ['G','PG','PG-13','R']. The controller method needs to set up this variable. And since the possible values of movie ratings are really the responsibility of the Movie model, it's best if the controller sets this variable by consulting the Model. Create a class method of Movie that returns an appropriate value for this collection.

You will also need code that figures out (i) how to figure out which boxes the user checked and (ii) how to restrict the database query based on that result.

Regarding (i), try viewing the source of the movie listings with the checkbox form, and you'll see that the checkboxes have field names like ratings[G], ratings[PG], etc. This trick will cause Rails to aggregate the values into a single hash called ratings, whose keys will be the names of the checked boxes only and whose values will be the value attribute of the checkbox which is "1" by default, since we didn't specify another value when calling the check_box_tag helper. That is, if the user checks the 'G' and 'R' boxes, params will include as one if its values :ratings=>{"G"=>"1", "R"=>"1"}. Check out the Hash documentation for an easy way to grab just the keys of a hash, since we don't care about the values in this case.

Regarding (ii), you'll probably end up replacing Movie.all`` with Movie.find```, which has various options to help you restrict the database query.

Specific Requirements

• Make sure that you don't break the sorted-column functionality you added in part 1B! That is, sorting by column headers should still work, and if the user then clicks the "Movie Title" column header to sort by movie title, the displayed results should both be sorted and be limited by the Ratings checkboxes.
• If the user checks (say) 'G' and 'PG' and then redisplays the list, the checkboxes that were used to filter the output should appear checked when the list is redisplayed. This will require you to modify the checkbox form slightly from the version we provided above.
• The first time the user visits the page, all checkboxes should be checked by default (so the user will see all movies). For now, ignore the case when the user unchecks all checkboxes—you will get to this in the next part.

RottenPotatoes Enhancement #3: Remember the Settings

Now that you have implemented parts 1 and 2, the user can click on the "Movie Title" or "Release Date" headings and see movies sorted by those columns, and can additionally use the checkboxes to restrict the listing to movies with certain ratings only. Moreover, we have preserved RESTfulness, because the URI itself always contains the parameters that will control sorting and filtering.

The last step is to remember these settings. That is, if

• the user has selected any combination of column sorting and restrict-by-rating constraints,
• and then the user clicks to see the details of one of the movies (for example),

then when she clicks "Back to movie list" on the detail page, the movie listing should "remember" the user's sorting and filtering settings from before.

(Clicking away from the list to see the details of a movie is only one example; the settings should be remembered regardless of what actions the user takes, so that any time she visits the index page, the settings are correctly reinstated.)

The best way to do the "remembering" will be to use the session[] hash. The session is like the flash[], except that once you set something in the session[] it is remembered "forever" until you nuke the session with session.clear or selectively delete things from it with session.delete(:some_key). That way, in the index method, you can selectively apply the settings from the session[] even if the incoming URI doesn't have the appropriate params[] set.

To be RESTful, we want to preserve the property that a URI that results in a sorted/filtered view always contains the corresponding sorting/filtering parameters. Therefore, if you find that the incoming URI is lacking the right params[] and you're forced to fill them in from the session[], the RESTful thing to do is to redirect_to the new URI containing the appropriate parameters. There is an important corner case to keep in mind here, though: if the previous action had placed a message in the flash[] to display after a redirect to the movies page, your additional redirect will delete that message and it will never appear, since the flash[] only survives across a single redirect. To fix this, use flash.keep right before your additional redirect.

Specific Requirements:

• If the user explicitly includes new sorting/filtering settings in params[], the values stored in the session should not override them. On the contrary, the new settings should be remembered in the session.
• If a user unchecks all checkboxes, use the settings stored in the session[] hash (it doesn't make sense for a user to uncheck all the boxes).