Movie Watchlist Code-Along

Currently, there is a program that tracks movies a person wants to watch. It works pretty well, but there are some improvements to be made in the code. Refactor the program so that it uses a Movie class, and tracks one List of Movie objects instead of two lists.

Note that the goal of this exercise is NOT to change the functionality of the application; it should still work in the same way. The goal is to improve the architecture, to make it easier to maintain.

The Current App

Visit the Repl for the app so far, and try to figure out how it works. There are a few important features:

• Two Lists: one that stores movie titles, and one that stores movie release years
• A while loop that infinitely displays the menu for the application
• An "Add Movie" command that adds a movie title and year to the respective Lists
• A "View Movies" command that displays information about each movie

So, what's wrong with the way it works now? It seems to be functioning properly, but it could be organized in a simpler way. Separating some code into another class makes it easier to separate concerns for the app, and it also makes it easier to add features. The way it currently works, with two separate lists, is a little fragile. If those lists somehow become desynchronized, the data would not match up. Additionally, a whole new list would have to be created to store an additional piece of information about a movie (e.g. its rating, its Rotten Tomatoes score, or anything else). For these reasons, it makes a lot of sense to create a new class!

Here is the plan:

1. Create a class named Movie
2. Add a Title and Year field to the Movie class
3. Update the main code so that it creates a List of Movie objects instead of two separate lists
4. Update the adding code so that it creates a new Movie object, sets the fields properly, and adds it to the list
5. Add a method on the Movie class to print out a movie in the proper format
6. Update the viewing code so that it uses a foreach loop to go through each Movie object and print it

Let's get started!

Creating the Movie Class

Create a new file in the current folder named Movie.cs. This file will contain the Movie class.

1. At the top of the file, add using System;
2. Under that, define the Movie class with public class Movie {}
3. What should the Movie class contain? What pieces of data are stored for each movie? So far, the app stores a title, and a year. Add those as fields for the movie

Movie.cs

using System;

public class Movie
{
    public string Title;
    public int Year;
}

That's all that's needed to start working with the Movie class and creating Movie objects.

Using the Movie Type: Adding Movie Objects

Consolidate the two Lists that store movie information into one: a List of Movie objects!

First, remove the two existing List variables, and create a new List<Movie> named movies. Everything looks the same as any other List, only with Movie as the type:

List<Movie> movies = new List<Movie>();

Next, when adding a movie, update the code so that it creates a new Movie object. For the new Movie object, set the Title and Year fields to be whatever the user entered, and add the new movie to the movies list.

Movie movie = new Movie();
movie.Title = newTitle;
movie.Year = Convert.ToInt32(newYear);

movies.Add(movie);

For now, comment out the for loop code for viewing movies so the code will work without an error. Run the program, and make sure movies can be added! Obviously, adding movies doesn't do much good if they cannot be viewed.

Using the Movie Type: Viewing Movie Objects

Before, the code used a for loop and printed out the title and year from the separate lists. Now that the Movie class exists, the actual printing can be done there instead! This helps separate concerns, and makes the code easier to read.

In the Movie.cs file, add a new method named Print to the Movie class. It should be public, and have a return type of void:

public void Print()
{

}

Note that there is no static keyword used! This is because this method will use the fields on the class. Copy the code from the original for loop into the body of the method, and update the variable names so that they use the fields instead:

Console.WriteLine($"{Title} ({Year})");

Now, find the "View Movies" code where the for loop is commented out. Remove the for loop, and replace it with a foreach loop. This should loop through each Movie object in the movies list:

foreach (Movie m in movies)
{

}

In the body of the foreach loop, all that's needed is to call the Print method on the current Movie!

m.Print();

Run the program, and verify that the current movie watchlist can be viewed!

Adding a Rating field

To illustrate the usefulness of classes, add an additional field to the Movie class: Rating.

1. In the Movie.cs file, add a new public string field to the Movie class
2. In the Print method, update the message so that it includes the Rating value
3. In the main.cs file, when adding a movie, ask the user for a rating
4. Set the Rating property on the new Movie object to reflect what the user entered

That's all that's needed! The "View Movies" code does not need to be updated, and a new List does not need to be created. This makes the Movie Watchlist application much easier to maintain!