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Dictionaries

So far, we have been working with data where an episode is represented as a list. But we have seen that some data may be missing. Imagine that we might have the production year listed in the fifth position; when the “watched/not watched” information is missing, this can be unmanageable:

episode_not_viewed = ["The new Project", 1, 98, 0]
episode_not_viewed = ['Installing the softwares', 2, 42]
episode_not_viewed_with_year = ["The new Project", 1, 98, 0, 2026]
episode_not_viewed_with_year = ['Installing the softwares', 2, 42, 2026]
In some cases, such as when reading CSV files or querying databases, data is represented as a list. At that time, we still have information about the columns. This structure is “impractical” for managing the data.

We will work with data structured as dictionaries. The data has been loaded in list form by a parser that knows the source and will transform it into a dictionary.

The data structure will be as follows:

{"title": "The Conjugal Configuration",
 "duration": 20,
 "viewed": 0}

Working Files

In a real-world scenario, we would be updating the code to replace the contents of exos/base/media_utils.py with a solution using dictionaries. For the purposes of this training, to preserve the exercises you’ve completed, rename this file to exos/base/media_utils_legacy.py, along with the associated tests. Don’t forget to update the imports if your IDE doesn’t do this for you.

Exercises

Getting Started with Dictionaries

Start by getting familiar with this data. Copy this data into an interactive shell or a draft script to perform a few actions:

  • Display the title.
  • Change its status (it should become “viewed”) and display the data. Although the “viewed/unviewed” status is a boolean, anticipate that it could be something else.

A function for the status

An unviewed episode has the viewed key associated with the value False or does not have this key. Try to determine how to handle this situation.

In the exos/base/media_utils.py module, write a function is_viewed(episode: dict) that takes a dictionary as a parameter and returns True if the episode has been viewed, otherwise False. Feel free to use a test-first approach to write this function using the available data.

Here are two examples of data that provide the test cases.

Viewed episodes:

{"title": "The Conjugal Configuration", "duration": 20, "viewed": True}
{"title": "The Conjugal Configuration", "duration": 20, "viewed": 3}
{"title": "The Conjugal Configuration", "duration": 20, "viewed": 3, "year": 2019}

Not viewed episodes:

{"title": "The Conjugal Configuration", "duration": 20, "viewed": False}
{"title": "The Conjugal Configuration", "duration": 20, "viewed": 0}
{"title": "The Conjugal Configuration", "duration": 20}
{"title": "The Conjugal Configuration", "duration": 20, "year":2018}