Hello, and welcome to today's lesson! Today, we are going to dive into the world of managing product reviews and applying data aggregation in practice. We will start with a relatively simple Starter Task to set up our base and then gradually build up to a more complex solution involving data aggregation. Let's jump in!

For our starter task, we will lay the foundation by implementing basic operations for managing product reviews. We will be using classes to encapsulate the details of a product review. Our Review class will consist of the following properties:

• $text — The textual content of the review.
• $rating — The rating score of the review, ranging from 1 to 5.
• $flagged — A boolean indicating whether the review is flagged as inappropriate.

These are the methods we will implement in a ReviewManager class:

• addReview($productId, $reviewId, $reviewText, $rating) — Adds a review to the product specified by $productId. If a review with $reviewId already exists, it updates the existing review. Returns true if the review was added or updated successfully, false otherwise. For newly added items, the $flagged attribute is set to false initially.

• getReview($productId, $reviewId) — Returns the review details ($text, , and fields) for the review specified by under the given . If the review or product does not exist, returns .

Let's look at the code that implements these functionalities in PHP:

This code establishes the foundational methods needed for managing product reviews within a ReviewManager class. The addReview method allows for adding a new review or updating an existing one, ensuring each review contains valid rating values between 1 and 5. The getReview method retrieves the review details for a specific product, including the review text and rating, returning if the product or review doesn't exist. The method facilitates the removal of a specific review, and if no reviews are left for a product, the product itself is removed from the product list. Together, these methods form the basic operations required to manage a collection of product reviews efficiently.

With our basic review management system in place, we will now introduce new methods to handle more complex operations, such as flagging inappropriate reviews and aggregating review data for a specific product.

Here are the new methods we will add:

• flagReview($productId, $reviewId) — This method flags a specific review as inappropriate for a given product. Returns true if the review was successfully flagged, false otherwise.

• aggregateReviews($productId) — This method aggregates review data for a given product, providing statistics such as the total number of reviews, the number of flagged reviews, average rating, and review texts excluding flagged ones. If the product does not have any reviews or does not exist, returns null.

First, let's add functionality to flag a review:

In this step, we are adding the flagReview method to our ReviewManager class. This method enables users to mark a specific review as inappropriate. It checks whether the product and review exist in the dataset, and if they do, it sets the flagged attribute of the review to true. This flagging mechanism is crucial for maintaining the quality and appropriateness of the reviews in the system.

Next, we will implement the method to aggregate reviews:

Great job! Today, you have learned how to manage product reviews and apply data aggregation in practice using PHP. We started with basic operations for adding, retrieving, and deleting reviews. Then, we extended our functionality to include flagging reviews and aggregating review data. This gradual build-up demonstrates how to enhance features incrementally and handle more complex data aggregation tasks.

Feel free to practice solving similar challenges to strengthen your skills further. Keep coding, and see you in the next lesson!