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Learn how to efficiently count related data in Laravel Eloquent, focusing on calculating total income for products in a shop over the last 30 days.
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Counting Related Data with Laravel Eloquent

When working with a Laravel application, you may run into scenarios where you need to perform complex queries that involve relations between different models. One common issue that developers face is how to count some related data while fetching records from the database. In this post, we'll break down a specific problem: how to calculate the total income from products sold in a shop using Laravel Eloquent.

The Problem Statement

Imagine you have a Product model with associated OrderItem entries. Each product can have multiple order items pointing to it, which contain details such as sell price and quantity sold. Now, suppose you want to retrieve all products for a given shop and calculate two things:

The total income generated from each product (which is the sum of sell_price * sold_quantity).

The income generated from the same products over the last 30 days.

Let's explore how to accomplish this efficiently using Laravel's query builder and Eloquent relationships.

The Solution: A Step-by-Step Approach

To tackle this problem, we'll use a combination of joins, conditional checks, and raw SQL queries to gather the necessary data. Here’s how you can achieve this:

Step 1: Understanding the Structure

Before diving into the code, let’s ensure we are clear about the structure of our tables:

Products Table:

id

name (title)

shop_id

OrderItems Table:

id

product_id (foreign key)

sell_price

sold_quantity

created_at (date of sale)

Step 2: Writing the Query

We'll make use of Laravel's query builder to join the products and orderItems tables. Here’s how you can structure your query:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Explaining the Code

Table Joins: We start by joining the products table with the orderItems table. This allows us to access related order information for each product.

Filtering Data: We use where to specify that we only want products belonging to a particular shop and use whereDate to limit the results to order items created within the last 30 days.

Calculating Totals:

The selectRaw function allows us to calculate the total income for the products based on the product's sell price and the quantity sold.

We also calculate a grand_total, which sums the income for all time for each product.

Grouping Results: Finally, we group our results by the product id and name to get a unique record for each product.

Conclusion

By following this structured approach, you can efficiently retrieve and calculate the income generated from products sold in a shop using Laravel Eloquent. This allows for cleaner and more maintainable code while leveraging the powerful capabilities of Laravel's query builder.

Feel free to adapt the query to your specific needs, and happy coding!