php 47 lines · 8 steps

Streaming a monthly revenue CSV in Laravel

A report service builds a revenue CSV by lazily streaming completed orders, tallying a running total, and writing the file to disk.

Explained by highlit

Laravel Intermediate csv-export lazy-collections eloquent-query memory-efficiency aggregation

1<?php
2 
3namespace App\Services\Reports;
4 
5use App\Models\Order;
6use Illuminate\Support\Facades\Storage;
7use League\Csv\Writer;
8 
9class MonthlyRevenueReport
10{
11    public function generate(string $month): string
12    {
13        $path = "reports/revenue-{$month}.csv";
14        $csv = Writer::createFromString();
15        $csv->insertOne(['order_id', 'customer', 'placed_at', 'net_total', 'tax', 'gross_total']);
16 
17        $grossRunningTotal = 0;
18 
19        Order::query()
20            ->whereYear('placed_at', substr($month, 0, 4))
21            ->whereMonth('placed_at', substr($month, 5, 2))
22            ->where('status', 'completed')
23            ->with('customer:id,name')
24            ->orderBy('placed_at')
25            ->lazy(1000)
26            ->each(function (Order $order) use ($csv, &$grossRunningTotal): void {
27                $tax = round($order->net_total * $order->tax_rate, 2);
28                $gross = $order->net_total + $tax;
29                $grossRunningTotal += $gross;
30 
31                $csv->insertOne([
32                    $order->id,
33                    $order->customer->name,
34                    $order->placed_at->toDateTimeString(),
35                    number_format($order->net_total, 2, '.', ''),
36                    number_format($tax, 2, '.', ''),
37                    number_format($gross, 2, '.', ''),
38                ]);
39            });
40 
41        $csv->insertOne(['', '', '', '', 'TOTAL', number_format($grossRunningTotal, 2, '.', '')]);
42 
43        Storage::disk('reports')->put($path, $csv->toString());
44 
45        return $path;
46    }
47}

01 / 01

STEP 01

Walkthrough

Space play ←→ step click any line

Three takeaways

1Lazy collections let you process large query results in chunks without loading every row into memory at once.
2Accumulating a total by reference inside the iteration callback avoids a second pass over the data.
3Eager-loading and column selection on relations keep per-row work cheap during a big export.

Related explainers

php

<?php
 
class NameParser
{

Parsing a full name into components in PHP

string-parsing arrays normalization

Intermediate 8 steps

php

<?php
 
namespace App\Services\Checkout;

Validating coupons with Laravel's Pipeline

pipeline chain of responsibility transactions

Intermediate 7 steps

php

<?php
 
namespace App\Services;

How a password strength validator works in PHP

validation regular-expressions data-driven

Intermediate 8 steps

ruby

class LogAggregator
  BUCKET_FORMAT = "%Y-%m-%dT%H:%M"
 
  def initialize(entries)

Bucketing log entries by the minute in Ruby

aggregation hashing enumerable

Intermediate 5 steps

ruby

class WeeklySignupsReport
  DEFAULT_WEEKS = 12
 
  def initialize(weeks: DEFAULT_WEEKS, source: User.all)

Building a weekly signups report in Rails

service object aggregation group by

Intermediate 7 steps

php

<?php
 
namespace App\Services;

Building a cached daily leaderboard in Laravel

caching aggregation eager-loading

Intermediate 9 steps

Share this explainer

Here's the card — post it anywhere.

Streaming a monthly revenue CSV in Laravel — share card

Made with highlit — turn any snippet into a walkthrough like this in about a minute.

Explain your code