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

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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.

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