If you have come across a problem with generating a large PDF file in your Laravel application, probably is not a good idea for the user to wait.

One of the solution is to process the PDF generation in background.

Pre-requisite

1. Create a table for cronjob task

Let's name it cronjob table

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<?php
Schema::create('cronjob', function($table) {
$table->increments('id');
$table->string('type', 40);
$table->text('data')->nullable();
$table->integer('user_id')->unsigned()->default(0); // user who created the cron
$table->datetime('executed_at')->nullable(); // the execution start time
$table->datetime('completed_at')->nullable(); // the complete timestamp
});

Don't forget also create a model class, Cronjob.php

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<?php namespace App\Models;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;
class Cronjob extends BaseModel {
use SoftDeletes;
protected $table = 'cronjob';
public function user()
{
return $this->belongsTo('App\Models\User', 'user_id', 'id');
}
}

P/S: In my case, I put all models into app/Models/ directory, it depends on where you keep them

2. Download wkhtmltopdf

Download it here http://wkhtmltopdf.org/downloads.html

Extract the tarball, only copy the binary to your project

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$ mkdir /path/to/project/bin # create a folder to keep the binary
$ mv /path/to/wkhtmltox/bin/wkhtmltopdf /path/to/project/bin/wkhtmltopdf

3. Create a cronjob

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$ crontab -e

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* * * * * /usr/bin/php /path/to/project/artisan schedule:run >> /dev/null 2>&1

Bare in mind that Laravel has it's own scheduler.

Now create a file in /path/to/project/app/Console/Command/GeneratePDF.php

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<?php
namespace App\Console\Commands;
use Illuminate\Console\Command;
use App\Models\Cronjob;
class GeneratePDF extends Command
{
/**
* The name and signature of the console command.
*
* @var string
*/
protected $signature = 'generate_pdf';
/**
* The console command description.
*
* @var string
*/
protected $description = 'Generate pdf from html';
/**
* Execute the console command.
*
* @return mixed
*/
public function handle()
{
// get all cron that not yet complete
$jobs = Cronjob::where('type', $this->signature)
->whereNull('completed_at')
->get();
foreach ($jobs as $job) {
$job->executed_at = date('Y-m-d H:i:s');
$job->save();
$this->_generatePdf($job);
// mark it as completed
$job->completed_at = date('Y-m-d H:i:s');
$job->save();
}
}
protected function _generatePdf(Cronjob $job)
{
$data = json_decode($job->data, 1);
$path = storage_path('files/users/' . $job->user_id . '/pdf');
@mkdir($path, 0755, true);
$html_file = storage_path('files/users/' . $job->user_id . '/html/' . $data['html']);
$file = 'your-awesome-pdf-file.pdf';
$cmd_output = exec(base_path('bin/wkhtmltopdf') . ' ' . $html_file . ' ' . $path . '/' . $file);
unlink($html_file); // remove temporary html file
}
}

Also, don't forget to add it to /path/to/project/app/Console/Kernel.php

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<?php
protected $commands = [
...
\App\Console\Commands\GeneratePDF::class,
];
...
protected function schedule(Schedule $schedule)
{
...
$schedule->command('generate_pdf')
->everyMinute()
->withoutOverlapping()
->sendOutputTo(storage_path('logs/generate_pdf.log'))
;
}

Now it will run this every minute.

4. In your controller

Now let's do the code in your controller

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<?php
public function generatePDF(Request $request)
{
...
$html = view('module.awesome.pdf', [
'data' => $data,
])->render();
$path = storage_path('files/users/' . \Auth::user()->id . '/html');
@mkdir($path, 0755, true);
$filename = 'awesome-html-file.html';
file_put_contents($path . '/' . $filename, $html); // save to a temporary html file
// schedule generate pdf in cronjob
$cronjob = new Cronjob();
$cronjob->type = 'generate_pdf';
$cronjob->data = json_encode([
'html' => $filename,
]);
$cronjob->user_id = \Auth::user()->id; // keep the current user identity, because in cron, it won't know which user is current user
$cronjob->save();
return redirect()->back()
->with('alert.success', 'PDF is currently processing in background. Please refresh the page later.');
}

DONE :)