processing-file-contents-before-writing.md

Processing File Contents Before Writing

Before writing a file to disk, you can perform some actions on its contents. To do this, use the Vinograd\SimpleFiles\Event\FileBeforeWriteListener event listener. It allows you to modify data before storing it in the file system.

📢 Vinograd\SimpleFiles\Event\FileBeforeWriteListener is an interface that allows you to add some logic for processing the contents of a file before writing it to the file system. This interface has a beforeWrite method that is called every time before writing a file.

You can register listeners for a file writing event using the addFileBeforeWriteListener method of an object of the Vinograd\SimpleFiles\File class. This method does not return any values. You need to pass an argument that implements the Vinograd\SimpleFiles\Event\FileBeforeWriteListener interface.

There is no way to control the order in which added listeners are fired other than registering them in the desired order.

beforeWrite Method Overview

The first argument to the beforeWrite method is the file object that is being written. The second is the so-called operation key, which identifies the recording execution context. It can have several values: "WRITE", "WRITE_TO", "COPY" and "MOVE". Using these keys, you can distinguish between file writing execution contexts.

Example of implementation and adding a listener:

<?php
require_once dirname(__DIR__, 1) . '/vendor/autoload.php';

use Vinograd\SimpleFiles\Event\FileBeforeWriteListener;
use Vinograd\SimpleFiles\File;

$file = File::createBinded('path/to/file.txt');
$file->read();
$file->addFileBeforeWriteListener(
    new class() implements FileBeforeWriteListener {
        public function beforeWrite(File $file, string $keyOperation): void
        {
            if ($keyOperation === File::WRITE_TO) {
                $file->setContent('modified ' . $file->getContent());
            }
        }
    }
);
$file->setLocalName('newFile.txt');
$file->writeTo('path/to/new/directory');

To simplify the example, we use an anonymous class that implements the Vinograd\SimpleFiles\Event\FileBeforeWriteListener interface. The beforeWrite method modifies the data being written only if the writeTo method of the Vinograd\SimpleFiles\File object is used.

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