Working with MIME Types

Installation

The Mime component is already installed in applications that use the Mailer. In any other application, run this command to install it:

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$ composer require symfony/mime

Converting MIME Types into File Extensions

The MimeTypes class transforms between MIME types and file name extensions. In Symfony applications, inject this object in your services using the MimeTypesInterface type-hint; in any other application, create it yourself:

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// src/Service/SomeService.php
namespace App\Service;

use Symfony\Component\Mime\MimeTypesInterface;

class SomeService
{
    public function __construct(
        private MimeTypesInterface $mimeTypes,
    ) {
    }

    // ...
}

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use Symfony\Component\Mime\MimeTypes;

$mimeTypes = new MimeTypes();

Use the getExtensions() and getMimeTypes() methods to transform between MIME types and file name extensions:

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$exts = $mimeTypes->getExtensions('application/javascript');
// $exts = ['js', 'jsm', 'mjs']
$exts = $mimeTypes->getExtensions('image/jpeg');
// $exts = ['jpeg', 'jpg', 'jpe']

$types = $mimeTypes->getMimeTypes('js');
// $types = ['application/javascript', 'application/x-javascript', 'text/javascript']
$types = $mimeTypes->getMimeTypes('apk');
// $types = ['application/vnd.android.package-archive']

These methods return arrays with one or more elements. The element position indicates its priority, so the first returned extension is the preferred one.

Guessing the MIME Type of a File

Another useful utility lets you guess the MIME type of any given file:

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$mimeType = $mimeTypes->guessMimeType('/some/path/to/image.gif');
// Guessing is not based on the file name, so $mimeType will be 'image/gif'
// only if the given file is truly a GIF image

Guessing the MIME type is a time-consuming process that requires inspecting part of the file contents. Symfony applies multiple guessing mechanisms, one of them based on the PHP fileinfo extension. It's recommended to install that extension to improve the guessing performance.

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namespace App;

use Symfony\Component\Mime\MimeTypeGuesserInterface;

class SomeMimeTypeGuesser implements MimeTypeGuesserInterface
{
    public function isGuesserSupported(): bool
    {
        // return true when the guesser is supported (might depend on the OS for instance)
        return true;
    }

    public function guessMimeType(string $path): ?string
    {
        // inspect the contents of the file stored in $path to guess its
        // type and return a valid MIME type ... or null if unknown

        return '...';
    }
}

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$mimeTypes->registerGuesser(new SomeMimeTypeGuesser());