File metadata manager

A Drupal module providing a file metadata manager service and API. Allows to get, via an unified API, information stored in files like EXIF photo information, TrueType font information, etc.

Metadata protocols are pluggable. Developers can implement a plugin and use the service framework to get the metadata required.

The following plugins are provided by the module:

The module is inspired by discussions at #2630242 Provide methods to retrieve EXIF image information via the Image object.

Features

1. Load from, and save to, file embedded metadata directly from the files.
2. Metadata for a file is statically cached during a request's lifetime. This avoids different modules all repeat I/O on the same file.
3. Metadata can be cached in a Drupal cache bin to avoid repeating I/O on the files in successive requests.
4. Metadata standards (EXIF, TTF, etc.) are implemented as plugins. The service loads the metadata plugin needed based on the calling code request.
5. Manages copying to/from local temporary storage files stored in remote file systems, to allow PHP functions that do not support remote stream wrappers access the file locally.

Installing

The module requires using Composer to manage Drupal site dependencies. Once you have setup building your code base using composer, require the module via

  $ composer require drupal/file_mdm:^2

then enable the module as usual. Also enable the EXIF or font submodules if needed.

Configuration

• Go to Manage > Configuration > System > File Metadata Manager and specify the cache retention requirements, in general and/or per each metadata plugin.

Usage examples

Metadata are retrieved by specifying the protocol plugin required, and the specific metadata key needed.

For the 'getimagesize' protocol, the metadata keys supported correspond to the array keys returned by the PHP getimagesize() function:

1. Basic usage:

a. Use the FileMetadataManagerInterface::class service to prepare collecting metadata for the file located at a desired URI:

   $fmdm = \Drupal::service(FileMetadataManagerInterface::class);
   $my_file_metadata = $fmdm->uri('public::/my_directory/test-image.jpeg');

b. Get the metadata for the specific protocol, identified by the plugin, and the metadata key required:

   $mime = $my_file_metadata->getMetadata('getimagesize', 'mime');

c. Summarizing, in the context of a controller returning a render array:

  $fmdm = \Drupal::service(FileMetadataManagerInterface::class);
  $my_file_metadata = $fmdm->uri('public::/my_directory/test-image.jpeg');
  $mime = $my_file_metadata->getMetadata('getimagesize', 'mime');
  return ['#markup' => 'MIME type: ' . $mime];

will return something like

MIME type: image/jpeg

2. Use a known local temp copy of the remote file to avoid remote file access:

$fmdm = \Drupal::service(FileMetadataManagerInterface::class);
$my_file_metadata = $fmdm->uri('remote_wrapper::/my_directory/test-image.jpeg');
$my_file_metadata->setLocalTempPath($temp_path);
$mime = $my_file_metadata->getMetadata('getimagesize', 'mime');

3. Make a local temp copy of the remote file to avoid remote file access:

$fmdm = \Drupal::service(FileMetadataManagerInterface::class);
$my_file_metadata = $fmdm->uri('remote_wrapper::/my_directory/test-image.jpeg');
$my_file_metadata->copyUriToTemp();
$mime = $my_file_metadata->getMetadata('getimagesize', 'mime');