Auto Add Image Title,Caption,Alt Text,Description while uploading Images in WordPress

3 comments

1. added_post_meta seems like a good time to hook into a new image. Not only is the default meta already set but the function gives you the $post_id along with $meta_value which holds the attachment metadata. From there you can get all the fields and set the ones you want.

   add_action('added_post_meta', 'wpse_20151219_after_post_meta', 10, 4);
   
   function wpse_20151219_after_post_meta($meta_id, $post_id, $meta_key, $meta_value) {
   
       // _wp_attachment_metadata added
       if($meta_key === '_wp_attachment_metadata') {
   
           // ----------------------------------------------------------------------
           // POST
           // ----------------------------------------------------------------------
   
           // Change basic fields on attachment post
           wp_update_post(array(
                              'ID'           => $post_id,
                              'post_title'   => "This is a TITLE for $post_id",
                              'post_content' => "This is the DESCRIPTION for $post_id",
                              'post_excerpt' => "This is the CAPTION for $post_id",
                          ));
   
           // ----------------------------------------------------------------------
           // POST META
           // ----------------------------------------------------------------------
   
           // Change ALT Text
           update_post_meta($post_id, '_wp_attachment_image_alt', "This is the ALT Text for $post_id");
   
           // Add Custom Field
           update_post_meta($post_id, '_wpse_20121219_my_custom_meta', 'MyCustomMetaValue');
   
           // ----------------------------------------------------------------------
           // POST META ( ATTACHMENT METADATA )
           // ----------------------------------------------------------------------
   
           // Change Image Metadata
           $meta_value[ 'image_meta' ] = array_merge($meta_value[ 'image_meta' ], array(
               'credit'    => 'https://black-buddha.com',
               'camera'    => 'The Best Camera EVER!',
               'copyright' => date('Y'),
               'title'     => "This is a META TITLE for $post_id",
               'caption'   => "This is a META CAPTION for $post_id",
           ));
   
           // Update The Image Metadata
           wp_update_attachment_metadata($post_id, $meta_value);
   
           // _wp_attached_file
           // _wp_attachment_metadata (serialized)
           // _wp_attachment_image_alt
           // _wpse_20121219_my_custom_meta
   
           $attachment_meta = get_post_meta($post_id);
   
           // width
           // height
           // file
           // sizes
           // image_meta
           //      aperture
           //      credit
           //      camera
           //      caption
           //      created_timestamp
           //      copyright
           //      focal_length
           //      iso
           //      shutter_speed
           //      title
           //      orientation
           //      title
           //      keywords
   
           $attachment_metadata = wp_get_attachment_metadata($post_id);
       }
   }
   

2. You can hook into the ‘add_attachment’ action from wp-includes/post.php Line:3332. (Version 4.4)
   It passes in the post_id and from there you can get the file name and then update the post meta with anything you need to.

   Reference taken from

   add_action( 'add_attachment', 'wpse_125805_add_image_meta_data' );
   
   function wpse_125805_add_image_meta_data( $attachment_ID ) {
   
       $filename   =   $_REQUEST['name']; // or get_post by ID
       $withoutExt =   preg_replace('/\.[^.\s]{3,4}$/', '', $filename);
       $withoutExt =   str_replace(array('-','_'), ' ', $withoutExt);
   
       $my_post = array(
           'ID'           => $attachment_ID,
           'post_excerpt' => $withoutExt,  // caption
           'post_content' => $withoutExt,  // description
       );
       wp_update_post( $my_post );
   
       // update alt text for post
       update_post_meta($attachment_ID, '_wp_attachment_image_alt', $withoutExt );
   }
   

3. For a simpler solution, you can use this WordPress plugin that I made a while back.

   The plugin comes with a bulk updater too that will update the image attributes for images already in your media library if you want to do that as well.

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