Getting attachment ID by URL bug

Hi, I was having difficulty with my images not resizing properly due to the GUID not being the same after changing domains.

I amended your function slightly to the following:

// get attachment ID by image url
function z_get_attachment_id_by_url( $attachment_url = '' ) {
	global $wpdb;
	$attachment_id = false;

	// If there is no url, return.
	if ( '' == $attachment_url )
		return;

	// Get the upload directory paths
	$upload_dir_paths = wp_upload_dir();

	// Make sure the upload path base directory exists in the attachment URL, to verify that we're working with a media library image
	if ( false !== strpos( $attachment_url, $upload_dir_paths['baseurl'] ) ) {

		// If this is the URL of an auto-generated thumbnail, get the URL of the original image
		$attachment_url = preg_replace( '/-\d+x\d+(?=\.(jpg|jpeg|png|gif)$)/i', '', $attachment_url );

		// Remove the upload path base directory from the attachment URL
		$attachment_url = str_replace( $upload_dir_paths['baseurl'] . '/', '', $attachment_url );

		// Finally, run a custom database query to get the attachment ID from the modified attachment URL
		$attachment_id = $wpdb->get_var( $wpdb->prepare( "SELECT wposts.ID FROM $wpdb->posts wposts, $wpdb->postmeta wpostmeta WHERE wposts.ID = wpostmeta.post_id AND wpostmeta.meta_key = '_wp_attached_file' AND wpostmeta.meta_value = '%s' AND wposts.post_type = 'attachment'", $attachment_url ) );

	}

	return $attachment_id;
}

Note: This function is not my own but the work of Philip Newcomer at https://philipnewcomer.net/2012/11/get-the-attachment-id-from-an-image-url-in-wordpress/

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