Question

wp_get_attachment_url( int $post_id )

Retrieve the URL for an attachment.

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description

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参数

$post_id

(int) (Optional) Attachment ID. Default 0.

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返回值

(string|false) Attachment URL, otherwise false.

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源代码

File: wp-includes/post.php

function wp_get_attachment_url( $post_id = 0 ) {
	$post_id = (int) $post_id;
	if ( !$post = get_post( $post_id ) )
		return false;

	if ( 'attachment' != $post->post_type )
		return false;

	$url = '';
	// Get attached file.
	if ( $file = get_post_meta( $post->ID, '_wp_attached_file', true ) ) {
		// Get upload directory.
		if ( ( $uploads = wp_get_upload_dir() ) && false === $uploads['error'] ) {
			// Check that the upload base exists in the file location.
			if ( 0 === strpos( $file, $uploads['basedir'] ) ) {
				// Replace file location with url location.
				$url = str_replace($uploads['basedir'], $uploads['baseurl'], $file);
			} elseif ( false !== strpos($file, 'wp-content/uploads') ) {
				// Get the directory name relative to the basedir (back compat for pre-2.7 uploads)
				$url = trailingslashit( $uploads['baseurl'] . '/' . _wp_get_attachment_relative_path( $file ) ) . basename( $file );
			} else {
				// It's a newly-uploaded file, therefore $file is relative to the basedir.
				$url = $uploads['baseurl'] . "/$file";
			}
		}
	}

	/*
	 * If any of the above options failed, Fallback on the GUID as used pre-2.7,
	 * not recommended to rely upon this.
	 */
	if ( empty($url) ) {
		$url = get_the_guid( $post->ID );
	}

	// On SSL front end, URLs should be HTTPS.
	if ( is_ssl() && ! is_admin() && 'wp-login.php' !== $GLOBALS['pagenow'] ) {
		$url = set_url_scheme( $url );
	}

	/**
	 * Filters the attachment URL.
	 *
	 * @since 2.1.0
	 *
	 * @param string $url     URL for the given attachment.
	 * @param int    $post_id Attachment ID.
	 */
	$url = apply_filters( 'wp_get_attachment_url', $url, $post->ID );

	if ( empty( $url ) )
		return false;

	return $url;
}

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更新日志

Version	description
2.1.0	Introduced.

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相关函数

Uses

• wp-includes/functions.php: wp_get_upload_dir()
• wp-includes/media.php: _wp_get_attachment_relative_path()
• wp-includes/formatting.php: trailingslashit()
• wp-includes/load.php: is_admin()
• wp-includes/load.php: is_ssl()
• wp-includes/link-template.php: set_url_scheme()
• wp-includes/plugin.php: apply_filters()
• wp-includes/post-template.php: get_the_guid()
• wp-includes/post.php: wp_get_attachment_url
• wp-includes/post.php: get_post_meta()
• wp-includes/post.php: get_post()
Show 6 more uses Hide more uses

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Used By

• wp-includes/widgets/class-wp-widget-media-audio.php: WP_Widget_Media_Audio::render_media()
• wp-includes/widgets/class-wp-widget-media-video.php: WP_Widget_Media_Video::render_media()
• wp-includes/widgets/class-wp-widget-media-image.php: WP_Widget_Media_Image::render_media()
• wp-includes/class-wp-customize-manager.php: WP_Customize_Manager::import_theme_starter_content()
• wp-includes/theme.php: get_header_video_url()
• wp-includes/rest-api/endpoints/class-wp-rest-attachments-controller.php: WP_REST_Attachments_Controller::prepare_item_for_response()
• wp-admin/includes/class-wp-site-icon.php: WP_Site_Icon::create_attachment_object()
• wp-admin/includes/ajax-actions.php: wp_ajax_crop_image()
• wp-admin/includes/export.php: export_wp()
• wp-admin/includes/image-edit.php: wp_save_image()
• wp-admin/includes/image.php: _load_image_to_edit_path()
• wp-admin/includes/template.php: _media_states()
• wp-admin/includes/media.php: edit_form_image_editor()
• wp-admin/includes/media.php: attachment_submitbox_metadata()
• wp-admin/includes/media.php: get_attachment_fields_to_edit()
• wp-admin/includes/media.php: media_sideload_image()
• wp-admin/includes/media.php: image_link_input_fields()
• wp-admin/custom-header.php: Custom_Image_Header::create_attachment_object()
• wp-admin/custom-header.php: Custom_Image_Header::ajax_header_crop()
• wp-admin/custom-header.php: Custom_Image_Header::step_3()
• wp-includes/theme.php: _delete_attachment_theme_mod()
• wp-includes/theme.php: get_uploaded_header_images()
• wp-includes/deprecated.php: get_the_attachment_link()
• wp-includes/deprecated.php: get_attachment_icon_src()
• wp-includes/post-template.php: wp_get_attachment_link()
• wp-includes/post-template.php: prepend_attachment()
• wp-includes/media.php: wp_prepare_attachment_for_js()
• wp-includes/media.php: wp_video_shortcode()
• wp-includes/media.php: wp_playlist_shortcode()
• wp-includes/media.php: wp_audio_shortcode()
• wp-includes/media.php: image_get_intermediate_size()
• wp-includes/media.php: image_downsize()
• wp-includes/post.php: wp_get_attachment_thumb_url()
• wp-includes/class-wp-xmlrpc-server.php: wp_xmlrpc_server::_prepare_media_item()
Show 29 more used by Hide more used by

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User Contributed Notes

1. Skip to note content You must log in to vote on the helpfulness of this noteVote results for this note: 0You must log in to vote on the helpfulness of this note Contributed by Codex

   Basic Example

   
   <?php echo wp_get_attachment_url( 12 ); ?> 
   

   Outputs something like http://example.net/wp-content/uploads/filename

Use Post Thumbnail as Background Image

if ( have_posts() ) : while ( have_posts() ) : the_post(); 
    if ( has_post_thumbnail() ) {
        $feat_image_url = wp_get_attachment_url( get_post_thumbnail_id() );
        echo '<div style="background-image:url('.$feat_image_url.');"></div>';
    }
    endwhile;
endif;