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attachment_url_to_postid()

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概述

attachment_url_to_postid() 函数用于将附件 URL 转换为对应的文章 ID。它通过查询数据库中的 _wp_attached_file 元数据来实现，并支持过滤器钩子进行自定义处理。

关键要点

  • 参数：接受一个字符串类型的 URL 参数，必需。
  • 返回值：成功时返回附件对应的文章 ID（整数），失败时返回 0。
  • 核心机制：基于上传目录路径解析 URL，查询 postmeta 表匹配 _wp_attached_file 元值。
  • 过滤器钩子：提供 pre_attachment_url_to_postid 和 attachment_url_to_postid 钩子，允许插件干预查找过程。
  • 注意事项：使用 === 运算符测试过滤器返回的 post ID，以避免类型转换问题。

代码示例

$attachment_url = 'https://example.com/wp-content/uploads/2023/09/image.jpg';
$attachment_post_id = attachment_url_to_postid( esc_url( $attachment_url ) );

if ( 0 !== $attachment_post_id ) {
    // 找到附件文章或页面
    printf( esc_html__( 'Attachment is associated with post ID: %s', 'textdomain' ),
        $attachment_post_id
    );
} else {
    // 未找到对应附件
    esc_html_e( 'No post or page found for the provided attachment URL.', 'textdomain' );
}
📄 原文内容

Tries to convert an attachment URL into a post ID.

Parameters

$urlstringrequired
The URL to resolve.

Return

int The found post ID, or 0 on failure.

Source

function attachment_url_to_postid( $url ) {
	global $wpdb;

	/**
	 * Filters the attachment ID to allow short-circuit the function.
	 *
	 * Allows plugins to short-circuit attachment ID lookups. Plugins making
	 * use of this function should return:
	 *
	 * - 0 (integer) to indicate the attachment is not found,
	 * - attachment ID (integer) to indicate the attachment ID found,
	 * - null to indicate WordPress should proceed with the lookup.
	 *
	 * Warning: The post ID may be null or zero, both of which cast to a
	 * boolean false. For information about casting to booleans see the
	 * <a href="https://www.php.net/manual/en/language.types.boolean.php/">PHP documentation</a>.
	 * Use the === operator for testing the post ID when developing filters using
	 * this hook.
	 *
	 * @since 6.7.0
	 *
	 * @param int|null $post_id The result of the post ID lookup. Null to indicate
	 *                          no lookup has been attempted. Default null.
	 * @param string   $url     The URL being looked up.
	 */
	$post_id = apply_filters( 'pre_attachment_url_to_postid', null, $url );
	if ( null !== $post_id ) {
		return (int) $post_id;
	}

	$dir  = wp_get_upload_dir();
	$path = $url;

	$site_url   = parse_url( $dir['url'] );
	$image_path = parse_url( $path );

	// Force the protocols to match if needed.
	if ( isset( $image_path['scheme'] ) && ( $image_path['scheme'] !== $site_url['scheme'] ) ) {
		$path = str_replace( $image_path['scheme'], $site_url['scheme'], $path );
	}

	if ( str_starts_with( $path, $dir['baseurl'] . '/' ) ) {
		$path = substr( $path, strlen( $dir['baseurl'] . '/' ) );
	}

	$sql = $wpdb->prepare(
		"SELECT post_id, meta_value FROM $wpdb->postmeta WHERE meta_key = '_wp_attached_file' AND meta_value = %s",
		$path
	);

	$results = $wpdb->get_results( $sql );
	$post_id = null;

	if ( $results ) {
		// Use the first available result, but prefer a case-sensitive match, if exists.
		$post_id = reset( $results )->post_id;

		if ( count( $results ) > 1 ) {
			foreach ( $results as $result ) {
				if ( $path === $result->meta_value ) {
					$post_id = $result->post_id;
					break;
				}
			}
		}
	}

	/**
	 * Filters an attachment ID found by URL.
	 *
	 * @since 4.2.0
	 *
	 * @param int|null $post_id The post_id (if any) found by the function.
	 * @param string   $url     The URL being looked up.
	 */
	return (int) apply_filters( 'attachment_url_to_postid', $post_id, $url );
}

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Hooks

apply_filters( ‘attachment_url_to_postid’, int|null $post_id, string $url )

Filters an attachment ID found by URL.

apply_filters( ‘pre_attachment_url_to_postid’, int|null $post_id, string $url )

Filters the attachment ID to allow short-circuit the function.

Uses Description
wp_get_upload_dir()wp-includes/functions.php

Retrieves uploads directory information.
apply_filters()wp-includes/plugin.php

Calls the callback functions that have been added to a filter hook.
wpdb::get_results()wp-includes/class-wpdb.php

Retrieves an entire SQL result set from the database (i.e., many rows).
wpdb::prepare()wp-includes/class-wpdb.php

Prepares a SQL query for safe execution.

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Used by Description
wp_ajax_set_attachment_thumbnail()wp-admin/includes/ajax-actions.php

Handles setting the featured image for an attachment via AJAX.
WP_Customize_Upload_Control::to_json()wp-includes/customize/class-wp-customize-upload-control.php

Refresh the parameters passed to the JavaScript via JSON.

Changelog

Version Description
4.0.0 Introduced.

User Contributed Notes

  2. Skip to note 4 content


    Milana Cap


    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

    Applying WordPress coding standards and best practices, example should look like this, Muhibul.

    $attachment_url     = 'https://example.com/wp-content/uploads/2023/09/image.jpg';
$attachment_post_id = attachment_url_to_postid( esc_url( $attachment_url ) );

if ( 0 !== $attachment_post_id ) {
    // An attachment post or page was found.
    printf( esc_html__( 'Attachment is associated with post ID: %s', 'textdomain'),
        $attachment_post_id
    );
} else {
    // No attachment post or page found for the URL.
    esc_html_e( 'No post or page found for the provided attachment URL.', 'textdomain');
}