fetch_feed()
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概述
fetch_feed() 函数用于基于 RSS 或 Atom 源 URL 构建 SimplePie 对象,支持单 URL 或 URL 数组以合并多个源。默认缓存 12 小时,可通过过滤器调整。
关键要点
- 参数 $url 可为字符串或字符串数组,数组时使用 SimplePie 多源功能合并
- 返回 SimplePie 对象或 WP_Error 对象,处理错误时返回 WP_Error
- 缓存时间可通过 wp_feed_cache_transient_lifetime 过滤器修改,默认 12 小时
- 内部注册自定义缓存、文件和清理类,确保与 WordPress 集成
- 支持 wp_feed_options 动作钩子,在处理前修改 SimplePie 对象
代码示例
// 示例:获取并显示 RSS 源的前 5 个条目链接
$rss = fetch_feed('http://example.com/feed');
if (!is_wp_error($rss)) {
$maxitems = $rss->get_item_quantity(5);
$rss_items = $rss->get_items(0, $maxitems);
foreach ($rss_items as $item) {
echo '<a href="' . esc_url($item->get_permalink()) . '" title="' . esc_attr($item->get_date('j F Y | g:i a')) . '">' . esc_html($item->get_title()) . '</a>';
}
}注意事项
- 无需手动包含 feed.php,函数随 WordPress 自动加载
- 空 URL 或数组处理有特殊逻辑,避免 PHP 8.5 弃用问题
- 使用 SimplePie 1.3 或更高版本时推荐缓存注册方法,否则回退到兼容方式
原文内容
Builds SimplePie object based on RSS or Atom feed from URL.
Parameters
$urlstring|string[]required-
URL of feed to retrieve. If an array of URLs, the feeds are merged using SimplePie’s multifeed feature.
See also http://simplepie.org/wiki/faq/typical_multifeed_gotchas
Source
function fetch_feed( $url ) {
if ( ! class_exists( 'SimplePieSimplePie', false ) ) {
require_once ABSPATH . WPINC . '/class-simplepie.php';
}
require_once ABSPATH . WPINC . '/class-wp-feed-cache-transient.php';
require_once ABSPATH . WPINC . '/class-wp-simplepie-file.php';
require_once ABSPATH . WPINC . '/class-wp-simplepie-sanitize-kses.php';
$feed = new SimplePieSimplePie();
$feed->get_registry()->register( SimplePieSanitize::class, 'WP_SimplePie_Sanitize_KSES', true );
/*
* We must manually overwrite $feed->sanitize because SimplePie's constructor
* sets it before we have a chance to set the sanitization class.
*/
$feed->sanitize = new WP_SimplePie_Sanitize_KSES();
// Register the cache handler using the recommended method for SimplePie 1.3 or later.
if ( method_exists( 'SimplePie_Cache', 'register' ) ) {
SimplePie_Cache::register( 'wp_transient', 'WP_Feed_Cache_Transient' );
$feed->set_cache_location( 'wp_transient' );
} else {
// Back-compat for SimplePie 1.2.x.
require_once ABSPATH . WPINC . '/class-wp-feed-cache.php';
$feed->set_cache_class( 'WP_Feed_Cache' );
}
$feed->get_registry()->register( SimplePieFile::class, 'WP_SimplePie_File', true );
/** This filter is documented in wp-includes/class-wp-feed-cache-transient.php */
$feed->set_cache_duration( apply_filters( 'wp_feed_cache_transient_lifetime', 12 * HOUR_IN_SECONDS, $url ) );
/**
* Fires just before processing the SimplePie feed object.
*
* @since 3.0.0
*
* @param SimplePieSimplePie $feed SimplePie feed object (passed by reference).
* @param string|string[] $url URL of feed or array of URLs of feeds to retrieve.
*/
do_action_ref_array( 'wp_feed_options', array( &$feed, $url ) );
if ( empty( $url ) ) {
/*
* @todo: Set $url to empty string once supported by SimplePie.
*
* The early return without proceeding is to work around a PHP 8.5
* deprecation issue resolved in https://github.com/simplepie/simplepie/pull/949
*
* To avoid the duplicate code, this block can be replaced with `$url = '';` once SimplePie
* is upgraded to a version that includes the fix.
*/
$feed->init();
$feed->set_output_encoding( get_bloginfo( 'charset' ) );
if ( $feed->error() ) {
return new WP_Error( 'simplepie-error', $feed->error() );
}
return $feed;
} elseif ( is_array( $url ) && count( $url ) === 1 ) {
$url = array_shift( $url );
} elseif ( is_array( $url ) ) {
$feeds = array();
$simplepie_errors = array();
foreach ( $url as $feed_url ) {
$simplepie_instance = clone $feed;
$simplepie_instance->set_feed_url( $feed_url );
$simplepie_instance->init();
$simplepie_instance->set_output_encoding( get_bloginfo( 'charset' ) );
if ( $simplepie_instance->error() ) {
$simplepie_errors[] = sprintf(
/* translators: %1$s is the feed URL, %2$s is the error message. */
__( 'Error fetching feed %1$s: %2$s' ),
esc_url( $feed_url ),
$simplepie_instance->error()
);
unset( $simplepie_instance );
continue;
}
$feeds[] = $simplepie_instance;
unset( $simplepie_instance );
}
if ( ! empty( $simplepie_errors ) ) {
return new WP_Error( 'simplepie-error', $simplepie_errors );
}
$feed->init();
$feed->data['items'] = SimplePieSimplePie::merge_items( $feeds );
return $feed;
}
$feed->set_feed_url( $url );
$feed->init();
$feed->set_output_encoding( get_bloginfo( 'charset' ) );
if ( $feed->error() ) {
return new WP_Error( 'simplepie-error', $feed->error() );
}
return $feed;
}
Hooks
- apply_filters( ‘wp_feed_cache_transient_lifetime’, int $lifetime, string $name )
-
Filters the transient lifetime of the feed cache.
- do_action_ref_array( ‘wp_feed_options’, SimplePieSimplePie $feed, string|string[] $url )
-
Fires just before processing the SimplePie feed object.
Changelog
| Version | Description |
|---|---|
| 2.8.0 | Introduced. |
Skip to note 2 content
Codex
Example
This example will retrieve and display a list of links for an existing RSS feed, limiting the selection to the five most recent items:
<h2></h2> get_item_quantity( 5 ); // Build an array of all the items, starting with element 0 (first element). $rss_items = $rss->get_items( 0, $maxitems ); endif; ?> <ul> <li></li> <li> <a href="<?php echo esc_url( $item->get_permalink() ); ?>" title="<?php printf( __( 'Posted %s', 'wpdocs_textdomain' ), $item->get_date('j F Y | g:i a') ); ?>"> get_title() ); ?> </a> </li> </ul>