Handle multiple feeds in `fetch_feed()`. by peterwilsoncc · Pull Request #10631 · WordPress/wordpress-develop

peterwilsoncc · 2025-12-15T03:33:35Z

Handles passing an array to fetch_feed() by requesting each feed individually and then calling SimplePie\SimplePie::merge_items(); on the result before passing the data back in to a SimplePie object.

I don't love this so would love some suggestions of anything I am missing.

Trac ticket: https://core.trac.wordpress.org/ticket/64136

This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

github-actions · 2025-12-15T03:33:45Z

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Core Committers: Use this line as a base for the props when committing in SVN:

Props peterwilsoncc, wildworks, westonruter, jorbin, audrasjb, tobiasbg, swissspidy.

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github-actions · 2025-12-15T03:50:11Z

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t-hamano · 2026-01-04T09:00:53Z

If we simply want to handle multiple feeds, the following approach might work:

diff --git a/src/wp-includes/feed.php b/src/wp-includes/feed.php
index 421bee7173..74f0ee77cd 100644
--- a/src/wp-includes/feed.php
+++ b/src/wp-includes/feed.php
@@ -832,7 +832,20 @@ function fetch_feed( $url ) {
 
        $feed->get_registry()->register( SimplePie\File::class, 'WP_SimplePie_File', true );
 
-       $feed->set_feed_url( $url );
+       if ( is_array( $url ) && count( $url ) > 1 ) {
+               $feed->multifeed_url = array();
+               foreach ( $url as $value ) {
+                       $feed->multifeed_url[] = $feed->get_registry()->call(
+                               SimplePie\Misc::class, 'fix_protocol',
+                               array( $value, 1 )
+                       );
+               }
+       } elseif ( is_array( $url ) && count( $url ) === 1 ) {
+               $feed->set_feed_url( array_shift( $url ) );
+       } else {
+               $feed->set_feed_url( $url );
+       }
+
        /** This filter is documented in wp-includes/class-wp-feed-cache-transien
t.php */
        $feed->set_cache_duration( apply_filters( 'wp_feed_cache_transient_lifeti
me', 12 * HOUR_IN_SECONDS, $url ) );

However, this may not be the recommended approach.

peterwilsoncc · 2026-01-11T23:58:41Z

@t-hamano The hook will still run for each individual URL but it won't run with all of them.

IE fetch_feed( [ 'one.example.com', 'two.example.com' ] ) will fire the hook twice, once for each URL. At the moment it fires once with both URLs as the second parameter.

I'll take a look at your suggested diff. I don't know their plans but I wouldn't be surprised if $feed->multifeed_url[] is removed if/when SimplePie hard deprecate an array of URLs.

t-hamano · 2026-01-12T08:34:14Z

+			$simplepie_instance->set_output_encoding( get_bloginfo( 'charset' ) );
+
+			if ( $simplepie_instance->error() ) {
+				return new WP_Error( 'simplepie-error', $simplepie_instance->error() );


If an error occurs in one feed, the other feeds will be ignored. As I understand it, SimplePie will continue processing even if an error occurs and merge successful feeds:

https://github.com/t-hamano/wordpress-develop/blob/b47e1c7c5985fff02153cd89cbba912aa85b8a02/src/wp-includes/SimplePie/src/SimplePie.php#L1704-L1713

I haven't tested it, but how about an approach like this:

foreach ( (array) $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() ) { $feeds[] = $simplepie_instance; } else { $errors[] = $simplepie_instance->error(); } } if ( empty( $feeds ) ) { return new WP_Error( 'simplepie-error', $errors ); }

We may also need unit tests to ensure that if an error occurs, the rest of the feed still gets processed.

What is the 6.8 behavior for when a feed encounters an error? We should try to replicate that

What is the 6.8 behavior for when a feed encounters an error? We should try to replicate that

An error in any feed triggers WP_Error object. If multiple feeds error then the errors are reported for all the affected feeds.

$ wp eval "var_dump( fetch_feed( [ 'http://example.com/news/feed/', 'https://wordpress.org/news/feed/' ] ) );" phar:///usr/local/src/wp-cli/bin/wp-cli.phar/vendor/wp-cli/eval-command/src/Eval_Command.php(39) : eval()'d code:1: class WP_Error#2462 (3) { public $errors => array(1) { 'simplepie-error' => array(1) { [0] => array(1) { [0] => string(118) "A feed could not be found at `http://example.com/news/feed/`; the status code is `404` and content-type is `text/html`" } } } public $error_data => array(0) { } protected $additional_data => array(0) { } } $ wp eval "var_dump( fetch_feed( [ 'http://example.com/news/feed/', 'https://example.org/news/feed/' ] ) );" phar:///usr/local/src/wp-cli/bin/wp-cli.phar/vendor/wp-cli/eval-command/src/Eval_Command.php(39) : eval()'d code:1: class WP_Error#2462 (3) { public $errors => array(1) { 'simplepie-error' => array(1) { [0] => array(2) { [0] => string(118) "A feed could not be found at `http://example.com/news/feed/`; the status code is `404` and content-type is `text/html`" [1] => string(119) "A feed could not be found at `https://example.org/news/feed/`; the status code is `404` and content-type is `text/html`" } } } public $error_data => array(0) { } protected $additional_data => array(0) { } }

I'll try to replicate that,

t-hamano · 2026-01-12T08:38:45Z

@swissspidy @TobiasBg This is my first time looking at SimplePie code, so I may have missed something, and I'd appreciate any feedback if there is anything.

TobiasBg · 2026-01-12T10:33:12Z

This is my first time looking at SimplePie code

Sorry, I'm not familiar with this specific part either :-(

swissspidy · 2026-01-12T10:45:45Z

Same here

Copilot

Pull request overview

This PR adds support for passing an array of feed URLs to fetch_feed() to handle multiple feeds. When multiple URLs are provided, the function fetches each feed individually, merges their items using SimplePie's merge_items() method, and returns a single SimplePie object with the combined items.

Changes:

Modified fetch_feed() to detect and handle array URLs by fetching each feed individually and merging items
Moved set_feed_url() call to after array processing to avoid setting URL prematurely
Added test coverage to verify multiple feeds are supported without triggering deprecation warnings

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 7 comments.

File	Description
src/wp-includes/feed.php	Implements multi-feed support by cloning SimplePie instance for each URL, fetching items, and merging them via SimplePie::merge_items()
tests/phpunit/tests/feed/fetchFeed.php	Adds test to verify fetch_feed() accepts array of URLs and doesn't trigger SimplePie deprecation warning

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aaronjorbin · 2026-01-14T20:39:28Z

+			$simplepie_instance->set_output_encoding( get_bloginfo( 'charset' ) );
+
+			if ( $simplepie_instance->error() ) {
+				return new WP_Error( 'simplepie-error', $simplepie_instance->error() );


What is the 6.8 behavior for when a feed encounters an error? We should try to replicate that

peterwilsoncc · 2026-01-27T23:07:49Z

@aaronjorbin @t-hamano I've added a bunch of tests for various use cases for both multiple and single feed requests.

On the 6.8 branch there are two different results for unspecified feeds, $url = '' and $url = []:

// 6.8 branch results
There were 2 failures:

1) Tests_Feed_FetchFeed::test_fetch_feed_returns_an_error_for_unspecified_url
A WP_Error object is expected when no URL is provided.
Failed asserting that SimplePie\SimplePie Object (...) is an instance of class "WP_Error".

/vagrant/wordpress-develop/tests/phpunit/includes/abstract-testcase.php:838
/vagrant/wordpress-develop/tests/phpunit/tests/feed/fetchFeed.php:102

2) Tests_Feed_FetchFeed::test_fetch_feed_returns_an_error_for_unspecified_url_array
A WP_Error object is expected when no URL is provided.
Failed asserting that SimplePie\SimplePie Object (...) is an instance of class "WP_Error".

/vagrant/wordpress-develop/tests/phpunit/includes/abstract-testcase.php:838
/vagrant/wordpress-develop/tests/phpunit/tests/feed/fetchFeed.php:115

Changing the first part of the if elseifs to the following results in the same result on both 6.8 and this branch but I think a WP_Error is the best response. What would you prefer?

	if ( empty( $url ) ) {
		$url = ''; // Allow SP to do it's thing with an unspecified URL.
	} elseif ( is_array( $url ) && count( $url ) === 1 ) {

t-hamano

Thanks for the update! This PR looks very stable to me.

On the 6.8 branch there are two different results for unspecified feeds, $url = '' and $url = []:
Changing the first part of the if elseifs to the following results in the same result on both 6.8 and this branch but I think a WP_Error is the best response. What would you prefer?

I agree that the ideal behavior would be to return a WP_Error if $url is a falsy value. However, I think doing so could cause confusion for consumers by unintentionally returning a WP_Error for code that previously didn't cause an error.

For now, I'm leaning towards maintaining the behavior of the 6.8 branch.

peterwilsoncc · 2026-01-28T04:01:32Z

For now, I'm leaning towards maintaining the behavior of the 6.8 branch.

Done in e1c3bcb

t-hamano

LGTM!

Co-Authored-By: westonruter <westonruter@git.wordpress.org>

audrasjb · 2026-01-28T21:31:52Z

+	if ( empty( $url ) ) {
+		// Ensure $url is an empty string, even if passed as an empty array.
+		$url = '';
+	} elseif ( is_array( $url ) && count( $url ) === 1 ) {


Missing yoda here, but not a problem on my side it is ;)

count() is a function call so yoda isn't required as it's impossible to assign a value to it

audrasjb

LGTM as well, just added a small comment. Probably not a blocker.

peterwilsoncc · 2026-01-28T22:01:39Z

I've pushed c50c9f7 to work around the PHP 8.5 deprecation error.

Once simplepie/simplepie#949 is released the commit can be reverted to avoid the duplicate code.

github-actions · 2026-01-28T22:43:13Z

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 61551
GitHub commit: 779509f

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.

peterwilsoncc force-pushed the fix/64136-fetch-feed-deprecation branch from b73e186 to 3ec52a0 Compare December 15, 2025 03:35

peterwilsoncc requested a review from SergeyBiryukov December 15, 2025 22:55

peterwilsoncc force-pushed the fix/64136-fetch-feed-deprecation branch from 3ec52a0 to 1e227d2 Compare December 15, 2025 23:06

t-hamano reviewed Dec 26, 2025

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peterwilsoncc force-pushed the fix/64136-fetch-feed-deprecation branch from 3300255 to c8f11ac Compare January 12, 2026 00:22

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peterwilsoncc force-pushed the fix/64136-fetch-feed-deprecation branch 2 times, most recently from fcc6c73 to a2089a2 Compare January 27, 2026 20:54

peterwilsoncc requested review from aaronjorbin and t-hamano January 27, 2026 23:00

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t-hamano approved these changes Jan 28, 2026

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peterwilsoncc added 4 commits January 29, 2026 08:29

Accept and merge multiple URLs for SimplePie requests.

f2c8f93

Test fetch and merge of multiple feeds.

f9cb80c

Ensure SimplePie is initialized fully.

557799d

De-duplicate initial set up of SimplePie.

4c4785d

peterwilsoncc and others added 13 commits January 29, 2026 08:29

Improve test error message.

e9e71bf

Preserve back-compat for hooks.

c5d2ced

Casting an known array to an array is somewhat pointless.

58033ee

Co-Authored-By: westonruter <westonruter@git.wordpress.org>

Show error message for all erroring URLs.

1a5c909

Account for empty $url parameter.

74df6f3

Clone feed object within loop.

845cc02

Remove single use variable.

d7f15a0

Use different URL for second feed.

02175da

Assert merged feed contains 20 items.

84200e6

Add tests for 404 errors.

3be5869

Tests for no URL provided.

5e92f1f

Chagne error message for no URL, this isn’t WP_HTTP.

e80a037

Retain WP 6.8 behaviour for empty URLs.

fb84424

audrasjb approved these changes Jan 28, 2026

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audrasjb reviewed Jan 28, 2026

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Work around PHP 8.5 deprecation error in SimplePie.

c50c9f7

peterwilsoncc force-pushed the fix/64136-fetch-feed-deprecation branch from 4514883 to c50c9f7 Compare January 28, 2026 21:57

aaronjorbin approved these changes Jan 28, 2026

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github-actions Bot closed this Jan 28, 2026

peterwilsoncc deleted the fix/64136-fetch-feed-deprecation branch January 28, 2026 22:44

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