Changeset 61066

Timestamp:

10/26/2025 09:19:07 PM (6 weeks ago)

Author:

ramonopoly

Message:

get_adjacent_post: modify WHERE clause to include ID-based fallback to ensure deterministic ordering

Since WordPress 2.7, where multiple posts have identical post_date values (e.g., when bulk publishing drafts), the next/previous post navigation skips posts or behaves unpredictably. This is because the WHERE clause uses strict inequality (> or <) which excludes posts with the same date.

To ensure deterministic ordering, this commit modifies the WHERE clause to include ID-based fallback for posts with identical dates.

Props ramonopoly, westonruter, andrewserong.

Fixes #8107.

Location:

trunk

Files:

• src/wp-includes/link-template.php (modified) (6 diffs)
• tests/phpunit/tests/link/getAdjacentPost.php (modified) (1 diff)
• tests/phpunit/tests/url.php (modified) (1 diff)

trunk/src/wp-includes/link-template.php

@@ -1940 +1940 @@
     }
 
-    $op    = $previous ? '<' : '>';
-    $order = $previous ? 'DESC' : 'ASC';
+    $comparison_operator = $previous ? '<' : '>';
+    $order               = $previous ? 'DESC' : 'ASC';
 
     /**
@@ -1965 +1965 @@
     $join = apply_filters( "get_{$adjacent}_post_join", $join, $in_same_term, $excluded_terms, $taxonomy, $post );
 
+    // Prepare the where clause for the adjacent post query.
+    $where_prepared = $wpdb->prepare( "WHERE (p.post_date $comparison_operator %s OR (p.post_date = %s AND p.ID $comparison_operator %d)) AND p.post_type = %s $where", $current_post_date, $current_post_date, $post->ID, $post->post_type ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- $comparison_operator is a string literal, either '<' or '>'.
+
     /**
      * Filters the WHERE clause in the SQL for an adjacent post query.
@@ -1978 +1981 @@
      * @since 2.5.0
      * @since 4.4.0 Added the `$taxonomy` and `$post` parameters.
+     * @since 6.9.0 Adds ID-based fallback for posts with identical dates in adjacent post queries.
      *
      * @param string       $where          The `WHERE` clause in the SQL.
@@ -1985 +1989 @@
      * @param WP_Post      $post           WP_Post object.
      */
-    $where = apply_filters( "get_{$adjacent}_post_where", $wpdb->prepare( "WHERE p.post_date $op %s AND p.post_type = %s $where", $current_post_date, $post->post_type ), $in_same_term, $excluded_terms, $taxonomy, $post );
+    $where = apply_filters( "get_{$adjacent}_post_where", $where_prepared, $in_same_term, $excluded_terms, $taxonomy, $post );
 
     /**
@@ -2001 +2005 @@
      * @since 4.4.0 Added the `$post` parameter.
      * @since 4.9.0 Added the `$order` parameter.
+     * @since 6.9.0 Adds ID sort to ensure deterministic ordering for posts with identical dates.
      *
      * @param string $order_by The `ORDER BY` clause in the SQL.
@@ -2006 +2011 @@
      * @param string  $order   Sort order. 'DESC' for previous post, 'ASC' for next.
      */
-    $sort = apply_filters( "get_{$adjacent}_post_sort", "ORDER BY p.post_date $order LIMIT 1", $post, $order );
+    $sort = apply_filters( "get_{$adjacent}_post_sort", "ORDER BY p.post_date $order, p.ID $order LIMIT 1", $post, $order );
 
     $query        = "SELECT p.ID FROM $wpdb->posts AS p $join $where $sort";

trunk/tests/phpunit/tests/link/getAdjacentPost.php

@@ -588 +588 @@
         $this->assertSame( get_num_queries() - $num_queries, 2, 'Number of queries run was not two after adding new term' );
     }
+
+    /**
+     * Test get_adjacent_post with posts having identical post_date.
+     *
+     * @ticket 8107
+     */
+    public function test_get_adjacent_post_with_identical_dates() {
+        $identical_date = '2024-01-01 12:00:00';
+
+        // Create posts with identical dates but different IDs.
+        $post_ids = array();
+        for ( $i = 1; $i <= 5; $i++ ) {
+            $post_ids[] = self::factory()->post->create(
+                array(
+                    'post_title' => "Post $i",
+                    'post_date'  => $identical_date,
+                )
+            );
+        }
+
+        // Test navigation from the middle post (ID: 3rd post).
+        $current_post_id = $post_ids[2]; // 3rd post
+        $this->go_to( get_permalink( $current_post_id ) );
+
+        // Previous post should be the 2nd post (lower ID, same date).
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertInstanceOf( 'WP_Post', $previous );
+        $this->assertEquals( $post_ids[1], $previous->ID );
+
+        // Next post should be the 4th post (higher ID, same date).
+        $next = get_adjacent_post( false, '', false );
+        $this->assertInstanceOf( 'WP_Post', $next );
+        $this->assertEquals( $post_ids[3], $next->ID );
+    }
+
+    /**
+     * Test get_adjacent_post with mixed dates and identical dates.
+     *
+     * @ticket 8107
+     */
+    public function test_get_adjacent_post_mixed_dates_with_identical_groups() {
+        // Create posts with different dates.
+        $post_early = self::factory()->post->create(
+            array(
+                'post_title' => 'Early Post',
+                'post_date'  => '2024-01-01 10:00:00',
+            )
+        );
+
+        // Create multiple posts with identical date.
+        $identical_date = '2024-01-01 12:00:00';
+        $post_ids       = array();
+        for ( $i = 1; $i <= 3; $i++ ) {
+            $post_ids[] = self::factory()->post->create(
+                array(
+                    'post_title' => "Identical Post $i",
+                    'post_date'  => $identical_date,
+                )
+            );
+        }
+
+        $post_late = self::factory()->post->create(
+            array(
+                'post_title' => 'Late Post',
+                'post_date'  => '2024-01-01 14:00:00',
+            )
+        );
+
+        // Test from first identical post.
+        $this->go_to( get_permalink( $post_ids[0] ) );
+
+        // Previous should be the early post (different date).
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertInstanceOf( 'WP_Post', $previous );
+        $this->assertEquals( $post_early, $previous->ID );
+
+        // Next should be the second identical post (same date, higher ID).
+        $next = get_adjacent_post( false, '', false );
+        $this->assertInstanceOf( 'WP_Post', $next );
+        $this->assertEquals( $post_ids[1], $next->ID );
+
+        // Test from middle identical post.
+        $this->go_to( get_permalink( $post_ids[1] ) );
+
+        // Previous should be the first identical post (same date, lower ID).
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertInstanceOf( 'WP_Post', $previous );
+        $this->assertEquals( $post_ids[0], $previous->ID );
+
+        // Next should be the third identical post (same date, higher ID).
+        $next = get_adjacent_post( false, '', false );
+        $this->assertInstanceOf( 'WP_Post', $next );
+        $this->assertEquals( $post_ids[2], $next->ID );
+
+        // Test from last identical post.
+        $this->go_to( get_permalink( $post_ids[2] ) );
+
+        // Previous should be the second identical post (same date, lower ID).
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertInstanceOf( 'WP_Post', $previous );
+        $this->assertEquals( $post_ids[1], $previous->ID );
+
+        // Next should be the late post (different date).
+        $next = get_adjacent_post( false, '', false );
+        $this->assertInstanceOf( 'WP_Post', $next );
+        $this->assertEquals( $post_late, $next->ID );
+    }
+
+    /**
+     * Test get_adjacent_post navigation through all posts with identical dates.
+     *
+     * @ticket 8107
+     */
+    public function test_get_adjacent_post_navigation_through_identical_dates() {
+        $identical_date = '2024-01-01 12:00:00';
+
+        // Create 4 posts with identical dates.
+        $post_ids = array();
+        for ( $i = 1; $i <= 4; $i++ ) {
+            $post_ids[] = self::factory()->post->create(
+                array(
+                    'post_title' => "Post $i",
+                    'post_date'  => $identical_date,
+                )
+            );
+        }
+
+        // Test navigation sequence: 1 -> 2 -> 3 -> 4.
+        $this->go_to( get_permalink( $post_ids[0] ) );
+
+        // From post 1, next should be post 2.
+        $next = get_adjacent_post( false, '', false );
+        $this->assertEquals( $post_ids[1], $next->ID );
+
+        // From post 2, previous should be post 1, next should be post 3.
+        $this->go_to( get_permalink( $post_ids[1] ) );
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertEquals( $post_ids[0], $previous->ID );
+        $next = get_adjacent_post( false, '', false );
+        $this->assertEquals( $post_ids[2], $next->ID );
+
+        // From post 3, previous should be post 2, next should be post 4.
+        $this->go_to( get_permalink( $post_ids[2] ) );
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertEquals( $post_ids[1], $previous->ID );
+        $next = get_adjacent_post( false, '', false );
+        $this->assertEquals( $post_ids[3], $next->ID );
+
+        // From post 4, previous should be post 3.
+        $this->go_to( get_permalink( $post_ids[3] ) );
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertEquals( $post_ids[2], $previous->ID );
+    }
+
+    /**
+     * Test get_adjacent_post with identical dates and category filtering.
+     *
+     * @ticket 8107
+     */
+    public function test_get_adjacent_post_identical_dates_with_category() {
+        $identical_date = '2024-01-01 12:00:00';
+        $category_id    = self::factory()->category->create( array( 'name' => 'Test Category' ) );
+
+        // Create posts with identical dates, some in category.
+        $post_ids = array();
+        for ( $i = 1; $i <= 4; $i++ ) {
+            $post_id = self::factory()->post->create(
+                array(
+                    'post_title' => "Post $i",
+                    'post_date'  => $identical_date,
+                )
+            );
+
+            // Add every other post to the category.
+            if ( 0 === $i % 2 ) {
+                wp_set_post_categories( $post_id, array( $category_id ) );
+            }
+
+            $post_ids[] = $post_id;
+        }
+
+        // Test from post 2 (in category).
+        $this->go_to( get_permalink( $post_ids[1] ) );
+
+        // With category filtering, should only see posts in same category.
+        $previous = get_adjacent_post( true, '', true, 'category' );
+        $this->assertSame( '', $previous ); // No previous post in category
+
+        $next = get_adjacent_post( true, '', false, 'category' );
+        $this->assertInstanceOf( 'WP_Post', $next );
+        $this->assertEquals( $post_ids[3], $next->ID ); // Post 4 (in category)
+    }
 }

trunk/tests/phpunit/tests/url.php

@@ -570 +570 @@
         }
     }
+
+    /**
+     * Test get_adjacent_post with posts having identical post_date.
+     *
+     * @ticket 8107
+     * @covers ::get_adjacent_post
+     */
+    public function test_get_adjacent_post_with_identical_dates() {
+        $identical_date = gmdate( 'Y-m-d H:i:s', time() );
+
+        // Create 3 posts with identical dates but different IDs.
+        $post_ids = array();
+        for ( $i = 1; $i <= 3; $i++ ) {
+            $post_ids[] = self::factory()->post->create(
+                array(
+                    'post_title' => "Identical Post $i",
+                    'post_date'  => $identical_date,
+                )
+            );
+        }
+
+        // Test from the middle post (2nd post).
+        $GLOBALS['post'] = get_post( $post_ids[1] );
+
+        // Previous post should be the 1st post (lower ID, same date).
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertInstanceOf( 'WP_Post', $previous );
+        $this->assertSame( $post_ids[0], $previous->ID );
+
+        // Next post should be the 3rd post (higher ID, same date).
+        $next = get_adjacent_post( false, '', false );
+        $this->assertInstanceOf( 'WP_Post', $next );
+        $this->assertSame( $post_ids[2], $next->ID );
+
+        // Test from the first post.
+        $GLOBALS['post'] = get_post( $post_ids[0] );
+
+        // Previous should be empty (no earlier posts).
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertSame( '', $previous );
+
+        // Next should be the 2nd post.
+        $next = get_adjacent_post( false, '', false );
+        $this->assertInstanceOf( 'WP_Post', $next );
+        $this->assertSame( $post_ids[1], $next->ID );
+
+        // Test from the last post.
+        $GLOBALS['post'] = get_post( $post_ids[2] );
+
+        // Previous should be the 2nd post.
+        $previous = get_adjacent_post( false, '', true );
+        $this->assertInstanceOf( 'WP_Post', $previous );
+        $this->assertSame( $post_ids[1], $previous->ID );
+
+        // Next should be empty (no later posts).
+        $next = get_adjacent_post( false, '', false );
+        $this->assertSame( '', $next );
+    }
 }