From a37ee6171e1ba969307128cc901fa6cddd461b41 Mon Sep 17 00:00:00 2001
From: Gary Pendergast <pento@git.wordpress.org>
Date: Tue, 8 Jan 2019 03:46:58 +0000
Subject: [PATCH] Permalinks: Add a `pre_wp_unique_post_slug` filter.

Returning a non-`null` value on this fillter will cause `wp_unique_post_slug()` to return early with that value, skipping potentially expensive database queries on some sites.

Props coffee2code, javorszky, iCaleb.
Fixes #21112.



git-svn-id: https://develop.svn.wordpress.org/trunk@44454 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/post.php     | 20 ++++++++++++++++++++
 tests/phpunit/tests/post.php | 26 ++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index 8debd3db3b..f3696341da 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -4117,6 +4117,26 @@ function wp_unique_post_slug( $slug, $post_ID, $post_status, $post_type, $post_p
 		return $slug;
 	}
 
+	/**
+	 * Filters the post slug before it is generated to be unique.
+	 *
+	 * Returning a non-null value will short-circuit the
+	 * unique slug generation, returning the passed value instead.
+	 *
+	 * @since 5.1.0
+	 *
+	 * @param string $override_slug Short-circuit return value.
+	 * @param string $slug          The desired slug (post_name).
+	 * @param int    $post_ID       Post ID.
+	 * @param string $post_status   The post status.
+	 * @param string $post_type     Post type.
+	 * @param int    $post_parent   Post parent ID.
+	 */
+	$override_slug = apply_filters( 'pre_wp_unique_post_slug', null, $slug, $post_ID, $post_status, $post_type, $post_parent );
+	if ( null !== $override_slug ) {
+		return $override_slug;
+	}
+
 	global $wpdb, $wp_rewrite;
 
 	$original_slug = $slug;
diff --git a/tests/phpunit/tests/post.php b/tests/phpunit/tests/post.php
index 3239170a09..d0d902978c 100644
--- a/tests/phpunit/tests/post.php
+++ b/tests/phpunit/tests/post.php
@@ -1357,4 +1357,30 @@ class Tests_Post extends WP_UnitTestCase {
 		$this->assertEquals( $changeset_data, json_decode( get_post( $post_id )->post_content, true ) );
 	}
 
+	/**
+	 * Test ensuring that the post_slug can be filtered with a custom value short circuiting the built in
+	 * function that tries to create a unique name based on the post name.
+	 *
+	 * @see wp_unique_post_slug()
+	 * @ticket 21112
+	 */
+	function test_pre_wp_unique_post_slug_filter() {
+		add_filter( 'pre_wp_unique_post_slug', array( $this, 'filter_pre_wp_unique_post_slug' ), 10, 6 );
+
+		$post_id = $this->factory->post->create(
+			array(
+				'title'       => 'An example',
+				'post_status' => 'publish',
+				'post_type'   => 'page',
+			)
+		);
+		$post    = get_post( $post_id );
+		$this->assertEquals( 'override-slug-' . $post->post_type, $post->post_name );
+
+		remove_filter( 'pre_wp_unique_post_slug', array( $this, 'filter_pre_wp_unique_post_slug' ), 10, 6 );
+	}
+
+	function filter_pre_wp_unique_post_slug( $default, $slug, $post_ID, $post_status, $post_type, $post_parent ) {
+		return 'override-slug-' . $post_type;
+	}
 }