From 5bcee9e93931fae6fd3584a33746d44a8125c4cd Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Sun, 25 Jan 2015 02:45:11 +0000
Subject: [PATCH] In `get_terms()`, check hierarchy for all `$taxonomies`
 before bailing early from 'parent' or 'child_of'.

There is a pre-check in `get_terms()` that prevents an unnecessary database
query if the 'parent' or 'child_of' parameter is not found in the cached term
hierarchy (since a term without an index in the hierarchy cache has no
descendants). Previously, only the first item in the `$taxonomies` array was
being checked, with the result that an empty array was being erroneously
returned in cases where the 'parent' or 'child_of' term is in a subsequent
taxonomy.

See #31118.

git-svn-id: https://develop.svn.wordpress.org/trunk@31276 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/taxonomy.php          | 35 ++++++++----
 tests/phpunit/tests/term/getTerms.php | 82 +++++++++++++++++++++++++++
 2 files changed, 106 insertions(+), 11 deletions(-)

diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index 9535b4e902..e5816580d1 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -1657,18 +1657,29 @@ function get_terms( $taxonomies, $args = '' ) {
 	 */
 	$args = apply_filters( 'get_terms_args', $args, $taxonomies );
 
+	// Avoid the query if the queried parent/child_of term has no descendants.
 	$child_of = $args['child_of'];
+	$parent   = $args['parent'];
+
 	if ( $child_of ) {
-		$hierarchy = _get_term_hierarchy( reset( $taxonomies ) );
-		if ( ! isset( $hierarchy[ $child_of ] ) ) {
-			return $empty_array;
-		}
+		$_parent = $child_of;
+	} elseif ( $parent ) {
+		$_parent = $parent;
+	} else {
+		$_parent = false;
 	}
 
-	$parent = $args['parent'];
-	if ( $parent ) {
-		$hierarchy = _get_term_hierarchy( reset( $taxonomies ) );
-		if ( ! isset( $hierarchy[ $parent ] ) ) {
+	if ( $_parent ) {
+		$in_hierarchy = false;
+		foreach ( $taxonomies as $_tax ) {
+			$hierarchy = _get_term_hierarchy( $_tax );
+
+			if ( isset( $hierarchy[ $_parent ] ) ) {
+				$in_hierarchy = true;
+			}
+		}
+
+		if ( ! $in_hierarchy ) {
 			return $empty_array;
 		}
 	}
@@ -1942,9 +1953,11 @@ function get_terms( $taxonomies, $args = '' ) {
 	}
 
 	if ( $child_of ) {
-		$children = _get_term_hierarchy( reset( $taxonomies ) );
-		if ( ! empty( $children ) ) {
-			$terms = _get_term_children( $child_of, $terms, reset( $taxonomies ) );
+		foreach ( $taxonomies as $_tax ) {
+			$children = _get_term_hierarchy( $_tax );
+			if ( ! empty( $children ) ) {
+				$terms = _get_term_children( $child_of, $terms, $_tax );
+			}
 		}
 	}
 
diff --git a/tests/phpunit/tests/term/getTerms.php b/tests/phpunit/tests/term/getTerms.php
index b8ea31e9b2..625d0657a0 100644
--- a/tests/phpunit/tests/term/getTerms.php
+++ b/tests/phpunit/tests/term/getTerms.php
@@ -376,6 +376,47 @@ class Tests_Term_getTerms extends WP_UnitTestCase {
 		$this->assertEquals( 1, count( $terms ) );
 	}
 
+	/**
+	 * @ticket 31118
+	 */
+	public function test_child_of_should_skip_query_when_specified_parent_is_not_found_in_hierarchy_cache() {
+		global $wpdb;
+
+		register_taxonomy( 'wptests_tax', 'post', array( 'hierarchical' => true, ) );
+
+		$terms = $this->factory->term->create_many( 3, array( 'taxonomy' => 'wptests_tax' ) );
+
+		$num_queries = $wpdb->num_queries;
+
+		$found = get_terms( 'wptests_tax', array(
+			'hide_empty' => false,
+			'child_of' => $terms[0],
+		) );
+
+		$this->assertEmpty( $found );
+		$this->assertSame( $num_queries, $wpdb->num_queries );
+	}
+
+	/**
+	 * @ticket 31118
+	 */
+	public function test_child_of_should_respect_multiple_taxonomies() {
+		register_taxonomy( 'wptests_tax1', 'post', array( 'hierarchical' => true ) );
+		register_taxonomy( 'wptests_tax2', 'post', array( 'hierarchical' => true ) );
+
+		$t1 = $this->factory->term->create( array( 'taxonomy' => 'wptests_tax1' ) );
+		$t2 = $this->factory->term->create( array( 'taxonomy' => 'wptests_tax2' ) );
+		$t3 = $this->factory->term->create( array( 'taxonomy' => 'wptests_tax2', 'parent' => $t2 ) );
+
+		$found = get_terms( array( 'wptests_tax1', 'wptests_tax2' ), array(
+			'fields' => 'ids',
+			'hide_empty' => false,
+			'child_of' => $t2,
+		) );
+
+		$this->assertEqualSets( array( $t3 ), $found );
+	}
+
 	/**
 	 * @ticket 27123
 	 */
@@ -1156,6 +1197,47 @@ class Tests_Term_getTerms extends WP_UnitTestCase {
 		$this->assertEqualSets( $expected, $actual );
 	}
 
+	/**
+	 * @ticket 31118
+	 */
+	public function test_parent_should_skip_query_when_specified_parent_is_not_found_in_hierarchy_cache() {
+		global $wpdb;
+
+		register_taxonomy( 'wptests_tax', 'post', array( 'hierarchical' => true, ) );
+
+		$terms = $this->factory->term->create_many( 3, array( 'taxonomy' => 'wptests_tax' ) );
+
+		$num_queries = $wpdb->num_queries;
+
+		$found = get_terms( 'wptests_tax', array(
+			'hide_empty' => false,
+			'parent' => $terms[0],
+		) );
+
+		$this->assertEmpty( $found );
+		$this->assertSame( $num_queries, $wpdb->num_queries );
+	}
+
+	/**
+	 * @ticket 31118
+	 */
+	public function test_parent_should_respect_multiple_taxonomies() {
+		register_taxonomy( 'wptests_tax1', 'post', array( 'hierarchical' => true ) );
+		register_taxonomy( 'wptests_tax2', 'post', array( 'hierarchical' => true ) );
+
+		$t1 = $this->factory->term->create( array( 'taxonomy' => 'wptests_tax1' ) );
+		$t2 = $this->factory->term->create( array( 'taxonomy' => 'wptests_tax2' ) );
+		$t3 = $this->factory->term->create( array( 'taxonomy' => 'wptests_tax2', 'parent' => $t2 ) );
+
+		$found = get_terms( array( 'wptests_tax1', 'wptests_tax2' ), array(
+			'fields' => 'ids',
+			'hide_empty' => false,
+			'parent' => $t2,
+		) );
+
+		$this->assertEqualSets( array( $t3 ), $found );
+	}
+
 	public function test_hierarchical_false_parent_should_override_child_of() {
 		$initial_terms = $this->create_hierarchical_terms();