Use field-specific sanitization in WP_Tax_Query::transform_query().

When terms are entered into the database, term fields are sanitized with
`sanitize_term_field()`. To ensure that the `SELECT ... WHERE` queries in
`WP_Tax_Query::transform_query()` are not broken by overzealous sanitization,
`sanitize_term_field()` should be used in that case as well. This fixes a bug
where a tax_query using 'field=name' would fail if the 'terms' parameter
contained characters (like spaces) that were improperly removed by
`sanitize_title_for_query()`.

Fixes #27810.

git-svn-id: https://develop.svn.wordpress.org/trunk@31346 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/query/taxQuery.php

@@ -59,6 +59,36 @@ class Tests_Query_TaxQuery extends WP_UnitTestCase {
 		$this->assertEquals( array( $p1 ), $q->posts );
 	}
 
+	/**
+	 * @ticket 27810
+	 */
+	public function test_field_name_should_work_for_names_with_spaces() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$t = $this->factory->term->create( array(
+			'taxonomy' => 'wptests_tax',
+			'slug' => 'foo',
+			'name' => 'Foo Bar',
+		) );
+		$p1 = $this->factory->post->create();
+		$p2 = $this->factory->post->create();
+
+		wp_set_object_terms( $p1, $t, 'wptests_tax' );
+
+		$q = new WP_Query( array(
+			'fields' => 'ids',
+			'tax_query' => array(
+				array(
+					'taxonomy' => 'wptests_tax',
+					'terms' => array( 'Foo Bar' ),
+					'field' => 'name',
+				),
+			),
+		) );
+
+		$this->assertEquals( array( $p1 ), $q->posts );
+	}
+
 	public function test_tax_query_single_query_single_term_field_term_taxonomy_id() {
 		$t = $this->factory->term->create( array(
 			'taxonomy' => 'category',