Fix/tag id mismatch (#112)

* Allow the use of tag slugs in the wp:query block

* Use tag slug instead of id so it survives export

source/wp-content/themes/wporg-news-2021/block-template-parts/front-page/people-of-wordpress.html

@@ -1,4 +1,4 @@
-<!-- wp:query {"query":{"perPage":5,"postType":"post","tagIds":[14]},"tagName":"section","className":"front__people-of-wordpress","align":"full"} -->
+<!-- wp:query {"query":{"perPage":5,"postType":"post","tag":"people-of-wordpress"},"tagName":"section","className":"front__people-of-wordpress","align":"full"} -->
 <section class="front__people-of-wordpress alignfull">
 	<!-- wp:heading {"level":2} -->
 	<h2>People of WordPress</h2>

source/wp-content/themes/wporg-news-2021/functions.php

@@ -324,6 +324,13 @@ function custom_query_block_attributes( $parsed_block ) {
 				$parsed_block[ 'attrs' ][ 'query' ][ 'categoryIds' ] = [ $category->term_id ];
 			}
 		}
+		if ( isset( $parsed_block[ 'attrs' ][ 'query' ][ 'tag' ] ) ) {
+			$tag = get_term_by( 'slug', $parsed_block[ 'attrs' ][ 'query' ][ 'tag' ], 'post_tag' );
+			if ( $tag ) {
+				$parsed_block[ 'attrs' ][ 'query' ][ 'tagIds' ] = [ $tag->term_id ];
+			}
+
+		}
 	}
 
 	return $parsed_block;