Maintain backwards compatible behaviour post_content (#8077)

When transforming classic content to a shortcode block, or having a post with a single freeform block in it, `post_content` ended up in a state that wasn't backward compatible.

This change ensures that un-blockified posts can continue to be used in the Classic Editor as expected, and that the shortcode block both renders in Gutenberg correctly, and on the front end.

Fixes #3900.

core-blocks/shortcode/index.js

@@ -1,6 +1,7 @@
 /**
  * WordPress dependencies
  */
+import { removep, autop } from '@wordpress/autop';
 import { RawHTML } from '@wordpress/element';
 import { __ } from '@wordpress/i18n';
 import { Dashicon } from '@wordpress/components';
@@ -46,7 +47,7 @@ export const settings = {
 					text: {
 						type: 'string',
 						shortcode: ( attrs, { content } ) => {
-							return content;
+							return removep( autop( content ) );
 						},
 					},
 				},

core-blocks/shortcode/index.php

@@ -0,0 +1,29 @@
+<?php
+/**
+ * Server-side rendering of the `core/shortcode` block.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Performs wpautop() on the shortcode block content.
+ *
+ * @param array  $attributes The block attributes.
+ * @param string $content    The block content.
+ *
+ * @return string Returns the block content.
+ */
+function render_block_core_shortcode( $attributes, $content ) {
+	return wpautop( $content );
+}
+
+/**
+ * Registers the `core/shortcode` block on server.
+ */
+function register_block_core_shortcode() {
+	register_block_type( 'core/shortcode', array(
+		'render_callback' => 'render_block_core_shortcode',
+	) );
+}
+
+add_action( 'init', 'register_block_core_shortcode' );

docs/blocks/creating-dynamic-blocks.md

@@ -89,7 +89,7 @@ Because it is a dynamic block it also needs a server component. The rendering ca
 <?php
 // block.php
 
-function my_plugin_render_block_latest_post( $attributes ) {
+function my_plugin_render_block_latest_post( $attributes, $content ) {
 	$recent_posts = wp_get_recent_posts( array(
 		'numberposts' => 1,
 		'post_status' => 'publish',
@@ -115,7 +115,7 @@ There are a few things to notice:
 
 * The edit function still shows a representation of the block in the editor's context (this could be very different from the rendered version, it's up to the block's author)
 * The save function just returns null because the rendering is performed server-side.
-* The server-side rendering is a function taking the block attributes as an argument and returning the markup (quite similar to shortcodes)
+* The server-side rendering is a function taking the block attributes and the block inner content as arguments, and returning the markup (quite similar to shortcodes)
 
 ## Live rendering in Gutenberg editor
 

editor/store/selectors.js

@@ -22,10 +22,11 @@ import createSelector from 'rememo';
 /**
  * WordPress dependencies
  */
-import { serialize, getBlockType, getBlockTypes, hasBlockSupport, hasChildBlocks } from '@wordpress/blocks';
+import { serialize, getBlockType, getBlockTypes, hasBlockSupport, hasChildBlocks, getUnknownTypeHandlerName } from '@wordpress/blocks';
 import { __ } from '@wordpress/i18n';
 import { moment } from '@wordpress/date';
 import deprecated from '@wordpress/deprecated';
+import { removep } from '@wordpress/autop';
 
 /***
  * Module constants
@@ -1352,7 +1353,13 @@ export const getEditedPostContent = createSelector(
 			return edits.content;
 		}
 
-		return serialize( getBlocks( state ) );
+		const blocks = getBlocks( state );
+
+		if ( blocks.length === 1 && blocks[ 0 ].name === getUnknownTypeHandlerName() ) {
+			return removep( serialize( blocks ) );
+		}
+
+		return serialize( blocks );
 	},
 	( state ) => [
 		state.editor.present.edits.content,

lib/blocks.php

@@ -177,8 +177,7 @@ function do_blocks( $content ) {
 			}
 		}
 
-		// Replace dynamic block with server-rendered output.
-		$rendered_content .= $block_type->render( $attributes );
+		$inner_content = '';
 
 		if ( ! $is_self_closing ) {
 			$end_tag_pattern = '/<!--\s+\/wp:' . str_replace( '/', '\/', preg_quote( $block_name ) ) . '\s+-->/';
@@ -192,8 +191,12 @@ function do_blocks( $content ) {
 			$end_tag    = $block_match_end[0][0];
 			$end_offset = $block_match_end[0][1];
 
-			$content = substr( $content, $end_offset + strlen( $end_tag ) );
+			$inner_content = substr( $content, 0, $end_offset );
+			$content       = substr( $content, $end_offset + strlen( $end_tag ) );
 		}
+
+		// Replace dynamic block with server-rendered output.
+		$rendered_content .= $block_type->render( $attributes, $inner_content );
 	}
 
 	// Append remaining unmatched content.

lib/class-wp-block-type.php

@@ -94,17 +94,18 @@ public function __construct( $block_type, $args = array() ) {
 	 *
 	 * @since 0.6.0
 	 *
-	 * @param array $attributes Optional. Block attributes. Default empty array.
+	 * @param array  $attributes Optional. Block attributes. Default empty array.
+	 * @param string $content    Optional. Block content. Default empty string.
 	 * @return string Rendered block type output.
 	 */
-	public function render( $attributes = array() ) {
+	public function render( $attributes = array(), $content = '' ) {
 		if ( ! $this->is_dynamic() ) {
 			return '';
 		}
 
 		$attributes = $this->prepare_attributes_for_render( $attributes );
 
-		return (string) call_user_func( $this->render_callback, $attributes );
+		return (string) call_user_func( $this->render_callback, $attributes, $content );
 	}
 
 	/**

phpunit/class-block-type-test.php

@@ -36,6 +36,23 @@ function test_render() {
 		$this->assertEquals( $attributes, json_decode( $output, true ) );
 	}
 
+	function test_render_with_content() {
+		$attributes = array(
+			'foo' => 'bar',
+			'bar' => 'foo',
+		);
+
+		$content = 'baz';
+
+		$expected = array_merge( $attributes, array( '_content' => $content ) );
+
+		$block_type = new WP_Block_Type( 'core/dummy', array(
+			'render_callback' => array( $this, 'render_dummy_block_with_content' ),
+		) );
+		$output     = $block_type->render( $attributes, $content );
+		$this->assertEquals( $expected, json_decode( $output, true ) );
+	}
+
 	function test_render_for_static_block() {
 		$block_type = new WP_Block_Type( 'core/dummy', array() );
 		$output     = $block_type->render();

phpunit/class-do-blocks-test.php

@@ -22,4 +22,26 @@ function test_do_blocks_removes_comments() {
 
 		$this->assertEquals( $expected_html, $actual_html );
 	}
+
+	/**
+	 * Test that shortcode blocks get the same HTML as shortcodes in Classic content.
+	 */
+	function test_the_content() {
+		add_shortcode( 'someshortcode', array( $this, 'handle_shortcode' ) );
+
+		$classic_content = "Foo\n\n[someshortcode]\n\nBar\n\n[/someshortcode]\n\nBaz";
+		$block_content   = "<!-- wp:core/paragraph -->\n<p>Foo</p>\n<!-- /wp:core/paragraph -->\n\n<!-- wp:core/shortcode -->[someshortcode]\n\nBar\n\n[/someshortcode]<!-- /wp:core/shortcode -->\n\n<!-- wp:core/paragraph -->\n<p>Baz</p>\n<!-- /wp:core/paragraph -->";
+
+		$classic_filtered_content = apply_filters( 'the_content', $classic_content );
+		$block_filtered_content   = apply_filters( 'the_content', $block_content );
+
+		// Block rendering add some extra blank lines, but we're not worried about them.
+		$block_filtered_content = preg_replace( "/\n{2,}/", "\n", $block_filtered_content );
+
+		$this->assertEquals( $classic_filtered_content, $block_filtered_content );
+	}
+
+	function handle_shortcode( $atts, $content ) {
+		return $content;
+	}
 }

phpunit/fixtures/do-blocks-expected.html

@@ -10,3 +10,8 @@
 <p>Third Gutenberg Paragraph</p>
 
 <p>Third Auto Paragraph</p>
+
+<p>[someshortcode]</p>
+<p>And some content?!</p>
+<p>[/someshortcode]</p>
+

phpunit/fixtures/do-blocks-original.html

@@ -15,3 +15,11 @@
 <!-- /wp:core/paragraph -->
 
 <p>Third Auto Paragraph</p>
+
+<!-- wp:core/shortcode -->
+[someshortcode]
+
+And some content?!
+
+[/someshortcode]
+<!-- /wp:core/shortcode -->