Adding include method to View library to render view partials within …

…layout-driven views. Fixes #1826

system/View/View.php

@@ -237,7 +237,7 @@ public function render(string $view, array $options = null, $saveData = null): s
 		// When using layouts, the data has already been stored
 		// in $this->sections, and no other valid output
 		// is allowed in $output so we'll overwrite it.
-		if (! is_null($this->layout))
+		if (! is_null($this->layout) && empty($this->currentSection))
 		{
 			$layoutView   = $this->layout;
 			$this->layout = null;
@@ -485,6 +485,22 @@ public function renderSection(string $sectionName)
 
 	//--------------------------------------------------------------------
 
+	/**
+	 * Used within layout views to include additional views.
+	 *
+	 * @param string     $view
+	 * @param array|null $options
+	 * @param null       $saveData
+	 *
+	 * @return string
+	 */
+	public function include(string $view, array $options = null, $saveData = null)
+	{
+		return $this->render($view, $options, $saveData);
+	}
+
+	//--------------------------------------------------------------------
+
 	/**
 	 * Returns the performance data that might have been collected
 	 * during the execution. Used primarily in the Debug Toolbar.

tests/system/View/ViewTest.php

@@ -295,4 +295,18 @@ public function testRenderLayoutSupportsMultipleOfSameSection()
 
 		$this->assertContains($expected, $view->render('extend_two'));
 	}
+
+	public function testRenderLayoutWithInclude()
+	{
+		$view = new View($this->config, $this->viewsDir, $this->loader);
+
+		$view->setVar('testString', 'Hello World');
+		$expected = "<p>Open</p>\n<h1>Hello World</h1>";
+
+		$content = $view->render('extend_include');
+
+		$this->assertTrue(strpos($content, '<p>Open</p>') !== false);
+		$this->assertTrue(strpos($content, '<h1>Hello World</h1>') !== false);
+		$this->assertEquals(2, substr_count($content, 'Hello World'));
+	}
 }

tests/system/View/Views/extend_include.php

@@ -0,0 +1,7 @@
+<?= $this->extend('layout') ?>
+
+<?= $this->section('content') ?>
+
+	<?= $this->include('simple') ?>
+
+<?= $this->endSection() ?>

user_guide_src/source/outgoing/view_layouts.rst

@@ -72,3 +72,23 @@ Rendering the view and it's layout is done exactly as any other view would be di
     }
 
 The renderer is smart enough to detect whether the view should be rendered on its own, or if it needs a layout.
+
+***********************
+Including View Partials
+***********************
+
+View partials are view files that do not extend any layout. They typically include content that can be reused from
+view to view. When using view layouts you must use ``$this->include()`` to include any view partials.
+
+::
+
+    <?= $this->extend('default') ?>
+
+    <?= $this->section('content') ?>
+        <h1>Hello World!</h1>
+
+        <?= $this->include('sidebar') ?>
+    <?= $this->endSection() ?>
+
+When calling the include() method, you can pass it all of the same options that can when rendering a normal view, including
+cache directives, etc.