Add sample single page to manage config value

Fixed #4

controller.php

@@ -35,7 +35,7 @@ class Controller extends Package
      *
      * @var string
      */
-    protected $pkgVersion = '0.0.4';
+    protected $pkgVersion = '0.0.5';
 
     /**
      * @see https://documentation.concretecms.org/developers/packages/adding-custom-code-to-packages

controllers/single_page/dashboard/system/boilerplate.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Concrete\Package\V9PackageBoilerplate\Controller\SinglePage\Dashboard\System;
+
+use Concrete\Core\Page\Controller\DashboardPageController;
+use Concrete\Core\Url\Resolver\Manager\ResolverManagerInterface;
+
+class Boilerplate extends DashboardPageController
+{
+    public function view()
+    {
+        /** @var ResolverManagerInterface $resolver */
+        $resolver = $this->app->make(ResolverManagerInterface::class);
+
+        return $this->buildRedirect($resolver->resolve(['/dashboard/system/boilerplate/config']));
+    }
+}

controllers/single_page/dashboard/system/boilerplate/config.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Concrete\Package\V9PackageBoilerplate\Controller\SinglePage\Dashboard\System\Boilerplate;
+
+use Concrete\Core\Config\Repository\Liaison;
+use Concrete\Core\Package\PackageService;
+use Concrete\Core\Page\Controller\DashboardPageController;
+use Symfony\Component\HttpFoundation\RedirectResponse;
+
+class Config extends DashboardPageController
+{
+    public function view()
+    {
+        $config = $this->getConfig();
+        if ($config) {
+            $example_value = $config->get('app.example');
+            $this->set('example_value', $example_value);
+        }
+    }
+
+    public function submit(): ?RedirectResponse
+    {
+        if (!$this->token->validate('update_config')) {
+            $this->error->add($this->token->getErrorMessage());
+        }
+
+        $example_value = trim($this->post('example_key'));
+        if (empty($example_value)) {
+            $this->error->add(t('The key is required.'));
+        }
+
+        if (!$this->error->has()) {
+            $config = $this->getConfig();
+            if ($config) {
+                $config->save('app.example', $example_value);
+                $this->flash('success', t('The settings has been successfully updated.'));
+            }
+
+            return $this->buildRedirect([$this->getPageObject()]);
+        }
+
+        return null;
+    }
+
+    protected function getConfig(): ?Liaison
+    {
+        /** @var PackageService $packageService */
+        $packageService = $this->app->make(PackageService::class);
+        $package = $packageService->getClass('v9_package_boilerplate');
+        if ($package) {
+            return $package->getFileConfig();
+        }
+
+        return null;
+    }
+}

install/singlepages.xml

@@ -25,5 +25,17 @@
                 </attributekey>
             </attributes>
         </page>
+        <page name="Boilerplate"
+              path="/dashboard/system/boilerplate"
+              filename="/dashboard/system/boilerplate/view.php"
+              pagetype=""
+              description=""
+              package="v9_package_boilerplate"/>
+        <page name="Config"
+              path="/dashboard/system/boilerplate/config"
+              filename="/dashboard/system/boilerplate/config.php"
+              pagetype=""
+              description=""
+              package="v9_package_boilerplate"/>
     </singlepages>
 </concrete5-cif>

single_pages/dashboard/system/boilerplate/config.php

@@ -0,0 +1,26 @@
+<?php
+defined('C5_EXECUTE') or die('Access Denied.');
+
+/** @var \Concrete\Core\Page\View\PageView $view */
+/** @var \Concrete\Core\Form\Service\Form $form */
+/** @var \Concrete\Core\Validation\CSRF\Token $token */
+
+$example_value = $example_value ?? null;
+?>
+<form action="<?= $view->action('submit') ?>" method="post">
+    <?php $token->output('update_config'); ?>
+
+    <div class="form-group">
+        <?= $form->label('example_key', t('Example Config Value')) ?>
+        <?= $form->text('example_key', $example_value) ?>
+        <p class="help-block"><?= t('This is an example config value and not used in anywhere.') ?></p>
+    </div>
+
+    <div class="ccm-dashboard-form-actions-wrapper">
+        <div class="ccm-dashboard-form-actions">
+            <button type="submit" class="btn btn-primary float-end">
+                <?php echo t('Save') ?>
+            </button>
+        </div>
+    </div>
+</form>

single_pages/dashboard/system/boilerplate/view.php

@@ -0,0 +1,2 @@
+<?php
+defined('C5_EXECUTE') or die('Access Denied.');