Show the version conflict message on a separate page (see #809).

src/Resources/contao/classes/Versions.php

@@ -58,14 +58,22 @@ class Versions extends \Controller
 	 *
 	 * @param string  $strTable
 	 * @param integer $intPid
+	 *
+	 * @throws \InvalidArgumentException
 	 */
 	public function __construct($strTable, $intPid)
 	{
 		$this->import('Database');
 		parent::__construct();
 
+		$this->loadDataContainer($strTable);
+
+		if (!isset($GLOBALS['TL_DCA'][$strTable])) {
+			throw new \InvalidArgumentException(sprintf('"%s" is not a valid table', StringUtil::specialchars($strTable)));
+		}
+
 		$this->strTable = $strTable;
-		$this->intPid = $intPid;
+		$this->intPid = (int) $intPid;
 	}
 
 
@@ -318,8 +326,6 @@ public function restore($intVersion)
 		// Unset fields that do not exist (see #5219)
 		$data = array_intersect_key($data, $arrFields);
 
-		$this->loadDataContainer($this->strTable);
-
 		// Reset fields added after storing the version to their default value (see #7755)
 		foreach (array_diff_key($arrFields, $data) as $k=>$v)
 		{
@@ -378,8 +384,14 @@ public function restore($intVersion)
 
 	/**
 	 * Compare versions
+	 *
+	 * @param bool $blnReturnBuffer
+	 *
+	 * @return string
+	 *
+	 * @throws ResponseException
 	 */
-	public function compare()
+	public function compare($blnReturnBuffer=false)
 	{
 		$strBuffer = '';
 		$arrVersions = array();
@@ -454,7 +466,6 @@ public function compare()
 			if ($intTo > 0 && $intFrom > 0)
 			{
 				\System::loadLanguageFile($this->strTable);
-				$this->loadDataContainer($this->strTable);
 
 				// Get the order fields
 				$objDcaExtractor = \DcaExtractor::getInstance($this->strTable);
@@ -541,6 +552,11 @@ public function compare()
 			$strBuffer = '<p>'.$GLOBALS['TL_LANG']['MSC']['identicalVersions'].'</p>';
 		}
 
+		if ($blnReturnBuffer)
+		{
+			return $strBuffer;
+		}
+
 		/** @var BackendTemplate|object $objTemplate */
 		$objTemplate = new \BackendTemplate('be_diff');
 

src/Resources/contao/drivers/DC_Table.php

@@ -12,6 +12,7 @@
 
 use Contao\CoreBundle\Exception\AccessDeniedException;
 use Contao\CoreBundle\Exception\InternalServerErrorException;
+use Contao\CoreBundle\Exception\ResponseException;
 use Patchwork\Utf8;
 use Symfony\Component\HttpFoundation\Session\Attribute\AttributeBagInterface;
 use Symfony\Component\HttpFoundation\Session\SessionInterface;
@@ -2212,8 +2213,22 @@ public function edit($intId=null, $ajaxId=null)
 			// Show a warning if the record has been saved by another user (see #8412)
 			if ($intLatestVersion !== null && isset($_POST['VERSION_NUMBER']) && $intLatestVersion > \Input::post('VERSION_NUMBER'))
 			{
-				\Message::addError(sprintf($GLOBALS['TL_LANG']['ERR']['versionWarning'], $intLatestVersion, \Input::post('VERSION_NUMBER')));
-				$this->reload();
+				/** @var BackendTemplate|object $objTemplate */
+				$objTemplate = new \BackendTemplate('be_conflict');
+
+				$objTemplate->language = $GLOBALS['TL_LANGUAGE'];
+				$objTemplate->title = StringUtil::specialchars($GLOBALS['TL_LANG']['MSC']['versionConflict']);
+				$objTemplate->theme = \Backend::getTheme();
+				$objTemplate->charset = \Config::get('characterSet');
+				$objTemplate->base = \Environment::get('base');
+				$objTemplate->h1 = $GLOBALS['TL_LANG']['MSC']['versionConflict'];
+				$objTemplate->explain1 = sprintf($GLOBALS['TL_LANG']['MSC']['versionConflict1'], $intLatestVersion, \Input::post('VERSION_NUMBER'));
+				$objTemplate->explain2 = sprintf($GLOBALS['TL_LANG']['MSC']['versionConflict2'], $intLatestVersion + 1, $intLatestVersion);
+				$objTemplate->diff = $objVersions->compare(true);
+				$objTemplate->href = \Environment::get('request');
+				$objTemplate->button = $GLOBALS['TL_LANG']['MSC']['continue'];
+
+				throw new ResponseException($objTemplate->getResponse());
 			}
 
 			// Redirect

src/Resources/contao/languages/en/default.xlf

@@ -212,9 +212,6 @@
       <trans-unit id="ERR.invalidFieldName">
         <source>Please enter only the following characters: A-Z0-9[]_-</source>
       </trans-unit>
-      <trans-unit id="ERR.versionWarning">
-        <source>Another user has created version %s while you were editing version %s of this record.</source>
-      </trans-unit>
       <trans-unit id="SEC.question1">
         <source>Please add %d and %d.</source>
       </trans-unit>
@@ -1688,6 +1685,15 @@ This e-mail has been generated by Contao. You can not reply to it directly.
       <trans-unit id="MSC.invalidTokenUrl">
         <source>Invalid token</source>
       </trans-unit>
+      <trans-unit id="MSC.versionConflict">
+        <source>Version conflict</source>
+      </trans-unit>
+      <trans-unit id="MSC.versionConflict1">
+        <source>Another user has created version %s while you were editing version %s of this record.</source>
+      </trans-unit>
+      <trans-unit id="MSC.versionConflict2">
+        <source>Your changes have been now been saved as version %s and have potentially overwritten the changes of version %s, therefore please compare the versions below:</source>
+      </trans-unit>
       <trans-unit id="MSC.dragItemsHint">
         <source>Drag the items to re-order them</source>
       </trans-unit>

src/Resources/contao/templates/backend/be_conflict.html5

@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html lang="<?= $this->language ?>">
+<head>
+
+  <meta charset="<?= $this->charset ?>">
+  <title><?= $this->title ?> - Contao Open Source CMS</title>
+  <base href="<?= $this->base ?>">
+  <meta name="generator" content="Contao Open Source CMS">
+  <meta name="viewport" content="width=device-width,initial-scale=1.0,shrink-to-fit=no">
+  <meta name="referrer" content="origin">
+
+  <link rel="stylesheet" href="<?= TL_ASSETS_URL ?>system/themes/<?= $this->theme ?>/fonts.css">
+  <link rel="stylesheet" href="<?= TL_ASSETS_URL ?>system/themes/<?= $this->theme ?>/basic.css">
+  <link rel="stylesheet" href="<?= TL_ASSETS_URL ?>system/themes/<?= $this->theme ?>/diff.css">
+  <link rel="stylesheet" href="<?= TL_ASSETS_URL ?>system/themes/<?= $this->theme ?>/conflict.css">
+  <?= $this->stylesheets ?>
+
+  <script><?= $this->getLocaleString() ?></script>
+  <script src="<?= TL_ASSETS_URL ?>assets/mootools/js/mootools.min.js"></script>
+  <script src="<?= TL_ASSETS_URL ?>bundles/contaocore/mootao.min.js"></script>
+  <script src="<?= TL_ASSETS_URL ?>bundles/contaocore/core.min.js"></script>
+  <script><?= $this->getDateString() ?></script>
+  <?= $this->javascripts ?>
+
+</head>
+<body class="<?= $this->ua ?>">
+
+  <div id="container" class="cf">
+    <div id="main">
+      <h1><?= $this->h1 ?></h1>
+      <p><?= $this->explain1 ?></p>
+      <p><?= $this->explain2 ?></p>
+      <div id="diff"><?= $this->diff ?></div>
+      <p><a href="<?= $this->href ?>" class="tl_submit"><?= $this->button ?></a></p>
+    </div>
+  </div>
+
+</body>
+</html>

src/Resources/contao/themes/flexible/src/conflict.css

@@ -0,0 +1,54 @@
+/**
+ * Contao Open Source CMS
+ *
+ * Copyright (c) 2005-2017 Leo Feyer
+ *
+ * @license LGPL-3.0+
+ */
+
+/* Body */
+body {
+	background:#eaeaea url("icons/stop.svg") center 3em no-repeat;
+}
+
+/* Container */
+#container {
+	width:640px;
+	margin:14em auto 0;
+	background:#fff;
+}
+#main {
+	padding-bottom:6px;
+}
+
+/* Elements */
+h1 {
+	padding:14px 18px 12px;
+	line-height:22px;
+	border-bottom:1px solid #ddd;
+}
+p {
+	line-height:1.3;
+}
+p a {
+	vertical-align:middle;
+}
+#diff {
+	margin:18px 0;
+}
+#diff,#main > p {
+	padding-left:18px;
+	padding-right:18px;
+}
+#main > p:first-of-type {
+	margin:18px 0 9px;
+}
+
+/* Handheld */
+@media (max-width:767px) {
+	#container {
+		width:auto;
+		margin-left:10px;
+		margin-right:10px;
+	}
+}