From fb321fa034c12369658ecd9c36ee4ec7751bea75 Mon Sep 17 00:00:00 2001
From: Eric <eric.espie@combodo.com>
Date: Fri, 26 Feb 2021 16:47:02 +0100
Subject: [PATCH] Fix ContextTag usage, and add some explanations on the
 declaration of ContextTag

---
 core/contexttag.class.inc.php            | 18 ++++++++++++++++++
 datamodels/2.x/itop-core-update/ajax.php |  4 +++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/core/contexttag.class.inc.php b/core/contexttag.class.inc.php
index 488ad1fa1..5176c3b52 100644
--- a/core/contexttag.class.inc.php
+++ b/core/contexttag.class.inc.php
@@ -20,6 +20,24 @@
 /**
  * Simple helper class for keeping track of the context inside the call stack
  *
+ * Beware:
+ * As the destructor removes the last context, don't use the same variable if you want to keep your context.
+ *      $oCtx = new ContextTag("Tag1");
+ *      $oCtx = new ContextTag("Tag2");  // Bad the destructor will remove "Tag2"
+ *      $oCtx = new ContextTag("Tag3");  // Bad the destructor will remove "Tag3"
+ *
+ * Instead, use separate variables:
+ *      $oCtx1 = new ContextTag("Tag1");
+ *      $oCtx2 = new ContextTag("Tag2");
+ *      $oCtx3 = new ContextTag("Tag3");
+ *
+ * And don't forget that any destructor (of $oCtx1, $oCtx2 or $oCtx3) will remove the LAST added tag ("Tag3" in our example)
+ *
+ * If you want to declare permanent contexts (request lifetime) you should use:
+ *      ContextTag::AddContext("Tag1");
+ *      ContextTag::AddContext("Tag2");
+ *      ContextTag::AddContext("Tag3");
+ *
  * To check (anywhere in the code) if a particular context tag is present
  * in the call stack simply do:
  *
diff --git a/datamodels/2.x/itop-core-update/ajax.php b/datamodels/2.x/itop-core-update/ajax.php
index ce60866ef..6a644b5de 100644
--- a/datamodels/2.x/itop-core-update/ajax.php
+++ b/datamodels/2.x/itop-core-update/ajax.php
@@ -23,7 +23,7 @@ require_once(MODULESROOT.'itop-core-update/src/Controller/AjaxController.php');
 
 MetaModel::LoadConfig(utils::GetConfig());
 
-new ContextTag(ContextTag::TAG_SETUP);
+$oCtxCoreUpdate = new ContextTag(ContextTag::TAG_SETUP);
 
 $oUpdateController = new AjaxController(MODULESROOT.'itop-core-update/view', 'itop-core-update');
 $oUpdateController->DisableInDemoMode();
@@ -32,3 +32,5 @@ $oUpdateController->AllowOnlyAdmin();
 // Allow parallel execution of ajax requests
 session_write_close();
 $oUpdateController->HandleAjaxOperation();
+
+unset($oCtxCoreUpdate);