maybe a checkbox would be added - "Clear when unlinking template"
that would not allow fine grained control over each host, but might be just enough

Is this something we can expect to see in the next release ? This is really an annoying behavior. We shouldn't need to use the API to "unlink and clear" a template from 10 hosts (or go on each host one by one).

In certain circumstances unlinking and clearing a template on host level in frontend might be a work-around too.
Either manually or by mass update functionality.

The proposed solution seems to be unclear and uncommon for Zabbix so we wouldn't want to implement it that way. We would probably need to rethink the linkage control to find a better solution.

note that such a checkbox would be very similar to template control in mass update form

A checkbox might be enough. In fact, if you have a medium to big environment, you never want to create items attached to hosts, all is done with templates. You can mass link a template to multiple hosts easily. You can also replace or clear templates attached to hosts with the mass update form, but all the hosts should have the same templates. However, you cannot unlink and clear a template attached to multiple hosts. And if you don't clear the items when unlinking, you end up with tons of "orphaned" items, which you aren't even aware of...

In fact, I don't understand the use-case of unlinking a template WITHOUT clearing. Why would you leave the items if the template is removed ???

richlv, the template control in the mass update form updates all the templates attached to a list of hosts. If we just want to unlink one template from several hosts without affecting the other templates, we can't. We just need a "unlink and clear" button in the template properties panel.

I've seen one use case for unlinking without clearing: if two separate templates have been added to a set of hosts originally, but later it's decided to link the templates together. I don't know of a way to do this without removing the template being linked first, since the link form will complain about the template being linked to a host more than once. The only way I've found to fix this is to first unlink the template that is being linked from all hosts, and then to link the templates together. If I did an unlink and clear during this process, I would lose all previous data, which is not what I wanted. I know of no other way to perform this.

Other than that, I haven't run into the situation where unlinking without actually clearing would be the "desired" behavior.

Yes, this is really a pain for us. Imagine that a template is linked to multiple hosts and that someone unlinks it but forgets to clear the items at the same time. You end up with many hosts with many unneeded items. And there is no simple way to remove these items afterwards.
Please allow to unlink and clear multiple hosts from a template !

I've created a patch for this purpose.
It adds a "unlink and clear" checkbox in the template configuration view. Let me know if it works for you (tested in 2.2.5).

The patch2 sets the box as checked by default.

tatapoum, thanks for the patch
From my point of view 'Clear when unlinking' should not be checked by default. First it changes usual/ habitual behavior and secondly it leads to loosing data unrecoverable.
When un-linking without clearing by mistake (forgetting it) one can still re-link the template and do it right during the second attempt.

So you need to use the patch1. Hope it gets merged.
Here is how it looks like :

This third release of the patch fixed a bug with the templateID.

Hi, what is needed for this patch to get merged into the trunk ?

Hi, could you add this patch to the next release ? It's very simple but useful.

So, there is no way to see this small patch implemented at some point ? Templates are handy, but when you need to unlink a template from 100+ of hosts, this is very painful.

Here is a patch rebased on the latest trunk :

diff --git a/frontends/php/include/views/configuration.template.edit.php b/frontends/php/include/views/configuration.template.edit.php
index 4665234..8ccbeab 100644
--- a/frontends/php/include/views/configuration.template.edit.php
+++ b/frontends/php/include/views/configuration.template.edit.php
@@ -147,6 +147,15 @@ $templateList->addRow(_('Hosts / templates'), $hostsTB->Get(_('In'), array(

 $templateList->addRow(_('Description'), new CTextArea('description', $this->data['description']));

+$templatesDiv = new CDiv(array(
+                       new CCheckBox('mass_clear_hosts', $this->data['mass_clear_hosts']),
+                       SPACE,
+                       _('Clear when unlinking')
+               ), 'floatleft');
+
+$templatesDiv->setAttribute('id', 'templateDiv');
+$templateList->addRow($templatesDiv);
+
 // FULL CLONE {
 if ($data['form'] === 'full_clone') {
        // template applications
diff --git a/frontends/php/templates.php b/frontends/php/templates.php
index 44e14f0..7bfb5c4 100644
--- a/frontends/php/templates.php
+++ b/frontends/php/templates.php
@@ -56,6 +56,7 @@ $fields = array(
        'visiblename'           => array(T_ZBX_STR, O_OPT, null,                null,   'isset({add}) || isset({update})'),
        'groupid'                       => array(T_ZBX_INT, O_OPT, P_SYS,               DB_ID,  null),
        'twb_groupid'           => array(T_ZBX_INT, O_OPT, P_SYS,               DB_ID,  null),
+       'mass_clear_hosts'      => array(T_ZBX_STR, O_OPT, null,                        null,           null),
        'newgroup'                      => array(T_ZBX_STR, O_OPT, null,                null,   null),
        'description'           => array(T_ZBX_STR, O_OPT, null,                null,   null),
        'macros_rem'            => array(T_ZBX_STR, O_OPT, P_SYS|P_ACT, null,   null),
@@ -216,6 +217,13 @@ elseif (hasRequest('add') || hasRequest('update')) {
                        'templated_hosts' => true,
                        'filter' => array('flags' => ZBX_FLAG_DISCOVERY_NORMAL)
                ));
+
+               $hostIds = zbx_objectValues($dbHosts, 'hostid');
+               $templateHosts = API::Host()->get(array(
+                                               'templateids' => $templateId
+                                       ));
+               $templateHostsIds = zbx_objectValues($templateHosts, 'hostid');
+               $hostsToDelete = array_diff($templateHostsIds, $hostIds);

                // create / update template
                $template = array(
@@ -231,6 +239,18 @@ elseif (hasRequest('add') || hasRequest('update')) {
                if ($templateId) {
                        $template['templateid'] = $templateId;
                        $template['templates_clear'] = $templatesClear;
+
+                       if (isset($_REQUEST['mass_clear_hosts'])) {
+                               if ($hostsToDelete) {
+                                       $hosts = array(
+                                               'hosts' => zbx_toObject($hostsToDelete, 'hostid' ),
+                                               'templates_clear' => array('templateid' => $templateId)
+                                       );
+                                       if (!API::Host()->massupdate($hosts)) {
+                                               throw new Exception();
+                                       }
+                               }
+                       }

                        $messageSuccess = _('Template updated');
                        $messageFailed = _('Cannot update template');
@@ -440,7 +460,8 @@ if (hasRequest('form')) {
        $data = array(
                'form' => getRequest('form'),
                'groupId' => getRequest('groupid', 0),
-               'groupIds' => getRequest('groups', array())
+               'groupIds' => getRequest('groups', array()),
+               'mass_clear_hosts' => getRequest('mass_clear_hosts')
        );

        if ($templateId) {

Ported to 2.4.7

storex, could you please contribute your patch to https://github.com/zabbix/zabbix-patches for better visibility?

This should be added to 3.0 as well

After having this patch applied for quite a while, a Zabbix user recognized today that 'Clear when unlinking' seems not work with nested templates.

Given is:
T3 -> T2 -> T1 -> H1

Unlinking and clearing of T3 from T2 did still only unlink T3. However, I haven't investigated the details yet.

Ported to 3.2.1

Hi, storex!

I've added your patch for 2.4 and 3.2 to https://github.com/zabbix/zabbix-patches - now it could be applied easily with command-line tool.
Also, 3.2.1 patch have a mistake: it reads "--- a/include/views/templates.php <...>", should be "--- a/templates.php <...>" — I've fixed that before adding to the repo.

Patch was updated to 3.4 release version and still available by link https://github.com/zabbix/zabbix-patches.

This patch could be fixed to unlink and clear from nested templates as well and included into 4.0. It's really annoying this functionality not being available in upstream still.

8 years and not added to Zabbix 3? Please add it.

Wow, I can't believe this is not fixed yet. I have to go unlink and clear things manually still. Please help to fix it.

This functionality is not present from version 4.0. Closed as "Won't Fix".