--- loncom/html/adm/helper/newslot.helper	2011/12/18 17:15:08	1.28
+++ loncom/html/adm/helper/newslot.helper	2018/06/27 14:35:09	1.30.4.1
@@ -184,11 +184,34 @@
         delete($helper->{'VARS'}{'startreserve'});
         delete($helper->{'VARS'}{'endreserve'});
         delete($helper->{'VARS'}{'maxspace'});
-        delete($helper->{'VARS'}{'startunique'});
-        delete($helper->{'VARS'}{'endunique'});
       </exec>
+      <message>
+         </p><p>Period of time when this slot can only be uniquely assigned:<br />&nbsp;&nbsp;&nbsp;Start:
+      </message>
+      <date variable="startunique" hoursminutes="1" anytime="1">
+        <defaultvalue>
+          my $default=&{$helper->{DATA}{origslot}}('uniqueperiod','anytime');
+          if ($default eq 'anytime') { return 'anytime' };
+          if (ref($default)) { return $default->[0]; }
+          return 'anytime';
+        </defaultvalue>
+      </date>
+      <message><br />&nbsp;&nbsp;&nbsp;End: </message>
+      <date variable="endunique" hoursminutes="1" anytime="1">
+        <defaultvalue>
+          my $default=&{$helper->{DATA}{origslot}}('uniqueperiod','anytime');
+          if ($default eq 'anytime') { return 'anytime' };
+          if (ref($default)) { return $default->[1]; }
+          return 'anytime';
+        </defaultvalue>
+        <validator>
+           if (defined($val) && $val < $helper->{'VARS'}{'startunique'}) {
+               return 'End time must be later than the start time.';
+           }
+           return undef;
+        </validator>
+      </date>
     </condition>
-
     <message>
       </p><p>Proctored access:
     </message>
@@ -314,7 +337,7 @@
   </state>
 
 
-  <state name="FINISH" title="Creating/Modfying Slot">
+  <state name="FINISH" title="Creating/Modifying Slot">
 	    <message> Created Slot  </message>	
     <final>
       <finalcode>
@@ -396,6 +419,9 @@
         my $ret = &Apache::lonnet::cput('slots',
 					{$helper->{'VARS'}{'name'} => \%slot},
 					$cdom,$cname);
+        if ($ret eq 'ok') {
+            &Apache::lonnet::devalidate_slots_cache($cname,$cdom);
+        }
         $result.="\n ".'Name: '.&HTML::Entities::encode($helper->{'VARS'}{'name'}).'</li>'.
     "\n".'<li> Starts: '.&Apache::lonlocal::locallocaltime($slot{'starttime'}).'</li>'.
                  "\n".'<li> Ends: '.&Apache::lonlocal::locallocaltime($slot{'endtime'}).'</li>'.