synchro improvements:

- able to sync metadata at the same time as the files/dirs
- by default empty metadata does not overwrite database infos (checkbox can switch to previous behaviour) (bug 132)
- the form is shown again even after a successfull non simulated run

git-svn-id: http://piwigo.org/svn/trunk@2491 68402e56-0260-453c-a942-63ccdbb3a9ee

3 files changed, 188 insertions, 224 deletions

diff --git a/admin/include/functions.php b/admin/include/functions.php
index db95ab383..e700d662e 100644
--- a/admin/include/functions.php
+++ b/admin/include/functions.php
@@ -377,7 +377,7 @@ function mass_inserts($table_name, $dbfields, $datas)
   {
     $first = true;
 
-    $query = 'SHOW VARIABLES LIKE \'max_allowed_packet\';';
+    $query = 'SHOW VARIABLES LIKE \'max_allowed_packet\'';
     list(, $packet_size) = mysql_fetch_row(pwg_query($query));
     $packet_size = $packet_size - 2000; // The last list of values MUST not exceed 2000 character*/
     $query = '';
@@ -386,8 +386,6 @@ function mass_inserts($table_name, $dbfields, $datas)
     {
       if (strlen($query) >= $packet_size)
       {
-        $query .= '
-;';
         pwg_query($query);
         $first = true;
       }
@@ -425,57 +423,53 @@ INSERT INTO '.$table_name.'
       }
       $query .= ')';
     }
-
-    $query .= '
-;';
     pwg_query($query);
   }
 }
 
+define('MASS_UPDATES_SKIP_EMPTY', 1);
 /**
  * updates multiple lines in a table
  *
  * @param string table_name
  * @param array dbfields
  * @param array datas
+ * @param int flags - if MASS_UPDATES_SKIP_EMPTY - empty values do not overwrite existing ones
  * @return void
  */
-function mass_updates($tablename, $dbfields, $datas)
+function mass_updates($tablename, $dbfields, $datas, $flags=0)
 {
-  if (count($datas) != 0)
-  {
-    // depending on the MySQL version, we use the multi table update or N
-    // update queries
-    if (count($datas) < 10 or version_compare(mysql_get_server_info(), '4.0.4') < 0)
+  if (count($datas) == 0)
+    return;
+  // depending on the MySQL version, we use the multi table update or N update queries
+  if (count($datas) < 10 or version_compare(mysql_get_server_info(), '4.0.4') < 0)
+  { // MySQL is prior to version 4.0.4, multi table update feature is not available
+    foreach ($datas as $data)
     {
-      // MySQL is prior to version 4.0.4, multi table update feature is not
-      // available
-      foreach ($datas as $data)
-      {
-        $query = '
+      $query = '
 UPDATE '.$tablename.'
   SET ';
-        $is_first = true;
-        foreach ($dbfields['update'] as $key)
+      $is_first = true;
+      foreach ($dbfields['update'] as $key)
+      {
+        $separator = $is_first ? '' : ",\n    ";
+
+        if (isset($data[$key]) and $data[$key] != '')
         {
-          if (!$is_first)
-          {
-            $query.= ",\n      ";
-          }
-          $query.= $key.' = ';
-          if (isset($data[$key]) and $data[$key] != '')
-          {
-            $query.= '\''.$data[$key].'\'';
-          }
-          else
-          {
-            $query.= 'NULL';
-          }
-          $is_first = false;
+          $query.= $separator.$key.' = \''.$data[$key].'\'';
+        }
+        else
+        {
+          if ($flags & MASS_UPDATES_SKIP_EMPTY )
+            continue; // next field
+          $query.= "$separator$key = NULL";
         }
+        $is_first = false;
+      }
+      if (!$is_first)
+      {// only if one field at least updated
         $query.= '
   WHERE ';
-
         $is_first = true;
         foreach ($dbfields['primary'] as $key)
         {
@@ -493,87 +487,83 @@ UPDATE '.$tablename.'
           }
           $is_first = false;
         }
-        $query.= '
-;';
         pwg_query($query);
       }
-    }
-    else
+    } // foreach update
+  } // if mysql_ver or count<X
+  else
+  {
+    // creation of the temporary table
+    $query = '
+SHOW FULL COLUMNS FROM '.$tablename;
+    $result = pwg_query($query);
+    $columns = array();
+    $all_fields = array_merge($dbfields['primary'], $dbfields['update']);
+    while ($row = mysql_fetch_array($result))
     {
-      // creation of the temporary table
-      $query = '
-SHOW FULL COLUMNS FROM '.$tablename.'
-;';
-      $result = pwg_query($query);
-      $columns = array();
-      $all_fields = array_merge($dbfields['primary'], $dbfields['update']);
-      while ($row = mysql_fetch_array($result))
+      if (in_array($row['Field'], $all_fields))
       {
-        if (in_array($row['Field'], $all_fields))
-        {
-          $column = $row['Field'];
-          $column.= ' '.$row['Type'];
+        $column = $row['Field'];
+        $column.= ' '.$row['Type'];
 
-          $nullable = true;
-          if (!isset($row['Null']) or $row['Null'] == '' or $row['Null']=='NO')
-          {
-            $column.= ' NOT NULL';
-            $nullable = false;
-          }
-          if (isset($row['Default']))
-          {
-            $column.= " default '".$row['Default']."'";
-          }
-          elseif ($nullable)
-          {
-            $column.= " default NULL";
-          }
-          if (isset($row['Collation']) and $row['Collation'] != 'NULL')
-          {
-            $column.= " collate '".$row['Collation']."'";
-          }
-          array_push($columns, $column);
+        $nullable = true;
+        if (!isset($row['Null']) or $row['Null'] == '' or $row['Null']=='NO')
+        {
+          $column.= ' NOT NULL';
+          $nullable = false;
         }
+        if (isset($row['Default']))
+        {
+          $column.= " default '".$row['Default']."'";
+        }
+        elseif ($nullable)
+        {
+          $column.= " default NULL";
+        }
+        if (isset($row['Collation']) and $row['Collation'] != 'NULL')
+        {
+          $column.= " collate '".$row['Collation']."'";
+        }
+        array_push($columns, $column);
       }
+    }
 
-      $temporary_tablename = $tablename.'_'.micro_seconds();
+    $temporary_tablename = $tablename.'_'.micro_seconds();
 
-      $query = '
-  CREATE TABLE '.$temporary_tablename.'
-  (
-  '.implode(",\n", $columns).',
+    $query = '
+CREATE TABLE '.$temporary_tablename.'
+(
+  '.implode(",\n  ", $columns).',
   UNIQUE KEY the_key ('.implode(',', $dbfields['primary']).')
-  )
-;';
+)';
 
-      pwg_query($query);
-      mass_inserts($temporary_tablename, $all_fields, $datas);
-      // update of images table by joining with temporary table
-      $query = '
+    pwg_query($query);
+    mass_inserts($temporary_tablename, $all_fields, $datas);
+    if ( $flags & MASS_UPDATES_SKIP_EMPTY )
+      $func_set = create_function('$s', 'return "t1.$s = IFNULL(t2.$s, t1.$s)";');
+    else
+      $func_set = create_function('$s', 'return "t1.$s = t2.$s";');
+
+    // update of images table by joining with temporary table
+    $query = '
 UPDATE '.$tablename.' AS t1, '.$temporary_tablename.' AS t2
   SET '.
-        implode(
-          "\n    , ",
-          array_map(
-            create_function('$s', 'return "t1.$s = t2.$s";'),
-            $dbfields['update']
-            )
-          ).'
+      implode(
+        "\n    , ",
+        array_map($func_set,$dbfields['update'])
+        ).'
   WHERE '.
-        implode(
-          "\n    AND ",
-          array_map(
-            create_function('$s', 'return "t1.$s = t2.$s";'),
-            $dbfields['primary']
-            )
-          ).'
-  ;';
-      pwg_query($query);
-      $query = '
-DROP TABLE '.$temporary_tablename.'
-;';
-      pwg_query($query);
-    }
+      implode(
+        "\n    AND ",
+        array_map(
+          create_function('$s', 'return "t1.$s = t2.$s";'),
+          $dbfields['primary']
+          )
+        );
+    pwg_query($query);
+    $query = '
+DROP TABLE '.$temporary_tablename;
+    pwg_query($query);
   }
 }
 
@@ -587,8 +577,7 @@ function update_global_rank()
   $query = '
 SELECT id, if(id_uppercat is null,\'\',id_uppercat) AS id_uppercat, uppercats, rank, global_rank
   FROM '.CATEGORIES_TABLE.'
-  ORDER BY id_uppercat,rank,name
-;';
+  ORDER BY id_uppercat,rank,name';
 
   $cat_map = array();
 
@@ -657,6 +646,7 @@ function set_cat_visible($categories, $value)
 {
   if (!in_array($value, array('true', 'false')))
   {
+    trigger_error("set_cat_visible invalid param $value", E_USER_WARNING);
     return false;
   }
 
@@ -667,8 +657,7 @@ function set_cat_visible($categories, $value)
     $query = '
 UPDATE '.CATEGORIES_TABLE.'
   SET visible = \'true\'
-  WHERE id IN ('.implode(',', $uppercats).')
-;';
+  WHERE id IN ('.implode(',', $uppercats).')';
     pwg_query($query);
   }
   // locking a category   => all its child categories become locked
@@ -678,8 +667,7 @@ UPDATE '.CATEGORIES_TABLE.'
     $query = '
 UPDATE '.CATEGORIES_TABLE.'
   SET visible = \'false\'
-  WHERE id IN ('.implode(',', $subcats).')
-;';
+  WHERE id IN ('.implode(',', $subcats).')';
     pwg_query($query);
   }
 }
@@ -695,6 +683,7 @@ function set_cat_status($categories, $value)
 {
   if (!in_array($value, array('public', 'private')))
   {
+    trigger_error("set_cat_status invalid param $value", E_USER_WARNING);
     return false;
   }
 
@@ -716,8 +705,7 @@ UPDATE '.CATEGORIES_TABLE.'
     $query = '
 UPDATE '.CATEGORIES_TABLE.'
   SET status = \'private\'
-  WHERE id IN ('.implode(',', $subcats).')
-;';
+  WHERE id IN ('.implode(',', $subcats).')';
     pwg_query($query);
   }
 }
@@ -1582,7 +1570,7 @@ function do_maintenance_all_tables()
   $all_tables = array();
 
   // List all tables
-  $query = 'SHOW TABLES LIKE \''.$prefixeTable.'%\';';
+  $query = 'SHOW TABLES LIKE \''.$prefixeTable.'%\'';
   $result = pwg_query($query);
   while ($row = mysql_fetch_array($result))
   {
@@ -1590,7 +1578,7 @@ function do_maintenance_all_tables()
   }
 
   // Repair all tables
-  $query = 'REPAIR TABLE '.implode(', ', $all_tables).';';
+  $query = 'REPAIR TABLE '.implode(', ', $all_tables);
   $mysql_rc = pwg_query($query);
 
   // Re-Order all tables
@@ -1616,7 +1604,7 @@ function do_maintenance_all_tables()
   }
 
   // Optimize all tables
-  $query = 'OPTIMIZE TABLE '.implode(', ', $all_tables).';';
+  $query = 'OPTIMIZE TABLE '.implode(', ', $all_tables);
   $mysql_rc = $mysql_rc && pwg_query($query);
   if ($mysql_rc)
   {
@@ -1832,8 +1820,7 @@ function invalidate_user_cache()
 {
   $query = '
 UPDATE '.USER_CACHE_TABLE.'
-  SET need_update = \'true\'
-;';
+  SET need_update = \'true\'';
   pwg_query($query);
   trigger_action('invalidate_user_cache');
 }
diff --git a/admin/site_update.php b/admin/site_update.php
index e6fb6d4ef..ba406afe4 100644
--- a/admin/site_update.php
+++ b/admin/site_update.php
@@ -42,8 +42,7 @@ $site_id = $_GET['site'];
 $query='
 SELECT galleries_url
   FROM '.SITES_TABLE.'
-  WHERE id = '.$site_id.'
-;';
+  WHERE id = '.$site_id;
 list($site_url) = mysql_fetch_row(pwg_query($query));
 if (!isset($site_url))
 {
@@ -139,8 +138,6 @@ if (isset($_POST['submit'])
 {
   $start = get_moment();
   // which categories to update ?
-  $cat_ids = array();
-
   $query = '
 SELECT id, uppercats, global_rank, status, visible
   FROM '.CATEGORIES_TABLE.'
@@ -161,15 +158,7 @@ SELECT id, uppercats, global_rank, status, visible
 ';
     }
   }
-  $query.= '
-;';
-  $result = pwg_query($query);
-
-  $db_categories = array();
-  while ($row = mysql_fetch_array($result))
-  {
-    $db_categories[$row['id']] = $row;
-  }
+  $db_categories = hash_from_query($query, 'id');
 
   // get categort full directories in an array for comparison with file
   // system directory tree
@@ -194,8 +183,7 @@ SELECT id, uppercats, global_rank, status, visible
 
   $query = '
 SELECT id
-  FROM '.CATEGORIES_TABLE.'
-;';
+  FROM '.CATEGORIES_TABLE;
   $result = pwg_query($query);
   while ($row = mysql_fetch_array($result))
   {
@@ -206,8 +194,7 @@ SELECT id
   $query = '
 SELECT id_uppercat, MAX(rank)+1 AS next_rank
   FROM '.CATEGORIES_TABLE.'
-  GROUP BY id_uppercat
-;';
+  GROUP BY id_uppercat';
   $result = pwg_query($query);
   while ($row = mysql_fetch_array($result))
   {
@@ -222,8 +209,7 @@ SELECT id_uppercat, MAX(rank)+1 AS next_rank
   // next category id available
   $query = '
 SELECT IF(MAX(id)+1 IS NULL, 1, MAX(id)+1) AS next_id
-  FROM '.CATEGORIES_TABLE.'
-;';
+  FROM '.CATEGORIES_TABLE;
   list($next_id) = mysql_fetch_array(pwg_query($query));
 
   // retrieve sub-directories fulldirs from the site reader
@@ -388,13 +374,8 @@ SELECT id, path
         implode(', ', $cat_ids),
         80,
         "\n"
-        ).')
-;';
-    $result = pwg_query($query);
-    while ($row = mysql_fetch_array($result))
-    {
-      $db_elements[$row['id']] = $row['path'];
-    }
+        ).')';
+    $db_elements = simple_hash_from_query($query, 'id', 'path');
 
     // searching the unvalidated waiting elements (they must not be taken into
     // account)
@@ -403,8 +384,7 @@ SELECT file,storage_category_id
   FROM '.WAITING_TABLE.'
   WHERE storage_category_id IN (
 '.wordwrap(implode(', ', $cat_ids), 80, "\n").')
-    AND validated = \'false\'
-;';
+    AND validated = \'false\'';
     $result = pwg_query($query);
     while ($row = mysql_fetch_array($result))
     {
@@ -421,8 +401,7 @@ SELECT file,storage_category_id
   // next element id available
   $query = '
 SELECT IF(MAX(id)+1 IS NULL, 1, MAX(id)+1) AS next_element_id
-  FROM '.IMAGES_TABLE.'
-;';
+  FROM '.IMAGES_TABLE;
   list($next_element_id) = mysql_fetch_array(pwg_query($query));
 
   $start = get_moment();
@@ -564,8 +543,7 @@ SELECT id,file,storage_category_id,infos
   FROM '.WAITING_TABLE.'
   WHERE storage_category_id IN (
 '.wordwrap(implode(', ', $cat_ids), 80, "\n").')
-    AND validated = \'true\'
-;';
+    AND validated = \'true\'';
     $result = pwg_query($query);
 
     $datas = array();
@@ -585,8 +563,7 @@ SELECT id,file,storage_category_id,infos
 SELECT id
   FROM '.IMAGES_TABLE.'
   WHERE storage_category_id = '.$row['storage_category_id'].'
-    AND file = \''.$row['file'].'\'
-;';
+    AND file = \''.$row['file'].'\'';
       list($data['id']) = mysql_fetch_array(pwg_query($query));
 
       foreach ($fields['update'] as $field)
@@ -723,18 +700,11 @@ if (isset($_POST['submit'])
 // +-----------------------------------------------------------------------+
 // |                          synchronize metadata                         |
 // +-----------------------------------------------------------------------+
-if (isset($_POST['submit']) and preg_match('/^metadata/', $_POST['sync'])
+if (isset($_POST['submit']) and isset($_POST['sync_meta'])
          and !$general_failure)
 {
   // sync only never synchronized files ?
-  if ($_POST['sync'] == 'metadata_new')
-  {
-    $opts['only_new'] = true;
-  }
-  else
-  {
-    $opts['only_new'] = false;
-  }
+  $opts['only_new'] = isset($_POST['meta_all']) ? false : true;
   $opts['category_id'] = '';
   $opts['recursive'] = true;
 
@@ -776,14 +746,8 @@ SELECT id
   WHERE has_high = \'true\'
     AND id IN (
 '.wordwrap(implode(', ', $image_ids), 80, "\n").'
-)
-;';
-
-    $result = pwg_query($query);
-    while ($row = mysql_fetch_array($result))
-    {
-      array_push($has_high_images, $row['id']);
-    }
+)';
+    $has_high_images = array_from_query($query, 'id' );
   }
 
   foreach ( $files as $id=>$file )
@@ -843,7 +807,8 @@ SELECT id
               array('date_metadata_update'))
             )
           ),
-        $datas
+        $datas,
+        isset($_POST['meta_empty_overrides']) ? 0 : MASS_UPDATES_SKIP_EMPTY
         );
     }
     set_tags_of($tags_of);
@@ -893,58 +858,61 @@ $template->assign(
 // +-----------------------------------------------------------------------+
 // |                        introduction : choices                         |
 // +-----------------------------------------------------------------------+
-if (!isset($_POST['submit']) or (isset($simulate) and $simulate))
+if (isset($_POST['submit']))
 {
-  if (isset($simulate) and $simulate)
-  {
-    $tpl_introduction = array(
-        'sync'  => $_POST['sync'],
-        'display_info' => isset($_POST['display_info']) and $_POST['display_info']==1,
-        'add_to_caddie' => isset($_POST['add_to_caddie']) and $_POST['add_to_caddie']==1,
-        'subcats_included' => isset($_POST['subcats-included']) and $_POST['subcats-included']==1,
-        'privacy_level_selected' => (int)@$_POST['privacy_level'],
-      );
+  $tpl_introduction = array(
+      'sync'  => $_POST['sync'],
+      'sync_meta'  => isset($_POST['sync_meta']) ? true : false,
+      'display_info' => isset($_POST['display_info']) and $_POST['display_info']==1,
+      'add_to_caddie' => isset($_POST['add_to_caddie']) and $_POST['add_to_caddie']==1,
+      'subcats_included' => isset($_POST['subcats-included']) and $_POST['subcats-included']==1,
+      'privacy_level_selected' => (int)@$_POST['privacy_level'],
+      'meta_all'  => isset($_POST['meta_all']) ? true : false,
+      'meta_empty_overrides'  => isset($_POST['meta_empty_overrides']) ? true : false,
+    );
 
-    if (isset($_POST['cat']) and is_numeric($_POST['cat']))
-    {
-      $cat_selected = array($_POST['cat']);
-    }
-    else
-    {
-      $cat_selected = array();
-    }
+  if (isset($_POST['cat']) and is_numeric($_POST['cat']))
+  {
+    $cat_selected = array($_POST['cat']);
   }
   else
   {
-    $tpl_introduction = array(
-        'sync'  => 'dirs',
-        'display_info' => false,
-        'add_to_caddie' => false,
-        'subcats_included' => true,
-        'privacy_level_selected' => 0,
-      );
-
     $cat_selected = array();
   }
+}
+else
+{
+  $tpl_introduction = array(
+      'sync'  => 'dirs',
+      'sync_meta'  => true,
+      'display_info' => false,
+      'add_to_caddie' => false,
+      'subcats_included' => true,
+      'privacy_level_selected' => 0,
+      'meta_all'  => false,
+      'meta_empty_overrides'  => false,
+    );
+
+  $cat_selected = array();
+}
 
-  $tpl_introduction['privacy_level_options']=array();
-  foreach ($conf['available_permission_levels'] as $level)
-  {
-    $tpl_introduction['privacy_level_options'][$level] = l10n( sprintf('Level %d', $level) );
-  }
+$tpl_introduction['privacy_level_options']=array();
+foreach ($conf['available_permission_levels'] as $level)
+{
+  $tpl_introduction['privacy_level_options'][$level] = l10n( sprintf('Level %d', $level) );
+}
 
-  $template->assign('introduction', $tpl_introduction);
+$template->assign('introduction', $tpl_introduction);
 
-  $query = '
+$query = '
 SELECT id,name,uppercats,global_rank
   FROM '.CATEGORIES_TABLE.'
-  WHERE site_id = '.$site_id.'
-;';
-  display_select_cat_wrapper($query,
-                             $cat_selected,
-                             'category_options',
-                             false);
-}
+  WHERE site_id = '.$site_id;
+display_select_cat_wrapper($query,
+                           $cat_selected,
+                           'category_options',
+                           false);
+
 
 if (count($errors) > 0)
 {
diff --git a/admin/template/yoga/admin/site_update.tpl b/admin/template/yoga/admin/site_update.tpl
index e3016c68b..ad4f99e0f 100644
--- a/admin/template/yoga/admin/site_update.tpl
+++ b/admin/template/yoga/admin/site_update.tpl
@@ -58,25 +58,34 @@
 <h3>{'update_default_title'|@translate}</h3>
 <form action="" method="post" id="update">
 
-  <fieldset id="syncFiles">
-    <legend>{'update_sync_files'|@translate}</legend>
-    <ul>
-      <li><label><input type="radio" name="sync" value="dirs" {if 'dirs'==$introduction.sync}checked="checked"{/if}/> {'update_sync_dirs'|@translate}</label></li>
-      <li><label><input type="radio" name="sync" value="files" {if 'files'==$introduction.sync}checked="checked"{/if}/> {'update_sync_all'|@translate}</label></li>
-      <li><label><input type="checkbox" name="display_info" value="1" {if $introduction.display_info}checked="checked"{/if}/> {'update_display_info'|@translate}</label></li>
-      <li><label><input type="checkbox" name="add_to_caddie" value="1" {if $introduction.add_to_caddie}checked="checked"{/if}/> {'add new elements to caddie'|@translate}</label></li>
-      <li><label>{'Minimum privacy level'|@translate} <select name="privacy_level">{html_options options=$introduction.privacy_level_options selected=$introduction.privacy_level_selected}</select></label></li>
-    </ul>
-  </fieldset>
+	<fieldset id="syncFiles">
+		<legend>{'update_sync_files'|@translate}</legend>
+		<ul>
+			<li><label><input type="radio" name="sync" value="" {if empty($introduction.sync)}checked="checked"{/if}/> {'nothing'|@translate}</label></li>
+			<li><label><input type="radio" name="sync" value="dirs" {if 'dirs'==$introduction.sync}checked="checked"{/if}/> {'update_sync_dirs'|@translate}</label></li>
 
-  <fieldset id="syncMetadata">
-    <legend>{'update_sync_metadata'|@translate}</legend>
-    {'update_used_metadata'|@translate} : {$METADATA_LIST}.<br/>
-    <ul>
-      <li><label><input type="radio" name="sync" value="metadata_new" {if 'metadata_new'==$introduction.sync}checked="checked"{/if}/> {'update_sync_metadata_new'|@translate}</label></li>
-      <li><label><input type="radio" name="sync" value="metadata_all" {if 'metadata_all'==$introduction.sync}checked="checked"{/if}/> {'update_sync_metadata_all'|@translate}</label></li>
-    </ul>
-  </fieldset>
+			<li><label><input type="radio" name="sync" value="files" {if 'files'==$introduction.sync}checked="checked"{/if}/> {'update_sync_all'|@translate}</label>
+				<ul style="padding-left:3em">
+					<li><label><input type="checkbox" name="display_info" value="1" {if $introduction.display_info}checked="checked"{/if}/> {'update_display_info'|@translate}</label></li>
+					<li><label><input type="checkbox" name="add_to_caddie" value="1" {if $introduction.add_to_caddie}checked="checked"{/if}/> {'add new elements to caddie'|@translate}</label></li>
+					<li><label>{'Minimum privacy level'|@translate} <select name="privacy_level">{html_options options=$introduction.privacy_level_options selected=$introduction.privacy_level_selected}</select></label></li>
+				</ul>
+			</li>
+		</ul>
+	</fieldset>
+
+	<fieldset id="syncMetadata">
+		<legend>{'update_sync_metadata'|@translate}</legend>
+		<label><input type="checkbox" name="sync_meta" {if $introduction.sync_meta}checked="checked"{/if}/> {'synchronize metadata'|@translate} ({$METADATA_LIST})</label></li>
+		<ul style="padding-left:3em">
+	  		<li>
+	  			<label><input type="checkbox" name="meta_all" {if $introduction.meta_all}checked="checked"{/if}/> {'update_sync_metadata_all'|@translate}</label>
+	  		</li>
+	  		<li>
+	  			<label><input type="checkbox" name="meta_empty_overrides" {if $introduction.meta_empty_overrides}checked="checked"{/if}/> {'overrides existing values with empty ones'|@translate}</label>
+	  		</li>
+		</ul>
+	</fieldset>
 
   <fieldset id="syncSimulate">
     <legend></legend>