diff --git a/website/agenda/planung/assign-series.cgi b/website/agenda/planung/assign-series.cgi
index 7adb181..c79dce0 100755
--- a/website/agenda/planung/assign-series.cgi
+++ b/website/agenda/planung/assign-series.cgi
@@ -11,6 +11,7 @@ use Encode();
 use params();
 use config();
 use log();
+use entry();
 use template();
 use auth();
 use uac();
@@ -204,15 +205,8 @@ sub check_params {
 
     my $checked = {};
 
-    #actions and roles
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(assign_series)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of( $params->{action}, ['assign_series'] );
 
-    #numeric values
     $checked->{exclude} = 0;
     entry::set_numbers( $checked, $params, [
         'id', 'project_id', 'studio_id', 'series_id'
diff --git a/website/agenda/planung/assignments.cgi b/website/agenda/planung/assignments.cgi
index f9b50da..b3d72d5 100755
--- a/website/agenda/planung/assignments.cgi
+++ b/website/agenda/planung/assignments.cgi
@@ -352,15 +352,8 @@ sub check_params {
 
     my $checked = {};
 
-    #actions and roles
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(assign_events)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of($params->{action}, ['assign_events']);
 
-    #numeric values
     $checked->{exclude} = 0;
     entry::set_numbers( $checked, $params, [
         'id', 'project_id', 'studio_id', 'series_id', 'event_id'
@@ -389,7 +382,6 @@ sub check_params {
     entry::set_numbers( $checked, $params, [
         'frequency', 'duration', 'default_duration', 'create_events', 'publish_events', 'live']);
 
-    #scalars
     entry::set_strings( $checked, $params, 
         [ 'search', 'from', 'till' ]);
 
diff --git a/website/agenda/planung/audio-recordings.cgi b/website/agenda/planung/audio-recordings.cgi
index 8d1eae5..a142df6 100755
--- a/website/agenda/planung/audio-recordings.cgi
+++ b/website/agenda/planung/audio-recordings.cgi
@@ -13,6 +13,7 @@ use File::Temp();
 
 use config();
 use log();
+use entry();
 use localization();
 use auth();
 use uac();
@@ -542,8 +543,7 @@ sub check_params {
 
     my $checked = {};
     $checked->{error} = '';
-    $checked->{template} =
-      template::check( $config, $params->{template}, 'upload-audio-recordings' );
+    $checked->{template} = template::check( $config, $params->{template}, 'upload-audio-recordings' );
 
     entry::set_numbers( $checked, $params, [
         'project_id', 'studio_id', 'default_studio_id', 'series_id', 'event_id', 'id']);
@@ -554,8 +554,11 @@ sub check_params {
         $checked->{studio_id} = -1;
     }
 
+    $checked->{action} = entry::element_of($params->{action}, 
+        ['update', 'delete']);
+
     entry::set_strings( $checked, $params, [
-        'name', 'description', 'action', 'path' ]);
+        'name', 'description', 'path' ]);
 
     $checked->{upload} = $params->{upload};
     return $checked;
diff --git a/website/agenda/planung/comment.cgi b/website/agenda/planung/comment.cgi
index a7dd5ef..3f61201 100755
--- a/website/agenda/planung/comment.cgi
+++ b/website/agenda/planung/comment.cgi
@@ -242,13 +242,8 @@ sub check_params {
 
     my $checked = {};
 
-    #actions
-
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(setLock|setRead|showComment)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of($params->{action}, 
+        [ 'setLock', 'setRead', 'showComment', 'update', 'delete']);
 
     #template
     my $template = '';
diff --git a/website/agenda/planung/create-events.cgi b/website/agenda/planung/create-events.cgi
index cf41eeb..f104988 100755
--- a/website/agenda/planung/create-events.cgi
+++ b/website/agenda/planung/create-events.cgi
@@ -202,15 +202,9 @@ sub check_params {
 
     my $checked = {};
 
-    #actions and roles
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(create_events|show_events)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of($params->{action}, 
+        ['create_events', 'show_events']);
 
-    #numeric values
     $checked->{exclude}  = 0;
     $checked->{duration} = 28;
     entry::set_numbers( $checked, $params, [
diff --git a/website/agenda/planung/event-history.cgi b/website/agenda/planung/event-history.cgi
index 6df88e6..09d52da 100755
--- a/website/agenda/planung/event-history.cgi
+++ b/website/agenda/planung/event-history.cgi
@@ -13,6 +13,7 @@ use Text::Diff::Unified::XS;
 
 use params();
 use config();
+use entry();
 use log();
 use template();
 use db();
@@ -249,7 +250,7 @@ sub check_params {
 
     #numeric values
     entry::set_numbers( $checked, $params, [
-        'id', 'project_id', 'studio_id', 'default_studio_id', 'user_id', 'series_id', 'event_id', 'v1', 'v2' )
+        'id', 'project_id', 'studio_id', 'default_studio_id', 'user_id', 'series_id', 'event_id', 'v1', 'v2'
     ]);
 
     if ( defined $checked->{studio_id} ) {
@@ -258,13 +259,8 @@ sub check_params {
         $checked->{studio_id} = -1;
     }
 
-    #actions and roles
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(show|diff)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of($params->{action}, ['show', 'diff']);
+
     return $checked;
 }
 
diff --git a/website/agenda/planung/event.cgi b/website/agenda/planung/event.cgi
index 8fc2b08..f7a2b36 100755
--- a/website/agenda/planung/event.cgi
+++ b/website/agenda/planung/event.cgi
@@ -843,13 +843,11 @@ sub check_params {
         }
     }
 
-    #actions
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        $checked->{action} = $params->{action} if List::Util::any { $_ eq $params->{action} } qw{
+    $checked->{action} = entry::element_of($params->{action}, 
+        [qw{
           save delete download show_new_event show_new_event_from_schedule
           create_event create_event_from_schedule get_json
-        };
-    }
+        }]
+    );
     return $checked;
 }
diff --git a/website/agenda/planung/image-upload.cgi b/website/agenda/planung/image-upload.cgi
index bd96d81..adeb683 100755
--- a/website/agenda/planung/image-upload.cgi
+++ b/website/agenda/planung/image-upload.cgi
@@ -370,7 +370,6 @@ sub check_params {
     my $checked = {};
     $checked->{template} = template::check( $config, $params->{template}, 'image-upload' );
 
-    #numeric values
     entry::set_numbers( $checked, $params, [
         'project_id', 'studio_id', 'default_studio_id'
     ]);
@@ -383,7 +382,6 @@ sub check_params {
 
     entry::set_strings( $checked, $params, [ 'action', 'name', 'description', 'licence' ]);
 
-    #checkboxes
     entry::set_bools( $checked, $params, [ 'public' ] );
     return $checked;
 }
diff --git a/website/agenda/planung/notify-events.cgi b/website/agenda/planung/notify-events.cgi
index cef85dc..f7fbf8b 100755
--- a/website/agenda/planung/notify-events.cgi
+++ b/website/agenda/planung/notify-events.cgi
@@ -261,14 +261,7 @@ sub check_params {
         $checked->{studio_id} = -1;
     }
 
-    #actions and roles
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(send)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
-
+    $checked->{action} = entry::element_of($params->{action}, ['send']);
     return $checked;
 }
 
diff --git a/website/agenda/planung/projects.cgi b/website/agenda/planung/projects.cgi
index 4e424e8..f0d8fe3 100755
--- a/website/agenda/planung/projects.cgi
+++ b/website/agenda/planung/projects.cgi
@@ -277,13 +277,8 @@ sub check_params {
     $template = template::check( $config, $params->{template}, 'projects' );
     $checked->{template} = $template;
 
-    #actions
-    my $action = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(save|delete|assign_studio|unassign_studio)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of($params->{action}, 
+        ['save', 'delete', 'assign_studio', 'unassign_studio'] );
 
     entry::set_strings( $checked, $params, [
         'name', 'title', 'subtitle', 'start_date', 'end_date', 'image', 'email', 'setImage' ]);
diff --git a/website/agenda/planung/request-password.cgi b/website/agenda/planung/request-password.cgi
index b1aac40..0bc8781 100755
--- a/website/agenda/planung/request-password.cgi
+++ b/website/agenda/planung/request-password.cgi
@@ -145,12 +145,7 @@ sub check_params {
     entry::set_strings( $checked, $params, [
         'user', 'token', 'user_password', 'user_password2']);
 
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(change)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of($params->{action}, ['change']);
 
     return $checked;
 }
diff --git a/website/agenda/planung/roles.cgi b/website/agenda/planung/roles.cgi
index 6c26ed1..745ba01 100755
--- a/website/agenda/planung/roles.cgi
+++ b/website/agenda/planung/roles.cgi
@@ -8,6 +8,7 @@ use Data::Dumper;
 
 use config();
 use params();
+use entry();
 use log();
 use template();
 use auth();
@@ -434,12 +435,7 @@ sub check_params {
     $template = template::check( $config, $params->{template}, 'roles.html' );
     $checked->{template} = $template;
 
-    #actions
-    if ( defined $params->{action} ) {
-        if ( $params->{action} eq 'save' ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of( $params->{action}, ['save']);
 
     entry::set_numbers( $checked, $params, [
         'project_id', 'studio_id', 'default_studio_id'
diff --git a/website/agenda/planung/series.cgi b/website/agenda/planung/series.cgi
index bd1b2db..112767c 100755
--- a/website/agenda/planung/series.cgi
+++ b/website/agenda/planung/series.cgi
@@ -1411,22 +1411,16 @@ sub check_params {
 
     my $checked = {};
 
-    #actions
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        $checked->{action} = $params->{action} if List::Util::any { $_ eq $params->{action} } qw{
-          add_user remove_user
+    $checked->{action} = entry::element_of( $params->{action}, 
+    [ qw( add_user remove_user
           create delete save details show
           save_schedule delete_schedule
           save_scan scan_events
           assign_event unassign_event reassign_event
           rebuild_episodes set_rebuilt_episodes
-        };
-    }
-
-    #numeric values
+    )]);
+    
     $checked->{exclude} = 0;
-    $checked->{action}  = $params->{action};
     entry::set_numbers( $checked, $params, [
         'id',            'project_id',
         'studio_id',     'default_studio_id',
diff --git a/website/agenda/planung/show-image.cgi b/website/agenda/planung/show-image.cgi
index 8c95be9..a2fd6f8 100755
--- a/website/agenda/planung/show-image.cgi
+++ b/website/agenda/planung/show-image.cgi
@@ -100,7 +100,6 @@ sub check_params {
 
     my $checked = {};
 
-    #numeric values
     for my $param ('filename') {
         if ( ( defined $params->{$param} ) && ( $params->{$param} =~ /^[A-Za-z\_\-\.\d\/]+$/ ) ) {
             $checked->{$param} = $params->{$param};
@@ -115,10 +114,9 @@ sub check_params {
         }
     }
 
-    #numeric values
     entry::set_numbers( $checked, $params, [
         'project_id', 'studio_id', 'series_id', 'event_id'
-    ])
+    ]);
 
     if ( defined $checked->{studio_id} ) {
         $checked->{default_studio_id} = $checked->{studio_id};
diff --git a/website/agenda/planung/studios.cgi b/website/agenda/planung/studios.cgi
index bb1a7e1..8e74521 100755
--- a/website/agenda/planung/studios.cgi
+++ b/website/agenda/planung/studios.cgi
@@ -221,13 +221,7 @@ sub check_params {
     $template = template::check( $config, $params->{template}, 'studios' );
     $checked->{template} = $template;
 
-    #actions
-    my $action = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(save|delete)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of( $params->{action}, ['save', 'delete']);
 
     entry::set_strings( $checked, $params, [
         'name', 'description', 'location', 'stream', 'google_calendar', 'image', 'setImage' ]);
diff --git a/website/agenda/planung/user-settings.cgi b/website/agenda/planung/user-settings.cgi
index 76c6552..f1eca32 100755
--- a/website/agenda/planung/user-settings.cgi
+++ b/website/agenda/planung/user-settings.cgi
@@ -10,6 +10,7 @@ use config();
 use log();
 use template();
 use auth();
+use entry();
 use uac();
 use roles();
 use project();
@@ -248,12 +249,7 @@ sub check_params {
         }
     }
 
-    #actions
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(save|updateDefaultProjectStudio)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of( $params->{action}, ['save', 'updateDefaultProjectStudio']);
     return $checked;
 }
 
diff --git a/website/agenda/planung/user-stats.cgi b/website/agenda/planung/user-stats.cgi
index 8877a58..24d49ae 100755
--- a/website/agenda/planung/user-stats.cgi
+++ b/website/agenda/planung/user-stats.cgi
@@ -10,6 +10,7 @@ use config();
 use log();
 use template();
 use auth();
+use entry();
 use uac();
 use roles();
 use project();
@@ -117,12 +118,9 @@ sub check_params {
 
     my $checked = {};
 
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(show-user-stats|show-active-users)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of( $params->{action}, 
+        ['show-user-stats', 'show-active-users']
+    );
 
     entry::set_numbers( $checked, $params, [
         'project_id', 'default_studio_id', 'studio_id', 'series_id']);
diff --git a/website/agenda/planung/users.cgi b/website/agenda/planung/users.cgi
index e12fed8..385a4b6 100755
--- a/website/agenda/planung/users.cgi
+++ b/website/agenda/planung/users.cgi
@@ -7,6 +7,7 @@ no warnings 'redefine';
 use Data::Dumper;
 
 use config();
+use entry();
 use log();
 use template();
 use auth();
@@ -407,32 +408,17 @@ sub check_params {
         $checked->{studio_id} = -1;
     }
 
-    for my $param ( 'user_name', 'user_full_name', 'user_email' ) {
-        if ( defined $params->{$param} ) {
-            my $value = $params->{$param};
-            $value =~ s/^\s+//g;
-            $value =~ s/\s+$//g;
-            $checked->{$param} = $value;
-        }
-    }
+    entry::set_strings( $checked, $params, 
+        [ 'user_name', 'user_full_name', 'user_email', 'user_password', 'user_password2' ]
+    );
 
-    for my $param ( 'user_password', 'user_password2' ) {
-        if ( defined $params->{$param} ) {
-            $checked->{$param} = $params->{$param};
-        }
-    }
+    $checked->{action} = entry::element_of( $params->{action}, 
+        ['save', 'assign', 'delete', 'change_password']);
 
-    #actions and roles
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(save|assign|delete|change_password)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-
-        if ( $params->{action} eq 'assign' ) {
-            $checked->{action} = $params->{action};
-            for my $param ( keys %$params ) {
-                $checked->{role_ids}->{$1} = 1 if ( $param =~ /^role_(\d+)$/ );
-            }
+    if ( $params->{action} eq 'assign' ) {
+        $checked->{action} = $params->{action};
+        for my $param ( keys %$params ) {
+            $checked->{role_ids}->{$1} = 1 if ( $param =~ /^role_(\d+)$/ );
         }
     }
 
diff --git a/website/agenda/planung/work-time.cgi b/website/agenda/planung/work-time.cgi
index 646ef06..820a8ab 100755
--- a/website/agenda/planung/work-time.cgi
+++ b/website/agenda/planung/work-time.cgi
@@ -8,6 +8,7 @@ use Data::Dumper;
 use URI::Escape();
 use params();
 use config();
+use entry();
 use log();
 use template();
 use auth();
@@ -264,13 +265,9 @@ sub check_params {
 
     my $checked = {};
 
-    #actions and roles
-    $checked->{action} = '';
-    if ( defined $params->{action} ) {
-        if ( $params->{action} =~ /^(show|save_schedule|delete_schedule)$/ ) {
-            $checked->{action} = $params->{action};
-        }
-    }
+    $checked->{action} = entry::element_of( $params->{action}, 
+        ['show', 'save_schedule', 'delete_schedule']
+    );
 
     $checked->{exclude} = 0;
     entry::set_numbers( $checked, $params, [