--- loncom/interface/lonhelper.pm	2003/04/10 18:02:09	1.5
+++ loncom/interface/lonhelper.pm	2003/04/11 17:21:18	1.6
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # .helper XML handler to implement the LON-CAPA helper
 #
-# $Id: lonhelper.pm,v 1.5 2003/04/10 18:02:09 bowersj2 Exp $
+# $Id: lonhelper.pm,v 1.6 2003/04/11 17:21:18 bowersj2 Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -472,11 +472,26 @@ sub preprocess {
     }
 }
 
+# FIXME: Document that all postprocesses must return a true value or
+# the state transition will be overridden
 sub postprocess {
     my $self = shift;
-    
+
+    # Save the state so we can roll it back if we need to.
+    my $originalState = $helper->{STATE};
+    my $everythingSuccessful = 1;
+
     for my $element (@{$self->{ELEMENTS}}) {
-        $element->postprocess();
+        my $result = $element->postprocess();
+        if (!$result) { $everythingSuccessful = 0; }
+    }
+
+    # If not all the postprocesses were successful, override
+    # any state transitions that may have occurred. It is the
+    # responsibility of the states to make sure they have 
+    # error handling in that case.
+    if (!$everythingSuccessful) {
+        $helper->{STATE} = $originalState;
     }
 }
 
@@ -690,6 +705,8 @@ sub postprocess {
     if (defined($self->{NEXTSTATE})) {
         $helper->changeState($self->{NEXTSTATE});
     }
+
+    return 1;
 }
 1;
 
@@ -826,7 +843,7 @@ sub render {
     my $result = '';
 
     if ($self->{'multichoice'}) {
-        $result = <<SCRIPT;
+        $result .= <<SCRIPT;
 <script>
     function checkall(value) {
 	for (i=0; i<document.forms.wizform.elements.length; i++) {
@@ -839,16 +856,16 @@ SCRIPT
 <br />
 <input type="button" onclick="checkall(true)" value="Select All" />
 <input type="button" onclick="checkall(false)" value="Unselect All" />
-<br />
+<br />&nbsp;
 BUTTONS
     }
 
     if (defined $self->{ERROR_MSG}) {
-        $result .= '<font color="#FF0000">' . $self->{ERROR_MSG} . '</font><br /><br />';
+        $result .= '<br /><font color="#FF0000">' . $self->{ERROR_MSG} . '</font><br />';
     }
 
     $result .= $buttons;
-
+    
     $result .= "<table>\n\n";
 
     my $type = "radio";
@@ -878,6 +895,17 @@ sub postprocess {
     my $self = shift;
     my $chosenValue = $ENV{'form.' . $self->{'variable'} . '.forminput'};
 
+    if (!$chosenValue) {
+        $self->{ERROR_MSG} = "You must choose one or more choices to" .
+            " continue.";
+        return 0;
+    }
+
+    if ($self->{'multichoice'}) {
+        $self->process_multiple_choices($self->{'variable'}.'.forminput',
+                                        $self->{'variable'});
+    }
+
     if (defined($self->{NEXTSTATE})) {
         $helper->changeState($self->{NEXTSTATE});
     }
@@ -889,6 +917,7 @@ sub postprocess {
             }
         }
     }
+    return 1;
 }
 1;
 
@@ -1089,7 +1118,7 @@ sub postprocess {
         $checkDate->year + 1900 != $year) {
         $self->{ERROR_MSG} = "Can't use " . $months[$month] . " $day, $year as a "
             . "date because it doesn't exist. Please enter a valid date.";
-        return;
+        return 0;
     }
 
     $helper->{VARS}->{$var} = $chosenDate;
@@ -1097,6 +1126,8 @@ sub postprocess {
     if (defined($self->{NEXTSTATE})) {
         $helper->changeState($self->{NEXTSTATE});
     }
+
+    return 1;
 }
 1;
 
@@ -1304,6 +1335,8 @@ sub postprocess {
     if (defined($self->{NEXTSTATE})) {
         $helper->changeState($self->{NEXTSTATE});
     }
+
+    return 1;
 }
 
 1;
@@ -1434,6 +1467,27 @@ BUTTONS
     return $result;
 }
 
+sub postprocess {
+    my $self = shift;
+
+    my $result = $ENV{'form.' . $self->{'variable'} . '.forminput'};
+    if (!$result) {
+        $self->{ERROR_MSG} = 'You must choose at least one student '.
+            'to continue.';
+        return 0;
+    }
+
+    if ($self->{'multichoice'}) {
+        $self->process_multiple_choices($self->{'variable'}.'.forminput',
+                                        $self->{'variable'});
+    }
+    if (defined($self->{NEXTSTATE})) {
+        $helper->changeState($self->{NEXTSTATE});
+    }
+
+    return 1;
+}
+
 1;
 
 package Apache::lonhelper::files;
@@ -1579,6 +1633,10 @@ BUTTONS
 
     $result .= $buttons;
 
+    if (defined $self->{ERROR_MSG}) {
+        $result .= '<br /><font color="#FF0000">' . $self->{ERROR_MSG} . '</font><br /><br />';
+    }
+
     $result .= '<table border="0" cellpadding="1" cellspacing="1">';
 
     # Keeps track if there are no choices, prints appropriate error
@@ -1621,6 +1679,13 @@ BUTTONS
 
 sub postprocess {
     my $self = shift;
+    my $result = $ENV{'form.' . $self->{'variable'} . '.forminput'};
+    if (!$result) {
+        $self->{ERROR_MSG} = 'You must choose at least one file '.
+            'to continue.';
+        return 0;
+    }
+
     if ($self->{'multichoice'}) {
         $self->process_multiple_choices($self->{'variable'}.'.forminput',
                                         $self->{'variable'});
@@ -1628,6 +1693,8 @@ sub postprocess {
     if (defined($self->{NEXTSTATE})) {
         $helper->changeState($self->{NEXTSTATE});
     }
+
+    return 1;
 }
 
 1;