--- loncom/metadata_database/LONCAPA/lonmetadata.pm	2004/04/23 20:30:07	1.9
+++ loncom/metadata_database/LONCAPA/lonmetadata.pm	2004/06/11 19:52:12	1.10
@@ -1,6 +1,6 @@
 # The LearningOnline Network with CAPA
 #
-# $Id: lonmetadata.pm,v 1.9 2004/04/23 20:30:07 matthew Exp $
+# $Id: lonmetadata.pm,v 1.10 2004/06/11 19:52:12 matthew Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -285,8 +285,7 @@ sub create_statement_handler {
 sub clear_sth { $sth=undef; $sth_table=undef;}
 
 sub store_metadata {
-    my $dbh = shift();
-    my $tablename = shift();
+    my ($dbh,$tablename,@Metadata)=@_;
     my $errors = '';
     if (! defined($sth) || 
         ( defined($tablename) && ($sth_table ne $tablename)) || 
@@ -294,15 +293,19 @@ sub store_metadata {
         &create_statement_handler($dbh,$tablename);
     }
     my $successcount = 0;
-    while (my $mdata = shift()) {
+    foreach my $mdata (@Metadata) {
         next if (ref($mdata) ne "HASH");
         my @MData;
         foreach my $field (@Metadata_Table_Description) {
-            if (exists($mdata->{$field->{'name'}})) {
-                if ($mdata->{$field->{'name'}} eq 'nan') {
+            my $fname = $field->{'name'};
+            if (exists($mdata->{$fname}) && 
+                defined($mdata->{$fname}) &&
+                $mdata->{$fname} ne '') {
+                if ($mdata->{$fname} eq 'nan' ||
+                    $mdata->{$fname} eq '') {
                     push(@MData,'NULL');
                 } else {
-                    push(@MData,$mdata->{$field->{'name'}});
+                    push(@MData,$mdata->{$fname});
                 }
             } else {
                 push(@MData,undef);
@@ -314,6 +317,7 @@ sub store_metadata {
         } else {
             $errors = join(',',$errors,$sth->errstr);
         }
+        $errors =~ s/^,//;
     }
     if (wantarray()) {
         return ($successcount,$errors);
@@ -342,10 +346,11 @@ The array reference is the same one retu
 ######################################################################
 ######################################################################
 sub lookup_metadata {
-    my ($dbh,$condition,$fetchparameter) = @_;
+    my ($dbh,$condition,$fetchparameter,$tablename) = @_;
+    $tablename = 'metadata' if (! defined($tablename));
     my $error;
     my $returnvalue=[];
-    my $request = 'SELECT * FROM metadata';
+    my $request = 'SELECT * FROM '.$tablename;
     if (defined($condition)) {
         $request .= ' WHERE '.$condition;
     }
@@ -374,13 +379,86 @@ sub lookup_metadata {
 
 =item delete_metadata()
 
-Not implemented yet
+Removes a single metadata record, based on its url.
+
+Inputs: $dbh, the database handler.
+$tablename, the name of the metadata table to remove from. default: 'metadata'
+$url, the url of the resource to remove from the metadata database.
+
+Returns: undef on success, dbh errorstr on failure.
+
+=cut
+
+######################################################################
+######################################################################
+sub delete_metadata {
+    my ($dbh,$tablename,$url) = @_;
+    $tablename = 'metadata' if (! defined($tablename));
+    my $error;
+    my $delete_command = 'DELETE FROM '.$tablename.' WHERE url='.
+        $dbh->quote($url);
+    $dbh->do($delete_command);
+    if ($dbh->err) {
+        $error = $dbh->errstr();
+    }
+    return $error;
+}
+
+######################################################################
+######################################################################
+
+=pod
+
+=item update_metadata
+
+Updates metadata record in mysql database.  It does not matter if the record
+currently exists.  Fields not present in the new metadata will be taken
+from the current record, if it exists.  To delete an entry for a key, set 
+it to "" or undef.
+
+Inputs: 
+$dbh, database handle
+$newmetadata, hash reference containing the new metadata
+$tablename, metadata table name.  Defaults to 'metadata'.
+
+Returns:
+$error on failure.  undef on success.
 
 =cut
 
 ######################################################################
 ######################################################################
-sub delete_metadata {}
+sub update_metadata {
+    my ($dbh,$tablename,$newmetadata)=@_;
+    my $error;
+    $tablename = 'metadata' if (! defined($tablename));
+    if (! exists($newmetadata->{'url'})) {
+        $error = 'Unable to update: no url specified';
+    }
+    return $error if (defined($error));
+    # 
+    # Retrieve current values
+    my $row;
+    ($error,$row) = &lookup_metadata($dbh,
+                                   ' url='.$dbh->quote($newmetadata->{'url'}),
+                                     undef,$tablename);
+    return $error if ($error);
+    my %metadata = &LONCAPA::lonmetadata::metadata_col_to_hash(@{$row->[0]});
+    #
+    # Update metadata values
+    while (my ($key,$value) = each(%$newmetadata)) {
+        $metadata{$key} = $value;
+    }
+    #
+    # Delete old data (deleting a nonexistant record does not produce an error.
+    $error = &delete_metadata($dbh,$tablename,$newmetadata->{'url'});
+    return $error if (defined($error));
+    #
+    # Store updated metadata
+    my $success;
+    ($success,$error) = &store_metadata($dbh,$tablename,\%metadata);
+    return $error;
+}
 
 ######################################################################
 ######################################################################
@@ -719,9 +797,6 @@ sub escape {
     return $str;
 }
 
-
-
-
 1;
 
 __END__;