Index: openacs-4/packages/acs-tcl/tcl/json-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/json-procs.tcl,v
diff -u -N -r1.4 -r1.5
--- openacs-4/packages/acs-tcl/tcl/json-procs.tcl	20 Aug 2011 20:21:57 -0000	1.4
+++ openacs-4/packages/acs-tcl/tcl/json-procs.tcl	22 Aug 2011 23:46:39 -0000	1.5
@@ -452,6 +452,27 @@
     }
 }
 
+ad_proc util::json::sql_values_to_json_values {row} {
+
+    Converts empty values to "null", consistent with how oracle, mysql, and
+    the nspostgres bindvar hack treats them.
+
+    @param row A row (list) returned by a sql SELECT.
+
+    @return A new list with empty strings converted to null.
+
+} {
+    set new_row {}
+    foreach value $row {
+        if { $value == "" } {
+            lappend new_row null
+        } else {
+            lappend new_row $value
+        }
+    }
+    return $new_row
+}
+
 ad_proc util::json::array::create {values} {
 
     Construct a JSON object with the given values list
Index: openacs-4/packages/scorm-player/tcl/rte-api-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/scorm-player/tcl/rte-api-procs.tcl,v
diff -u -N -r1.3 -r1.4
--- openacs-4/packages/scorm-player/tcl/rte-api-procs.tcl	8 Jul 2010 01:14:22 -0000	1.3
+++ openacs-4/packages/scorm-player/tcl/rte-api-procs.tcl	22 Aug 2011 23:46:40 -0000	1.4
@@ -76,7 +76,7 @@
 } {
     if { [db_0or1row get_suspend_data {}] } {
         db_dml delete_suspend_data {}
-        return $data
+        return [util::json::sql_values_to_json_values $data]
     }
     return
 }
@@ -202,6 +202,10 @@
 
         set attribute_names {}
 
+        # list of modifiers for the attributes.
+
+        set attribute_modifiers {}
+
         # select_attributes is the list of munged attribute names to use in the rowset
         # descriptor for the query.
 
@@ -212,8 +216,9 @@
         # ignored for cp_package, which is very much a special case.
 
         foreach attribute $attribute_list {
-            foreach {name dummy} $attribute {}
+            foreach {name modifier} $attribute {}
             lappend attribute_names $name
+            lappend attribute_modifiers $modifier
             lappend select_attributes cmi_${table}.[scorm_core::db_name -name $name]
         }
         lappend schema $table [util::json::array::create $attribute_names]
@@ -222,6 +227,19 @@
         lappend data $table
         set rows {}
         foreach row $rowset {
+            for { set i 0} { $i < [llength $row] } { incr i } {
+                switch [lindex $attribute_modifiers $i] {        
+                    INTERVAL {
+                        set row [lreplace $row $i $i \
+                            [scorm_player::seconds_to_interval -timestamp [lindex $row $i]]]
+                    }
+                    default {
+                        if { [lindex $row $i] == "" } {
+                            set row [lreplace $row $i $i null]
+                        }
+                    }
+                }
+            }
             lappend rows [util::json::array::create $row]
         }
         lappend data [util::json::array::create $rows]
Index: openacs-4/packages/scorm-player/tcl/scorm-player-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/scorm-player/tcl/scorm-player-procs.tcl,v
diff -u -N -r1.4 -r1.5
--- openacs-4/packages/scorm-player/tcl/scorm-player-procs.tcl	9 Jul 2010 18:44:39 -0000	1.4
+++ openacs-4/packages/scorm-player/tcl/scorm-player-procs.tcl	22 Aug 2011 23:46:40 -0000	1.5
@@ -189,3 +189,20 @@
     return $seconds
 }
 
+ad_proc scorm_player::seconds_to_interval {
+    -timestamp:required
+} {
+    Convert a database interval into a SCORM 2004 style interval.
+
+    Note: only works for hours, minutes and fractional seconds thus far.
+} {
+    if { $timestamp eq "" } {
+        return null
+    }
+    set splits [split $timestamp :]
+    if { [llength $splits] > 3 } {
+        return --code error \
+            "scorm_player::seconds_to_interval only handles hours, minutes, seconds"
+    }
+    return "PT[lindex $splits 0]H[lindex $splits 1]M[lindex $splits 2]S"
+}