diff --git a/lib/outputcomponents.php b/lib/outputcomponents.php
index 4cbd05cde53..3ffed7cbd65 100644
--- a/lib/outputcomponents.php
+++ b/lib/outputcomponents.php
@@ -177,9 +177,10 @@ class user_picture implements renderable {
      * @param string $tableprefix name of database table prefix in query
      * @param array $extrafields extra fields to be included in result (do not include TEXT columns because it would break SELECT DISTINCT in MSSQL and ORACLE)
      * @param string $idalias alias of id field
+     * @param string $fieldprefix prefix to add to all columns in their aliases, does not apply to 'id'
      * @return string
      */
-    public static function fields($tableprefix = '', array $extrafields = NULL, $idalias = 'id') {
+    public static function fields($tableprefix = '', array $extrafields = NULL, $idalias = 'id', $fieldprefix = '') {
         if (!$tableprefix and !$extrafields and !$idalias) {
             return implode(',', self::$fields);
         }
@@ -191,7 +192,11 @@ class user_picture implements renderable {
             if ($field === 'id' and $idalias and $idalias !== 'id') {
                 $fields[$field] = "$tableprefix$field AS $idalias";
             } else {
-                $fields[$field] = $tableprefix.$field;
+                if ($fieldprefix and $field !== 'id') {
+                    $fields[$field] = "$tableprefix$field AS $fieldprefix$field";
+                } else {
+                    $fields[$field] = "$tableprefix$field";
+                }
             }
         }
         // add extra fields if not already there
@@ -200,13 +205,60 @@ class user_picture implements renderable {
                 if ($e === 'id' or isset($fields[$e])) {
                     continue;
                 }
-                $fields[$e] = $tableprefix.$e;
+                if ($fieldprefix) {
+                    $fields[$e] = "$tableprefix$e AS $fieldprefix$e";
+                } else {
+                    $fields[$e] = "$tableprefix$e";
+                }
             }
         }
         return implode(',', $fields);
     }
-}
 
+    /**
+     * Extract the aliased user fields from a given record
+     *
+     * Given a record that was previously obtained using {@link self::fields()} with aliases,
+     * this method extracts user related unaliased fields.
+     *
+     * @param stdClass $record containing user picture fields
+     * @param array $extrafields extra fields included in the $record
+     * @param string $idalias alias of the id field
+     * @param string $fieldprefix prefix added to all columns in their aliases, does not apply to 'id'
+     * @return stdClass object with unaliased user fields
+     */
+    public static function unalias(stdClass $record, array $extrafields=null, $idalias='id', $fieldprefix='') {
+
+        if (empty($idalias)) {
+            $idalias = 'id';
+        }
+
+        $return = new stdClass();
+
+        foreach (self::$fields as $field) {
+            if ($field === 'id') {
+                if (isset($record->{$idalias})) {
+                    $return->id = $record->{$idalias};
+                }
+            } else {
+                if (isset($record->{$fieldprefix.$field})) {
+                    $return->{$field} = $record->{$fieldprefix.$field};
+                }
+            }
+        }
+        // add extra fields if not already there
+        if ($extrafields) {
+            foreach ($extrafields as $e) {
+                if ($e === 'id' or isset($return->{$e})) {
+                    continue;
+                }
+                $return->{$e} = $record->{$fieldprefix.$e};
+            }
+        }
+
+        return $return;
+    }
+}
 
 /**
  * Data structure representing a help icon.
diff --git a/lib/simpletest/testoutputcomponents.php b/lib/simpletest/testoutputcomponents.php
new file mode 100644
index 00000000000..0ca721cc398
--- /dev/null
+++ b/lib/simpletest/testoutputcomponents.php
@@ -0,0 +1,88 @@
+<?php
+
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Unit tests for lib/outputcomponents.php.
+ *
+ * @package   core
+ * @copyright 2011 David Mudrak <david@moodle.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+require_once($CFG->libdir . '/outputcomponents.php');
+
+/**
+ * Unit tests for the user_picture class
+ */
+class user_picture_test extends UnitTestCase {
+
+    public static $includecoverage = array('lib/outputcomponents.php');
+
+    public function test_user_picture_fields_aliasing() {
+        $fields = user_picture::fields();
+        $fields = array_map('trim', explode(',', $fields));
+        $this->assertTrue(in_array('id', $fields));
+
+        $aliased = array();
+        foreach ($fields as $field) {
+            if ($field === 'id') {
+                $aliased['id'] = 'aliasedid';
+            } else {
+                $aliased[$field] = 'prefix'.$field;
+            }
+        }
+
+        $returned = user_picture::fields('', array('custom1', 'id'), 'aliasedid', 'prefix');
+        $returned = array_map('trim', explode(',', $returned));
+        $this->assertEqual(count($returned), count($fields) + 1); // only one extra field added
+
+        foreach ($fields as $field) {
+            if ($field === 'id') {
+                $expected = "id AS aliasedid";
+            } else {
+                $expected = "$field AS prefix$field";
+            }
+            $this->assertTrue(in_array($expected, $returned), "Expected pattern '$expected' not returned");
+        }
+        $this->assertTrue(in_array("custom1 AS prefixcustom1", $returned), "Expected pattern 'custom1 AS prefixcustom1' not returned");
+    }
+
+    public function test_user_picture_fields_unaliasing() {
+        $fields = user_picture::fields();
+        $fields = array_map('trim', explode(',', $fields));
+
+        $fakerecord = new stdClass();
+        $fakerecord->aliasedid = 42;
+        foreach ($fields as $field) {
+            if ($field !== 'id') {
+                $fakerecord->{'prefix'.$field} = "Value of $field";
+            }
+        }
+        $fakerecord->prefixcustom1 = 'Value of custom1';
+
+        $returned = user_picture::unalias($fakerecord, array('custom1'), 'aliasedid', 'prefix');
+
+        $this->assertEqual($returned->id, 42);
+        foreach ($fields as $field) {
+            if ($field !== 'id') {
+                $this->assertEqual($returned->{$field}, "Value of $field");
+            }
+        }
+        $this->assertEqual($returned->custom1, 'Value of custom1');
+    }
+}