diff --git a/modules/rdf/rdf.module b/modules/rdf/rdf.module
index 59dc541f9163a0a20c13a9bc029db0c57f1f05c0..aa7653d182e8715672561be748ac27229c762c23 100644
--- a/modules/rdf/rdf.module
+++ b/modules/rdf/rdf.module
@@ -236,14 +236,13 @@ function rdf_rdfa_attributes($mapping, $data = NULL) {
     // literal text.
     case 'property':
       $attributes['property'] = $mapping['predicates'];
-      if (isset($mapping['callback']) && isset($data)) {
+      // Convert $data to a specific format as per the callback function.
+      if (isset($data) && isset($mapping['callback']) && function_exists($mapping['callback'])) {
         $callback = $mapping['callback'];
-        if (function_exists($callback)) {
-          $attributes['content'] = $callback($data);
-        }
-        if (isset($mapping['datatype'])) {
-          $attributes['datatype'] = $mapping['datatype'];
-        }
+        $attributes['content'] = $callback($data);
+      }
+      if (isset($mapping['datatype'])) {
+        $attributes['datatype'] = $mapping['datatype'];
       }
       break;
   }
diff --git a/modules/rdf/rdf.test b/modules/rdf/rdf.test
index 15c47000bb2cf692b93560d177a12a3e01c47fd4..4b5ea2f5d008d01f563bdb6d8de7094fde551098 100644
--- a/modules/rdf/rdf.test
+++ b/modules/rdf/rdf.test
@@ -35,7 +35,7 @@ class RdfMappingHookTestCase extends DrupalWebTestCase {
       'datatype' => 'xsd:dateTime',
       'callback' => 'date_iso8601',
     ), t('Mapping for created is dc:created with datatype xsd:dateTime and callback date_iso8601.'));
-    $this->assertIdentical($mapping['uid'], array('predicates' => array('sioc:has_creator', 'dc:creator')), t('Mapping for uid is sioc:has_creator and dc:creator.'));
+    $this->assertIdentical($mapping['uid'], array('predicates' => array('sioc:has_creator', 'dc:creator'), 'type' => 'rel'), t('Mapping for uid is sioc:has_creator and dc:creator, and type is rel.'));
 
     $mapping = rdf_mapping_load('test_entity', 'test_bundle_no_mapping');
     $this->assertEqual($mapping, array(), t('Empty array returned when an entity type, bundle pair has no mapping.'));
@@ -60,19 +60,60 @@ class RdfMarkupTestCase extends DrupalWebTestCase {
    * Test rdf_rdfa_attributes().
    */
   function testDrupalRdfaAtributes() {
+    // Same value as the one in the HTML tag (no callback function).
+    $expected_attributes = array(
+      'property' => array('dc:title'),
+    );
+    $mapping = rdf_mapping_load('test_entity', 'test_bundle');
+    $attributes = rdf_rdfa_attributes($mapping['title']);
+    ksort($expected_attributes);
+    ksort($attributes);
+    $this->assertEqual($expected_attributes, $attributes);
+
+    // Value different from the one in the HTML tag (callback function).
     $date = 1252750327;
     $isoDate = date('c', $date);
-
-    $expected_type = 'xsd:dateTime';
-    $expected_property = array('dc:created');
-    $expected_value = $isoDate;
-
+    $expected_attributes = array(
+      'datatype' => 'xsd:dateTime',
+      'property' => array('dc:created'),
+      'content' => $isoDate,
+    );
     $mapping = rdf_mapping_load('test_entity', 'test_bundle');
     $attributes = rdf_rdfa_attributes($mapping['created'], $date);
-
-    $this->assertEqual($expected_type, $attributes['datatype']);
-    $this->assertEqual($expected_property, $attributes['property']);
-    $this->assertEqual($expected_value, $attributes['content']);
+    ksort($expected_attributes);
+    ksort($attributes);
+    $this->assertEqual($expected_attributes, $attributes);
+
+    // Same value as the one in the HTML tag with datatype.
+    $expected_attributes = array(
+      'datatype' => 'foo:bar1type',
+      'property' => array('foo:bar1'),
+    );
+    $mapping = rdf_mapping_load('test_entity', 'test_bundle');
+    $attributes = rdf_rdfa_attributes($mapping['foobar1']);
+    ksort($expected_attributes);
+    ksort($attributes);
+    $this->assertEqual($expected_attributes, $attributes);
+
+    // ObjectProperty mapping (rel).
+    $expected_attributes = array(
+      'rel' => array('sioc:has_creator', 'dc:creator'),
+    );
+    $mapping = rdf_mapping_load('test_entity', 'test_bundle');
+    $attributes = rdf_rdfa_attributes($mapping['foobar_objproperty1']);
+    ksort($expected_attributes);
+    ksort($attributes);
+    $this->assertEqual($expected_attributes, $attributes);
+
+    // Inverse ObjectProperty mapping (rev).
+    $expected_attributes = array(
+      'rev' => array('sioc:reply_of'),
+    );
+    $mapping = rdf_mapping_load('test_entity', 'test_bundle');
+    $attributes = rdf_rdfa_attributes($mapping['foobar_objproperty2']);
+    ksort($expected_attributes);
+    ksort($attributes);
+    $this->assertEqual($expected_attributes, $attributes);
   }
 
 }
diff --git a/modules/rdf/tests/rdf_test.module b/modules/rdf/tests/rdf_test.module
index 46144951b15c16da5b83ff4a88573bd713fa679c..dedd2fd802f330b6d5f78c6353b01fc582159b43 100644
--- a/modules/rdf/tests/rdf_test.module
+++ b/modules/rdf/tests/rdf_test.module
@@ -26,10 +26,23 @@ function rdf_test_rdf_mapping() {
         ),
         'uid' => array(
           'predicates' => array('sioc:has_creator', 'dc:creator'),
+          'type' => 'rel',
         ),
         'foobar' => array(
           'predicates' => array('foo:bar'),
         ),
+        'foobar1' => array(
+          'datatype' => 'foo:bar1type',
+          'predicates' => array('foo:bar1'),
+        ),
+        'foobar_objproperty1' => array(
+          'predicates' => array('sioc:has_creator', 'dc:creator'),
+          'type' => 'rel',
+        ),
+        'foobar_objproperty2' => array(
+          'predicates' => array('sioc:reply_of'),
+          'type' => 'rev',
+        ),
       ),
     ),
     array(