Issue #2278583 by nlisgo, Berdir, joshi.rohit100 | Fabianx: Fixed field_has_data looks at current data instead of revisioning data: this can lead to data loss.

CHANGELOG.txt

@@ -1,6 +1,9 @@
 
 Drupal 7.33, xxxx-xx-xx (development version)
 -----------------------
+- Fixed a bug in which field_has_data() did not return TRUE for fields that
+  only had data in older entity revisions, leading to loss of the field's data
+  when the field configuration was edited.
 - Fixed a bug which caused the Ajax progress throbber to appear misaligned in
   many situatons (minor styling change).
 - Prevented the Bartik theme from lower-casing the "Permalink" link on

modules/field/field.module

@@ -936,14 +936,17 @@ function field_get_items($entity_type, $entity, $field_name, $langcode = NULL) {
  */
 function field_has_data($field) {
   $query = new EntityFieldQuery();
-  return (bool) $query
-    ->fieldCondition($field)
+  $query = $query->fieldCondition($field)
     ->range(0, 1)
     ->count()
     // Neutralize the 'entity_field_access' query tag added by
     // field_sql_storage_field_storage_query(). The result cannot depend on the
     // access grants of the current user.
-    ->addTag('DANGEROUS_ACCESS_CHECK_OPT_OUT')
+    ->addTag('DANGEROUS_ACCESS_CHECK_OPT_OUT');
+
+  return (bool) $query
+    ->execute() || (bool) $query
+    ->age(FIELD_LOAD_REVISION)
     ->execute();
 }
 

modules/field/tests/field.test

@@ -484,6 +484,66 @@ class FieldAttachStorageTestCase extends FieldAttachTestCase {
     $this->assertEqual($entity->{$this->field_name}[$langcode], $values, 'Insert: missing field results in default value saved');
   }
 
+  /**
+   * Test field_has_data().
+   */
+  function testFieldHasData() {
+    $entity_type = 'test_entity';
+    $langcode = LANGUAGE_NONE;
+
+    $field_name = 'field_1';
+    $field = array('field_name' => $field_name, 'type' => 'test_field');
+    $field = field_create_field($field);
+
+    $this->assertFalse(field_has_data($field), "No data should be detected.");
+
+    $instance = array(
+      'field_name' => $field_name,
+      'entity_type' => 'test_entity',
+      'bundle' => 'test_bundle'
+    );
+    $instance = field_create_instance($instance);
+    $table = _field_sql_storage_tablename($field);
+    $revision_table = _field_sql_storage_revision_tablename($field);
+
+    $columns = array('entity_type', 'entity_id', 'revision_id', 'delta', 'language', $field_name . '_value');
+
+    $eid = 0;
+
+    // Insert values into the field revision table.
+    $query = db_insert($revision_table)->fields($columns);
+    $query->values(array($entity_type, $eid, 0, 0, $langcode, 1));
+    $query->execute();
+
+    $this->assertTrue(field_has_data($field), "Revision data only should be detected.");
+
+    $field_name = 'field_2';
+    $field = array('field_name' => $field_name, 'type' => 'test_field');
+    $field = field_create_field($field);
+
+    $this->assertFalse(field_has_data($field), "No data should be detected.");
+
+    $instance = array(
+      'field_name' => $field_name,
+      'entity_type' => 'test_entity',
+      'bundle' => 'test_bundle'
+    );
+    $instance = field_create_instance($instance);
+    $table = _field_sql_storage_tablename($field);
+    $revision_table = _field_sql_storage_revision_tablename($field);
+
+    $columns = array('entity_type', 'entity_id', 'revision_id', 'delta', 'language', $field_name . '_value');
+
+    $eid = 1;
+
+    // Insert values into the field table.
+    $query = db_insert($table)->fields($columns);
+    $query->values(array($entity_type, $eid, 0, 0, $langcode, 1));
+    $query->execute();
+
+    $this->assertTrue(field_has_data($field), "Values only in field table should be detected.");
+  }
+
   /**
    * Test field_attach_delete().
    */