How do I add validation in the node processor before creating a node? I'm using Feeds import module, after importing CSV file, if a row doesn't match content type validation the feeds import saves that node with empty space in that field. 

Question:
Now i want FeedsNodeProcessor to validate the node, and if there is a empty space it should throw error for that node or should not create node for that row.

Example:
If i have 40 rows in an excel and 39 rows satisfies the conditions of content type and only 1 row doesn't then it has to like this,
39 nodes created.

Updated:
i have added hook_feeds_prevalidate() in my hook_form_alter module.

 function tracker_custom_form_alter(&amp;$form, &amp;$form_state, $form_id) {
   if($form_id == 'orientation_node_form'){
      $form['#validate'][] = 'validate_orientation';
}
}
function validate_orientation($form,&amp;$form_state)
{
....
}
function tracker_custom_feeds_prevalidate($source, &amp;$entity, &amp;$item, $entity_id) {
//      dpm($entity-&gt;feeds_item-&gt;id); - its not printing anything.
//      dpm($item); - its not printing anything.
  if ($entity-&gt;feeds_item-&gt;id == 'bulk_upload') {
     if (empty($item['Billing Type'])) {
         $entity-&gt;feeds_item-&gt;skip = TRUE;
         drupal_set_message('ksdhbf');
   }
 }
}
You can add this functionality in a custom module. But you'll have to add the logic that you have in your node's validation here.

/*
 * Implements hook_feeds_prevalidate()
 */
function mymodule_feeds_prevalidate($source, &amp;$entity, &amp;$item, $entity_id) {
  // the $item contains your csv files column values
  if ($entity-&gt;feeds_item-&gt;id == 'import_name') { // check the feed import ID
    if ($item['some column'] != 'something') { // validate column value
      $entity-&gt;feeds_item-&gt;skip = TRUE; // skips this row from importing
    }
  }
}


Important: I think you'll need 7.x-2.x-dev in order for this hook to work, I'm using it. This is a new hook and I think it has not been added to 7.x-2.0-beta4 yet.