Unique field value for all nodes and content types I have list integer field in 3 content types and each have same possible values (from 1 to 6) and I need to disable user to choose the same number for two nodes, so each node with this field filled in need to be unique.

I found Unique field module but it is not working for me, because I have field in each content type and I need to look at all nodes from all content types and this module is on content type base.

Basic example of what I need:

Field field_1 from content type type_1 have value 5, so field_2 from content type type_2 and field_3 from content type type_3 can't have value 5.

Any idea how to achieve this?
Check out this example 

function custom_node_validate($node, $form) {
  if ($node-&gt;type == 'page') {
    //retrieve the value for your field using Entity API
    $wrapper = entity_metadata_wrapper('node', $node);
    $value = $wrapper-&gt;field_collection-&gt;field_unique-&gt;value();

    //Execute a count query to see if there's other similar values.
    $query = new EntityFieldQuery;
    $query-&gt;entityCondition('entity_type', 'field_collection_item')
      -&gt;fieldCondition('field_unique', 'value', $value)
      -&gt;count();
    $count = $query-&gt;execute();
    if ($count &gt; 1) {
      form_set_error('field_unique', 'Unique field value is already used.');
    }
  }
}