I want to set a unique 7-digit code to a custom content type and display it in a disabled textfield when a node is created. I created a CCK textfield and set it to disabled in hook_form_alter, great.

I think that a good way to make this unique ID is just to use the node id and fill it out to the required length (eg. 0000012). It doesn't look like $nid is available at the node/add form though. How can I set this ID field to default to the $nid? Can I access the hook_form_alter() as the content is created (on form submission)?

3 Answers 3


Implement a field in PHP.

It can keep its own serial counter in a variable, and auto-fill itself with that. You can create formatters for all the different use cases yourself.

Field example code here: http://drupal.org/project/examples

Also I made a UUID field you could hack on: http://drupal.org/sandbox/Mile23/1326218


You're right, the nid is not available at this point, it's assigned only after the the node is saved.

The easiest solution is most probably to use hook_node_insert and resave the node after having added the value to the field you have created.


Looking at the code of node_save(), which the function used to save a node, the hooks that are invoked after drupal_write_record(), which is the function used to set the node ID, are the following ones (when the node is created):

// Call the node specific callback (if any). This can be
// node_invoke($node, 'insert') or
// node_invoke($node, 'update').
node_invoke($node, $op);

// Save fields.
$function = "field_attach_$op";
$function('node', $node);

module_invoke_all('node_' . $op, $node);
module_invoke_all('entity_' . $op, $node, 'node');


Can I access the hook_form_alter() as the content is created (on form submission)?

hook_form_alter() is invoked for a node edit form whenever the node is being created, or the node is being updated. You can add a custom submission handler from hook_form_alter(), which then is able to alter the node being saved.
The hooks I have reported should be sufficient for what you want to do, though.

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