drupal_form_submit() updates rather than inserts nodes when called multiple times

Please read http://drupal.org/node/45111, this is not critical.

Note sure if drupal_form_submit() counts as the official function for creating nodes :)

Anything that destroys data is critical in my book. I'm going to at least mark it 'major'. Saying "Don't use drupal_form_submit()" is not really a solution. Either the function should work correctly or it should be removed.

Shouldn't you just be using node_save()?

If you need sample code, see DrupalWebTestCase::drupalCreateNode().

I think this is the proper behavior when submitting a form --- we don't want to accidentally create two nodes if a user accidentally clicks the submit button twice.

I think there's ideally two different methodologies at work: validating the "I have no idea how your site works" end-user and validating the "pff, data constraints? yawn!" programmer. If I, as a programmer, want to submit a node with 6000 words in it, I should be able to - but I may not want my end-users doing the same thing. One is the front entrance, via interactive forms (which can do the sort of call and response validation necessary for an individual node submission), and the other is the back entrance, via node_save(), which assumes that if you're at this low of a level, You Know What You're Doing and You Might Want To Do It Two Thousand Times. As another example, If I prevent a form from showing a field to an end-user, I DO NOT want this field to be inaccessible via node_save() (which would be in contest if validation and "all the things forms do" happened at the node_save() level).

Roughly, it breaks down to: drupal_form_submit() assumes bad data is coming in, and node_save() assumes good data is coming in.
You, as the direct caller of node_save(), assert that what you're passing is good data (just like every other function you might call).

Your code will work fine if you remember to reset all of $form_state in each form submit process. That is, you'll need a line like $form_state = array();.

drupal_form_submit() alters the $form_state variable. When you resubmit the form without clearing what it returned, it's not surprising that the behavior is not what you would expect.

Don't forget to check for errors with form_get_error().

If this is not the best way to create a new node, then why does the Services module use this?

function _node_resource_create($node) {
  // Adds backwards compatability with regression fixed in #1083242
  $node = _services_arg_value($node, 'node');

  if (!isset($node['name'])) {
    // Assign username to the node from $user created at auth step.
    global $user;
    $node['name'] = $user->name;
  }

  // Validate the node. If there is validation error Exception will be thrown
  // so code below won't be executed.
  _node_resource_validate_type($node);

  // Load the required includes for drupal_execute
  module_load_include('inc', 'node', 'node.pages');

  $node_type = $node['type'];

  // Setup form_state
  $form_state = array();
  $form_state['values'] = $node;
  $form_state['values']['op'] = variable_get('services_node_save_button_' . $node_type . '_resource_create', t('Save'));
  file_put_contents('/tmp/node.txt', print_r($node,true));
  drupal_form_submit($node_type . '_node_form', $form_state, (object)$node);

  if ($errors = form_get_errors()) {
    return services_error(implode(" ", $errors), 406, array('form_errors' => $errors));
  }
  // Fetch $nid out of $form_state
  $nid = $form_state['nid'];
  // Only add the URI for servers that support it.
  $node = array('nid' => $nid);
  if ($uri = services_resource_uri(array('node', $nid))) {
    $node['uri'] = $uri;
  }
  return $node;
}

I have similar issue when using drupal_form_submit in services when i create multiple node with files attached. The first node can be saved correctly. For the second node and latter node in the for loop, the node array is look fine and attached with new saved fid for new file until drupal_process_form's form_builder.
After drupal_process_form's form_builder, you fid is overridden with previous old fid (the first node's fid). It cause all latter node pointing to the same fid.

i tried set form_state['no_cache'] = true, but still not work.

Thanks,