Using Drupal's node form in a new page - drupal

Question

In a custom module I want to have a page defined in hook_menu, that shows the add form for a specific content type, with some modifications to the form.
So far it's working, and even saving the new node, but only with the default values I'm setting in the code, i.e. it's not picking up anything the user types into the form. I checked and $form_state['input'] contains the inputted values, but $form_state['values'] doesn't, so the new node gets saved wrong.
Here's the relevant code:
function mymodule_menu() {
return array(
'admin/content/myadd/%' => array(
'title' => 'my custom add page',
'page callback' => 'mymodule_node_add',
'page arguments' => array(3),
'access callback' => TRUE,
'type' => MENU_CALLBACK,
),
);
}
function mymodule_node_add() {
module_load_include('inc', 'node', 'node.pages');
//I'm doing a print here instead of returning because I'm calling this page
//in an AJAX popup, so I don't want the whole page to output, only the form.
print render(drupal_get_form('mymodule_node_add_form'));
}
function mymodule_node_add_form($form, &$form_state) {
if (!isset($form_state['node']) {
global $user;
$node = (object) array(
'uid' => $user->uid,
'type' => 'mycontenttype',
'language' => LANGUAGE_NONE,
);
//this is setting a default value
$node->myfield = array(LANGUAGE_NONE => array(array('value' => arg(3))));
$form_state['build_info']['args'] = array($node);
$form = drupal_build_form('mycontenttype_node_form', $form_state);
$form['actions']['submit']['#submit'][0] = 'mymodule_node_add_form_submit';
//there's a lot more customization of the form here, like adding fields, etc.
}
return $form;
}
function mymodule_node_add_form_submit($form, &$form_state) {
//here's where $form_state['input'] is correct but $form_state['values'] isn't.
$node = node_form_submit_build_node($form, $form_state);
node_save($node);
$form_state['values']['nid'] = $node->nid;
$form_state['nid'] = $node->nid;
$form_state['redirect'] = 'some/other/page';
}
So, am I doing something wrong here? Should I be concerned about form ids being wrong? (my form's id is mymodule_node_add_form, but the actual form might output mycontenttype_node_form), would this affect me?

Answer 1

You want hook_form_alter() (see api.drupal.org). I would try to use the existing content type's form and simply alter it with hook_form_alter(). I would also try to first get it working as a standard, non-AJAX page, so you can get all the advantages of dpm() and other debugging techniques. When you have it down solid, then modify it to take advantage of the AJAX techniques.
mymodule_form_alter(&$form, &$form_state, $form_id) {
// use this with your devel module turned on to verify
// your $form_id and contents of all forms that load on a given page
dpm($form);
// once you verify your $form_id, you can begin accessing your form and altering it
switch( $form_id ) {
case 'my_target_form_id' :
// this part is just pseudocode, I haven't memorized the $form structure,
// you can get it from your dpm().
if( $form['node']->type == 'my_target_content_type' ) {
$form['actions']['submit']['#submit'][0] = 'mymodule_node_add_form_submit';
}
break;
}
}