Got it working. Here's my working code in case anybody is interesting (suggestions on improving it are welcome as I'm a ProcessWire newbie):
$page_id = (int) $input->post->select_product; // page ID
// Set a temporary upload folder where the files are stored during form processing
// RC: precede temp dir with a period to ensure it remains non-web accessible
//$upload_path = $config->paths->assets . "files/.temp/";
$upload_path = "/Applications/MAMP/htdocs/ProcessWire/site/assets/files/.temp/";
// RC: create temp path if it isn't there already
if(!is_dir($upload_path)) {
if(!wireMkdir($upload_path)) throw new WireException("No upload path");
}
// show empty form
if ($page_id) {
$p = $pages->get($page_id);
$template = $p->template->name; // this is the template where we will get the fields from
// make a form
$form = $modules->get('InputfieldForm');
$form->method = 'post';
$form->action = './';
$form->attr("id+name",'aanvraag-form');
// add the page's fields to the form
$fields = $p->fieldgroup;
foreach ($fields as $field) {
$inputfield = $fields->{$field->name}->getInputfield($p);
$form->append($inputfield);
}
// add template name field to the form
$field = $modules->get("InputfieldHidden");
$field->attr('id', 'Inputfield_template_name');
$field->attr('name', 'template_name');
$field->value = $template;
$form->append($field); // append the field
// add select_product to the form
$field = $modules->get("InputfieldHidden");
$field->attr('id', 'select_product');
$field->attr('name', 'select_product');
$field->value = $page_id;
$form->append($field); // append the field
// add a submit button to the form
$submit = $modules->get('InputfieldSubmit');
$submit->name = 'save_new_aanvraag';
$submit->attr("value", "Go");
$form->append($submit);
// only show the form if it was not just submitted/processed
if (!$input->post->save_new_aanvraag)
echo $form->render();
}
// process the form if it was submitted
if ($input->post->save_new_aanvraag) {
// new wire upload
$u = new WireUpload('images');
$u->setMaxFiles(2);
$u->setMaxFileSize(200*1024);
// tell it to rename rather than overwrite existing files
$u->setOverwrite(false);
$u->setDestinationPath($upload_path);
$u->setValidExtensions(array('jpg', 'jpeg', 'gif', 'png'));
// execute upload and check for errors
$files = $u->execute();
if(!$u->getErrors()) {
// now we assume the form has been submitted.
// tell the form to process input from the post vars.
$form->processInput($input->post);
// validation
$email = $form->get("email");
if ($email && (strpos($email->value,'@hotmail') !== FALSE)) {
// attach an error and it will get displayed along the field
$email->error("Sorry we don't accept hotmail addresses for now.");
}
// see if any errors occurred
if (count( $form->getErrors() )) {
// re-render the form, it will include the error messages
echo $form->render();
} else {
// successful form submission
$np = new Page(); // create new page object
$np->template = $form->get("template_name")->value; // set template
$np->parent = $pages->get('/aanvraag/'); // set the parent
$np->of(false); // turn off output formatting before setting values
$np->save();
foreach ($np->fields as $f) {
// do not sanitize or set Image and File fields here, because that will happen at the next step which will break if we do not skip images and files here
if ($f->type == 'FieldtypeImage' || $f->type == 'FieldtypeFile') continue;
echo $inputval = $form->get($f->name)->value;
// sanitize fields
if ($f->type == 'FieldtypePageTitle') {
$sanitizer->text($inputval);
// also set page name based on title
$np->set('name', $sanitizer->pageName($inputval, true));
}
if ($f->type == 'FieldtypeEmail') $sanitizer->email($inputval);
if ($f->type == 'FieldtypeText') $sanitizer->text($inputval);
if ($f->type == 'FieldtypeTextarea') $sanitizer->textarea($inputval);
if ($f->type == 'FieldtypeInteger') $inputval = (int) $inputval;
// attach fields to page
$np->set($f->name, $inputval);
}
// add images upload
foreach($files as $filename) {
$np->images = $upload_path . $filename;
}
$np->save(); //create the page
// remove all tmp files uploaded
foreach($files as $filename) unlink($upload_path . $filename);
echo "<p>Page saved.</p>";
}
}
else {
// remove files
foreach($files as $filename) unlink($upload_path . $filename);
// get the errors
foreach($u->getErrors() as $error) echo "<p class='error'>$error</p>";
}
} else {
//echo $form->render();
}
Marc's post in simple lazy cron from template not working was marked as the answer