Form element #default_value and AJAX

Question

I can't get a form to display a (default?) value after an AJAX call. I am using the following code:

function foo_form ($form, &$form_state, $foo) {

  $form['#prefix'] = '<div id="foo-form-wrapper">';
  $form['#suffix'] = '</div>';

  $form['copy'] = array(
    '#type' => 'submit',
    '#value' => t('Copy foo'),
    '#limit_validation_errors' => array(),
    // #submit is required to use #limit_validation_errors
    '#submit' => array('foo_form_submit'),
    '#ajax' => array(
      'wrapper' => 'foo-form-wrapper',
      'callback' => 'foo_form_callback',
    ),
  );

  $form['description'] = array(
    '#type' => 'textarea',
    '#title' => t('Short description'),
    '#required' => TRUE,
    '#maxlength' => 255,
    '#default_value' => $foo->description,
  );

  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Save'),
  );

  return $form;
}

function foo_form_callback($form, $form_state) {
  return $form;
}

function foo_form_submit ($form, &$form_state) {
  if (!isset($form_state['triggering_element']['#ajax'])) {
    $foo = (object)$form_state['values'];

    entity_get_controller('foo')->save($foo);

    $form_state['redirect'] = 'admin/foo';
    return;
  } else {
    form_set_value($form['description'], 'description text', $form_state);
    $form_state['rebuild'] = true;
  }
}

As I understand it, the form should automatically try to display the value if it is set in $form_state. When the callback is executed and the form is built, $form_state['values']['description'] is the value set in foo_form_submit. However, nothing is being displayed.

Answer 1

I've experienced similar problems especially with textfields, checkboxes and radios. The solution I found (and I can't guarantee is the "correct" solution) is to change the $form_state['input'][VARIABLE] field. Do this in the validation function:

function foo_form_validate ($form, &$form_state) {
  // this will take a entered value from one element and make it display in another
  $form_state['input']['some_value_to_change'] = $form_state['values']['another_element'];
}

Answer 2

I know this is late, but for people like me who are still experiencing similar problems with ajax and forms in Drupal, here's how I fixed this. In your ajax callback function, instead of returning just the render array, you need to call the form_builder() function and return its result. Eg., my code goes like this:

function inventory_purchase_item_add_ajax(&$form, &$form_state) {
    //...

    unset($form_state['input']['line']);
    unset($form_state['values']['line']);

    //Update the form's lines array
    $lines = update_inventory_purchase_form_lines($form_state['node']->line, $purchase_item_count);
    $form['vtab1']['purchase']['items_wrapper']['line'] = $lines;
    return form_builder($form['#id'], $lines, $form_state);
}

Answer 3

this bug even exists in drupal 8 and is presented HERE.

simplest simple solution is to remove input value of form element in form builder function before creating that element:

unset($form_state['input']['description']);
$form['description'] = array(
    '#type' => 'textarea',
    '#title' => t('Short description'),
    '#required' => TRUE,
    '#maxlength' => 255,
    '#default_value' => $foo->description,
 );

Another solution:

in some cases where there is no java script event handler attached to that element you can have different name for element so input doesn't come in the way, example:

$name='description_'.rand();
$form[$name] = array(
    '#type' => 'textarea',
    '#title' => t('Short description'),
    '#required' => TRUE,
    '#maxlength' => 255,
    '#default_value' => $foo->description,
 );

and save the name in $form for later use (in validation,submittion,...):

$form['a_unique_name']=$name;

Answer 4

thanks, this code works for me, the input method works for me ...

if (isset($form_state['values']['task-name'])) {
  $form_state['input']['task-description'] = show_task_description($form_state['values']['task-name']);
}