Fill form on ajax callback

Question

Seems to be an extremely simple question. But I can't figure it out. In my module's form I need to load form values depend on the value of certain one and rebuild the form using those.

here is the part of the code (form builder):

$namevalue = isset($form_state['values']['name']) ? $form_state['values']['name'] : "";
$form['name'] = array(
    '#type' => 'textfield',
    '#default_value' => $namevalue
);
$form['load_settings'] = array(
    '#type' => 'button',
    '#value' => t('Load my settings'),
    '#ajax' => array(
        'callback' => 'simplenews_mod_load_subscriptions',
    )
);

Here is the callback:

function simplenews_mod_load_subscriptions( $form, &$form_state){
  $form_state['values']['name'] = "loaded value"; // here will be a function which will get the value form DB
  return $form_state;
}

Nothing changes in the $form_state array. I think I just don't get the basis of ajax in D7 itself... I'd be very appreciated if someone show my the simplest example of how to change a form field value using ajax.

Or alternatively: how do I rebuild form with new values using custom submit callback. Not on validation.

Thank you.

Answer 1

the problem was in the way I pass submit callback. It should be like

'#submit' => array('foo_submit_callback')

ARRAY!

the less visible thing is the most visible one...

Answer 2

You're pretty close...

$form_state['values']['name'] = "loaded value";
return $form_state();

Is wrong for a few reasons:

• Messing with the submitted values ($form_state['values']) directly possibly isn't the best idea; if you need to do it that way, use form_set_value, but even better, stash it somewhere else in $form_state
• $form_state is an array, and can't be invoked as a function. If you look in the logs, your AJAX requests will probably be returning a 500.
• You need to return the element of the form that you want to replace rather than the state; $form_state is by reference so changes you make are persisted to it that way.

You're also missing the wrapper property for the ajax array in the form function, so the system won't be able to manipulate the DOM with the new data.

With those in mind, try something like this for the form function:

$namevalue = isset($form_state['namevalue']) ? $form_state['namevalue'] : "";
$form['name'] = array(
    '#type' => 'textfield',
    '#default_value' => $namevalue,
    '#prefix' => '<div id="name-value-field">',
    '#suffix' => '</div>',
);
$form['load_settings'] = array(
    '#type' => 'button',
    '#value' => t('Load my settings'),
    '#ajax' => array(
        'callback' => 'simplenews_mod_load_subscriptions',
        'wrapper' => 'name-value-field',
    ),
    '#submit' => 'foo_submit_callback',
);

and this for the callback:

$form_state['namevalue'] = "loaded value"; // here will be a function which will get the value form DB
return $form['name'];

and a submit handler for your button to rebuild the form:

function foo_submit_callback($form, &$form_state) {
  $form_state['rebuild'] = TRUE;
}