$form_state->setValue() doesn't save value

Question

I have an validate code:

public function validateForm(array &$form, FormStateInterface $form_state) {
    parent::validateForm($form, $form_state);

    $form_state->setValue('my_variable', $form_state->getValue('my_variable') + 1);
    $form_state->setRebuild();
}

And I previously set my_variable to 1 if it's NULL:

public function buildForm(array $form, FormStateInterface $form_state) {

    if($form_state->getValue('my_variable') == NULL){
        $form_state->setValue('my_variable', 1);
    }
...

I use ajax callback for form submission and the validation works fine. After click on submit button I display my_variable and I see 2 (before submission it's 1).

But when I hit the submit button again I see 2 again, instead of 3. Also, when I re-load the page the data is missing (so it's get value 1 again).

How to prevail the value? It looks like I am operating on copy of $form_state instead of reference but I cannot write &$form_state (public function validateForm(array &$form, FormStateInterface &$form_state)) because it gives me an error (as it's not the correct declaration of validateForm method).

Answer 1

The value in the $form_state (actually everything) is lost after the PHP process ends. So there is no way to preserve your my_variable value via the $form_state. Your best option is to store this value in the session I guess.

Example:

  public function validateForm(array &$form, FormStateInterface $form_state) {
    parent::validateForm($form, $form_state);

    $session = \Drupal::request()->getSession();
    $session->set('my_variable', $session->get('my_variable') + 1);
  }

  public function buildForm(array $form, FormStateInterface $form_state) {
    $session = \Drupal::request()->getSession();

    if (empty($session->get('my_variable'))) {
      $session->set('my_variable', 1);
    }
  }

Do note that the data gets lost as soon as the user clears his cookies and/or the sessions gets invalidated. If you need a permanent global storage (for all users) use the State API. For a permanent storage per user use the Database API.

Answer 2

If it is a custom variable, you should use $form_state->set('property_name', 'value') (instead of "$form_state->setValue(...)").

Example:

public function validateForm(array &$form, FormStateInterface $form_state) {
    parent::validateForm($form, $form_state);

    // Update custom variable (in PHP "null + 1" equals one).
    $form_state->set('my_variable', $form_state->get('my_variable') + 1);

    // Below is only required when your "buildForm(...)" depends on the variable.
    $form_state->setRebuild();
}

Answer 3

Just to add if you'd like to actually save a form value. I do the following when using webform, I imagine it's easily modified for a usual form.

$form['elements']['form_element']['#default_value'] = 'my_value'

Answer 4

You can use

$form_state->setValue('VALUE_NAME', VALUE_PASSING);

Like -

public function validateForm(array &$form, FormStateInterface $form_state) {
    parent::validateForm($form, $form_state);
    $form_state->setValue('csvupload', $file->destination);
    $form_state->setValue('fid', $file->fid);
    $form_state->setRebuild();
}