How can I know which button was clicked?

Question

I have a form with a "Submit" and a "Cancel" buttons. In hook_submit(), how do I know which button was clicked?

Answer 1

You must use the triggering_element from the $form_state['triggering_element'].

Best practice is to define a #name attribute for your button, so you can have this value in the triggering_element.

For example:

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

If you don't define this attribute triggering_element will hold the button's #value (the text that user can read), but this is discouraged as other modules may change this value or be changed by the localization).

You may use $form_state['clicked_button'] too, but this is deprecated.

You can read more info at the drupal_build_form function documentation page.

Answer 2

$form_state['clicked_button']['#value'] will tell you which button was clicked on the form.

Answer 3

UPDATE 2016 Drupal 8

For those still trying to figure out how to access the triggered event here is the Drupal 8 solution.

$form_state->getTriggeringElement()

This returns the array of the triggering submit element. If you add a markup called #name then you would access it with the following way.

$button_clicked = $form_state->getTriggeringElement()['#name']

The reason behind this change is that FormStateInterface is now a readOnly file in which only classes that extend FormStateInterface can access the variables. So you have to use accessor methods like getTriggeringElement() in order to access the variable.

Answer 4

Compare these values in $form_state I have been doing in Drupal 6 and would be same in Drupal7

if($form_state['values']['ok'] == $form_state]['clicked_button']['#value']){
    //Process if OK is pressed
}else if($form_state['values']['cancel'] == $form_state]['clicked_button']['#value']) {
    //Process if Cancel is pressed
}

Answer 5

Name the buttons with the #name attribute, like this:

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

and then use:

$values = $form_state['input'];
if (isset($values['delete'])) // 'delete' button was pressed.

Answer 6

In Drupal 8.4.4 $form_state->getTriggeringElement()['#name']; gives you the value of op. When you look for that key in the form state's values array, you get the #value key of the button form element-- in other words, the string that the end users sees on the button on the page.

I don't know if $form_state->getValues()['op'] is universal for all forms, but I'm hard-coding it in my module's form.

Answer 7

Drupal 8.6.7

Create button something like below.

$form['my_button'] = [
    '#type' => 'button',
    '#value' => t('Custom Button'),
    '#name' => t('customButton'),
    '#weight' => 0,
    '#attributes' => [
      'class' => ['populate-bib-button', 'btn', 'btn-primary'],
    ],
  ];

In your submit function get button name like below code.

$input = $form_state->getUserInput();
print $input['_triggering_element_name']; // customButton

Comparison can be done like

if ($input['_triggering_element_name'] == 'customButton') {
  // Do something.
}

#Drupal8