Accessing Form Values Inside submitForm()for Drupal 8 , 9 , 10 , and 11

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8.x , 9.x , 10.x , 11.x

By the time submitForm() runs, every value the user typed is already sitting inside $form_state — Drupal collected it all during the request. This lesson is about the one method you'll use constantly to get that data back out: $form_state->getValue(), plus its variations for nested and multi-value fields.

What you'll learn in this lesson

  • The basic form of getValue() for a top-level field
  • How to read a value nested inside a fieldset or container
  • The difference between getValue() and getValues()

Reading a simple field

$title = $form_state->getValue('title');

The string you pass matches the form element's array key — if you built the field as $form['title'] = [...], you read it back with getValue('title'). This is true no matter what #type the element was; text fields, selects, checkboxes, and dates all come back through the same method.

Reading a nested value

$email = $form_state->getValue(['contact_details', 'email']);

If a field lives inside a fieldset or container — say $form['contact_details']['email'] — pass an array of keys describing the path, from outermost to innermost, instead of a single string. This only works correctly if $form['#tree'] = TRUE; was set when the form was built; without it, Drupal flattens nested values to the top level and the array-path lookup won't find anything.

Getting everything at once

$all_values = $form_state->getValues();

Note the plural. getValues() (no arguments) returns the entire submitted values array in one call — useful when you're about to pass the whole thing to something like an entity's set() calls in a loop, rather than pulling out fields one at a time.

Gotcha: a checkbox's unchecked value is the string '0', not PHP false or null. If you write if ($form_state->getValue('agree')) {...} that still works correctly in PHP (since '0' is falsy), but a strict comparison like === FALSE will silently never match. Use loose comparison or explicitly check == '0'/== '1' for checkbox values.

Quick check: a form has a date field nested inside a fieldset called event_details, and the form set #tree = TRUE. What's the correct call to read it? $form_state->getValue(['event_details', 'date']) — an array path matching the nesting, only reliable because #tree was set.

Key takeaways

  • $form_state->getValue('key') reads one top-level field by its array key.
  • $form_state->getValue(['parent', 'child']) reads a nested field — only reliable when the form set #tree = TRUE.
  • $form_state->getValues() (plural, no arguments) returns every submitted value at once.
  • A checkbox's unchecked value is the string '0' — avoid strict boolean comparisons against it.

Coming up next

Once you've read the submitted values, the next natural step is sending the user somewhere useful. The next lesson covers setRedirect() — controlling exactly where a visitor lands after a successful submission.