Error: Argument 2 passed to drupal_array_get_nested_value() must be of the type array, string given

Question

I'm using Entityform with some custom module for multipage which is based on FGAM.

Recoverable fatal error: Argument 2 passed to drupal_array_get_nested_value() must be of the type array, string given, called in includes/form.inc on line 1200 and defined in drupal_array_get_nested_value() (line 6771 of includes/common.inc).

The website encountered an unexpected error. Please try again later.

Why this happens and how do I fix or debug this kind of error?

Answer 1

The error:

Argument 2 passed to drupal_array_get_nested_value() must be an array, string or null given

means there is a problem with the structure of your form you're trying to submit. So string/NULL were given instead of array for the second parameter.

The function:

&drupal_array_get_nested_value(array &$array, array $parents, &$key_exists = NULL)

retrieves a value from a nested array with variable depth, for example:

$value = drupal_array_get_nested_value($form, $parents);

Here are the example calls from Drupal core (see the 2nd argument):

./common.inc:  drupal_array_get_nested_value($array, $parents, $key_exists);
./form.inc:      $input = drupal_array_get_nested_value($form_state['input'], $element['#parents'], $input_exists);
./form.inc:  $source = drupal_array_get_nested_value($form_state['complete form'], $element['#machine_name']['source'], $key_exists);

If you don't know which field is causing it, the easiest way to find out is by doing this simple hack (which should be reverted after that of course):

function &drupal_array_get_nested_value(array &$array, $parents, &$key_exists = NULL) {
  if (!is_array($parents)) { var_dump($parents, debug_backtrace()); exit; }

Which would display value of $parents which should be an array and the backtrace.

Usually this could happen during the validation and it can caused by invalid #parents or #limit_validation_errors structure of form array.

If there is no any custom coding involved, then it's a bug of the contrib module which cause that (e.g. Conditional Fields, Email Field, Entity Translation, etc.), so it should be reported against the right module.

---

In my specific case, I've to fix #limit_validation_errors by wrapping it into array() where it contained list of $group['children']:

  $form['actions']['continue'] = array(
    '#type' => 'submit',
    '#value' => t('Continue'),
    '#limit_validation_errors' => array($validate_fields),
    '#submit' => array('foo_form_submit'),
    '#validate' => array('foo_form_validate'),
  );