php 8.1:TypeError: strlen(): Argument #1 ($string) must be of type string, array given

Please provide steps to reproduce the error and the raw data of the view and content.

The issue occurs when we install the module's latest version in Drupal php 8.1version.

I can confirm this error and the fix (for me at least) was to open the view, edit format settings and assign a start and end date field.
Save, flush cache and all is good.

I can't reproduce this error on my sites.

It could occur in a certain circumstances.

Please provide more details how this happened, which would make way easier for others to do the trouble shooting and understand why it happens.

The raw data of the view output will tell what really cause this issue.

I tracked it down to:
$left_buttons = Xss::filter($options['left_buttons']); and
$right_buttons = Xss::filter($options['right_buttons']);

lines 168 and line 170 in Drupal\fullcalendar_view\FullcalendarViewPreprocess

strlen() does not accept an array, Xss::filter is using a method Unicode::validateUtf8, which is using strlen().

$options['left_buttons'] and $options['right_buttons'] should be a string, right?

Why an array return?

I believe the issue is with $options['right_buttons']. Using xdebug I see the value below at FullcalendarViewPreprocess.php line 170"

$options['right_buttons'] =
array(7)
0:"dayGridMonth"
1:"timeGridWeek"
2:"timeGridDay"
3:"listYear"
agendaWeek:"agendaWeek"
agendaDay:"agendaDay"
listYear:"listYear"

I was able to `drush config:export` and manually update views.view.calendar.yml from:

          right_buttons:
            agendaWeek: agendaWeek
            agendaDay: agendaDay
            listYear: listYear
          default_view: month

to

          left_buttons: 'prev,next today'
          right_buttons: 'dayGridMonth,timeGridWeek,timeGridDay,listYear'
          default_view: dayGridMonth

after importing the config I manually edited and re-saved the settings in the view, cleared the cache and the error resolved.

Once the view setting is saved, following line in the form submit function will convert the array into a string.

$options['right_buttons'] = isset($options['right_buttons']) ? implode(',', array_filter(array_values($options['right_buttons']))) : 'dayGridMonth,timeGridWeek,timeGridDay,listYear';

You can see the above source code at

https://git.drupalcode.org/project/fullcalendar_view/-/blob/5.1.13/src/P...

And also, the following buttons options are not provided by 5.x version.

• agendaWeek
• agendaDay

The options available in 5.x version are:

    $fullcalendar_displays = [
      'dayGridMonth' => $this->t('Month'),
      'timeGridWeek' => $this->t('Week'),
      'timeGridDay' => $this->t('Day'),
      'listYear' => $this->t('List (Year)'),
      'listMonth' => $this->t('List (Month)'),
      'listWeek' => $this->t('List (Week)'),
      'listDay' => $this->t('List (Day)'),
    ];

https://git.drupalcode.org/project/fullcalendar_view/-/blob/5.1.13/src/P...

@David Kopecek, did you upgrade this module from 2.x? If so, as suggested in #6, what you need to do is just to re-save this view again. That is it.

Every time you save the view setting, the option value will be converted into string as explained above.

Other possibility is that you have some out-of-date configuration YML files remained in your configuration export folder. If that is the case, you also need to clean up/ update those YML files as well. Otherwise, once you re-import those out-of-date configuration back to your site, a misconfiguring issue like this one will occure again.

I close it as it is a misconfiguring issue.

As advised in the 'Upgrade path' session in the project page, if you upgrade this module from 2.x, you have to re-configure/re-save the view. And also you can't re-import the configuration exported for 2.x version. It won't work.