Is there a reason why custom field sets cannot be multiple value?

Question

I've added a custom field set to the Participant entity, but I need to it allow for multiple values. I've noticed that the Contact entity has no problem with this, but is there a reason why it doesn't give you this option for other entities?

I've found the cause in this function in the templates/CRM/Custom/Form/Group.tpl file:

  /**
   * Check if this is a contact-related set and show/hide other options accordingly
   */
  function showHideStyle() {
    var
      extend = $(this).val(),
      contactTypes = {/literal}{$contactTypes}{literal},
      showStyle = "{/literal}{$showStyle}{literal}",
      showMultiple = "{/literal}{$showMultiple}{literal}",
      showMaxMultiple = "{/literal}{$showMaxMultiple}{literal}",
      isContact = ($.inArray(extend, contactTypes) >= 0);

    if (isContact) {
      $("tr#style_row, tr#is_multiple_row").show();
      if ($('#is_multiple :checked').length) {
        $("tr#multiple_row").show();
      }
    }
    else {
      $("tr#style_row, tr#is_multiple_row, tr#multiple_row").hide();
    }

    if (showStyle) {
      $("tr#style_row").show();
    }

    if (showMultiple) {
      $("tr#style_row, tr#is_multiple_row").show();
    }

    if (!showMaxMultiple) {
      $("tr#multiple_row").hide();
    }
    else if ($('#is_multiple').prop('checked')) {
      $("tr#multiple_row").show();
    }
  }

Answer 1

The documentation says they are only possible for contact records. See https://docs.civicrm.org/user/en/latest/organising-your-data/creating-custom-fields/#multiple-record-fieldsets. I expect the reason for this is that it would have been a lot more effort to add it for all for other entities. There are some built in ones for contacts so I guess it was easier to extend for contacts. It wasn't there from the start

Answer 2

I found a way to get the Participant entity to accept multiple values.

To recap, I needed a custom field set that contained single value text, note and file fields, but needed to be able to add multiple instances of the set itself to a Participant.

I added the following code to the top of theCRM_Event_Form_Participant::postProcess method, underneath the line $params = $this->controller->exportValues($this->_name);.

// Get CiviCRM's configuration
$config = CRM_Core_Config::singleton();
$uploadDirectory = $config->uploadDir;

// Filter keys that are in the form of custom_[number]_-[number over 1]
$custom_field_keys = preg_grep('/custom_[0-9]+_-[2-9]+/', array_keys($this->_submitValues));
foreach ($custom_field_keys as $key) {

  // Save these additional values in the $params array
  $params[$key] = $this->_submitValues[$key];
}

// Filter out keys that are in the form of custom_[number]_-[number over 1]
$custom_file_keys = preg_grep('/custom_[0-9]+_-[2-9]+/', array_keys($this->_submitFiles));

foreach ($custom_file_keys as $key) {

  // rename the uploaded file with a unique number at the end
  $file = $this->_submitFiles[$key];

  $element = new HTML_QuickForm_file($key);
  $element->_value = $file;

  $newName = CRM_Utils_File::makeFileName($file['name']);
  $status = $element->moveUploadedFile($uploadDirectory, $newName);
  if (!$status) {
    CRM_Core_Error::statusBounce(ts('We could not move the uploaded file %1 to the upload directory %2. Please verify that the \'Temporary Files\' setting points to a valid path which is writable by your web server.', [
      1 => $value['name'],
      2 => $uploadDirectory,
    ]));
  }
  if (!empty($data['values'][$pageName][$uploadName]['name'])) {
    @unlink($uploadDirectory . $data['values'][$pageName][$uploadName]);
  }

  $value = [
    'name' => $uploadDirectory . $newName,
    'type' => $element->_value['type'],
  ];
  //CRM-19460 handle brackets if present in $uploadName, similar things we do it for all other inputs.
  $value = $element->_prepareValue($value, TRUE);
  $params = HTML_QuickForm::arrayMerge($params, $value);
}

It begins by first getting the upload directory path from configuration and then finding all keys in the _submitValues property that are the second value onwards. Adding these values directly to the $params array appears to work with no additional work.

For files, the same beginning is needed where we find file field keys that are the second onwards, then we must create a new file field instance with HTML_QuickForm_file for each one, so we may utilise the HTML_QuickForm_file::moveUploadedFile() method. If the file is moved successfully, we prepare the new file values and merge them into the $params array.