webform select options validation unique

Question

I need to prevent two different users from choosing the same option from a webform select options component. In the validation only validation required available, no unique validation.

For example: my select contains the following: 1|1, 2|2, 3|3. AnnonUser1 chooses option 2. AnnonUser2 should be presented with 1|1 and 3|3.

How can I validate unique for this select options component. I tried webform validation, but it does not provide unique validation for select options component as well.

Answer 1

You can use a select list with a pre-loaded option list. In that "preload" callback you can alter available options.

Define a custom option list:

function mymodule_webform_select_options_info() {
  $items = array();

  $items['exclusive'] = array(
    'title' => t('Exclusive options'), 
    'options callback' => 'mymodule_webform_options_exclusive', 
  );

  return $items;
}

This callback is called every time the form is displayed, we can alter options here based on previous submissions:

function mymodule_webform_options_exclusive() {
  $default_options = array("One" => 1, "Two" => 2, "Three" => 3);
  $available_values = mymodule_webform_available_values(5); // nid of the webform

  return array_diff($default_options, $available_values);
}

function mymodule_webform_available_values($nid) {
  $submissions = webform_get_submissions(array("nid" => $nid));

  // get all the options values that were already submitted
  $values = array_values(array_map(function($submission) {
    return $submission->data[1][0]; // 1 == index of the field in the form
  }, $submissions));

  return $values;
}

Two things are hard-coded here: nid of the webform (5 here) and the index of the select widget (1 here). It might be possible to avoid hard-coding stuff, good luck!

Answer 2

You will almost definitely have to write some custom code to do what you are describing. Start by Googling for "drupal webform dynamic select". There are lots articles that should give you an idea where to start.

Answer 3

var option_value_order = {'volvo', 'saab', 'mercedes'};
var option_display_strings = new Array();
option_display_strings['volvo'] = 'Volvo'; 
//...

// Assume each of the selects' ID value is "select_1", "select_2" instead of "1", "2"
function redraw(selectNum) {
    var selectId = "select_" + selectNum;
    var s = document.getElementById(selectId);
    s.options.length = 0; // empty out
    var next = 0;
    for (var i = 0; i < option_value_order.length; i++) { 
        var skip = 0;
        for (var select_index = 0; select_index < selectNum; select_index++) {
            if (document.getElementById("select_"+select_index).selected == i)
                skip = 1;
            if (skip == 0) {
                var o = option_value_order[i];
                s.options[next] = o;
                // Don't recall how to set value different from option display, 
                // using option_display_strings[o] 
                next++;
            }
        }
    }
}

var total_selects = 2;

function change_later_selects(s) {
    var select_num = find_number(s.id); "this returns number 2 for "select_2" - homework
    for (var i = select_num + 1; i <= total_selects; i++) {
        redraw(i);
    }
}

and then the HTML code

<select id="select_2" onchange="change_later_selects(this);">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
</select>