registerVariable()

void registerVariable(string variableName)

In PHP, a variable is normally only valid within one PHP code element. By using registerVariable(), a variable can be made available for all following PHP code elements.

• variableName
  A string (in quotation marks) with the name of the variable. This cannot be the variable itself (e.g. $item), a string with the name of the variable (e.g. 'item').

In the following example, on page 1, three items are taken from the items in question “AB01”. Following this, the question is asked with these three items – and, on a later page, question “ABO2” is asked with these exact same three items.

// Take three items from question AB01
$itemlist = random_items('AB01', 3);
// Show the respective question
question('AB01', $itemlist);
// Register variable $itemlist
registerVariable('itemlist');

As the variable $itemlist was made available for other pages in the questionnaire, you can just carry on working with $itemlist in another PHP code element.

question('AB02', $itemlist);

On page 4 in the questionnaire, a rather complicated filter is used to determine whether the participant falls into group 1 (prospective clients or clients preparing to do business), or group 2 (current clients). Different questions will be shown later on the in the questionnaire resulting from this classification.

if (
  (value('BB01') == 1) or
  ((value('BB02') < 3) and (value('BB04') == 2)
) {
  $group = 1;
} else {
  $group = 2;
}
registerVariable('group');

The variable $group can also be used later on in the questionnaire.

if ($group == 1) {
  question('BX01');
} else {
  question('BX02');
}

if ($group == 1) {
  question('BX04', '1-3,5,6');
} else {
  question('BX04', '1-5,7,9');
}

Tip: As the group will also be important in the analysis, the use of put() and, on later pages, value() would arguably be more effective here.

4 questions (“AB01” to “AB04”) are displayed with their associated text elements (“text1” to “text4) – but in random order. Therefore, an array is shuffled on page 1 of the questionnaire and made available for the following pages with registerVariable(). For further details, please see chapter Rotation.

$questions = array(
  array('AB01', 'text1'),
  array('AB02', 'text2'),
  array('AB03', 'text3'),
  array('AB04', 'text4')
);
shuffle($questions);
registerVariable('questions');

On the following four pages, each question and text element, which can be found in the corresponding position in the array, is displayed.

text($questions[0][1]);
question($questions[0][0]);

text($questions[1][1]);
question($questions[1][0]);

text($questions[2][1]);
question($questions[2][0]);

text($questions[3][1]);
question($questions[3][0]);