Creating a custom validator

Add the following code to your theme functions.php file (or create a plugin for it) and customize it to suit. If the given value $value fails your own validation, then set $valid to false and set the error message by calling $element->addError('Your error message');. See the examples below.

Require that the value is equal to a string

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add_filter('quform_element_valid_1_3', function ($valid, $value, Quform_Element_Field $element) {    if ($value != 'Foo') {        $element->addError('The value is not Foo');        $valid = false;
    }
 
    return $valid;
}, 10, 3);

add_filter('quform_element_valid_1_3', function ($valid, $value, Quform_Element_Field $element) {
    if ($value != 'Foo') {
        $element->addError('The value is not Foo');
        $valid = false;
    }

    return $valid;
}, 10, 3);

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function my_custom_validator($valid, $value, Quform_Element_Field $element)
{
    if ($value != 'Foo') {        $element->addError('The value is not Foo');        $valid = false;
    }
 
    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_custom_validator', 10, 3);

function my_custom_validator($valid, $value, Quform_Element_Field $element)
{
    if ($value != 'Foo') {
        $element->addError('The value is not Foo');
        $valid = false;
    }

    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_custom_validator', 10, 3);

Require that the value is greater than a number

Note: you can use the Greater Than validator on the Advanced tab of the element settings for this instead of using a custom validator.

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add_filter('quform_element_valid_1_3', function ($valid, $value, Quform_Element_Field $element) {    if ($value <= 18) {        $element->addError('The value is not greater than 18');        $valid = false;
    }
 
    return $valid;
}, 10, 3);

add_filter('quform_element_valid_1_3', function ($valid, $value, Quform_Element_Field $element) {
    if ($value <= 18) {
        $element->addError('The value is not greater than 18');
        $valid = false;
    }

    return $valid;
}, 10, 3);

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function my_custom_validator($valid, $value, Quform_Element_Field $element)
{
    if ($value <= 18) {        $element->addError('The value is not greater than 18');        $valid = false;
    }
 
    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_custom_validator', 10, 3);

function my_custom_validator($valid, $value, Quform_Element_Field $element)
{
    if ($value <= 18) {
        $element->addError('The value is not greater than 18');
        $valid = false;
    }

    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_custom_validator', 10, 3);

Matching one token from many

Note: you can use the In Array validator on the Advanced tab of the element settings for this instead of using a custom validator.

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add_filter('quform_element_valid_1_3', function ($valid, $value, $element) {    $codes = array('12345', '67890', 'abcde', 'fghijk'); 
    if (!in_array($value, $codes)) {
        $element->addError('Invalid code');        $valid = false;
    }
 
    return $valid;
}, 10, 3);

add_filter('quform_element_valid_1_3', function ($valid, $value, $element) {
    $codes = array('12345', '67890', 'abcde', 'fghijk');

    if (!in_array($value, $codes)) {
        $element->addError('Invalid code');
        $valid = false;
    }

    return $valid;
}, 10, 3);

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function my_custom_validator($valid, $value, $element)
{
    $codes = array('12345', '67890', 'abcde', 'fghijk'); 
    if (!in_array($value, $codes)) {
        $element->addError('Invalid code');        $valid = false;
    }
 
    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_custom_validator', 10, 3);

function my_custom_validator($valid, $value, $element)
{
    $codes = array('12345', '67890', 'abcde', 'fghijk');

    if (!in_array($value, $codes)) {
        $element->addError('Invalid code');
        $valid = false;
    }

    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_custom_validator', 10, 3);

Accessing other form values

Within the validator function you can access the values of other form elements using the code below.

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$form = $element->getForm();
$otherValue = $form->getValue('quform_1_4');

$form = $element->getForm();
$otherValue = $form->getValue('quform_1_4');

• Change 1_4 to the other element unique ID

Multiple custom validators

If you are using the PHP 5.2 code for creating a custom validator, where the validator function has the name my_custom_validator you will run into a problem if you try and use the same code for a second validator because PHP does not allow you to have more than one function with the same name, so if you have more than one custom validator you will need to choose another function name and also change the second parameter to the add_filter function to your new function name. You can simply add a number to the end of the function name to make it different, or you can use a more descriptive name. Below is an example.

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function my_validate_greater_than_18($valid, $value, $element){
    if ($value <= 18) {
        $element->addError('The value is not greater than 18');
        $valid = false;
    }
 
    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_validate_greater_than_18', 10, 3);

function my_validate_greater_than_18($valid, $value, $element)
{
    if ($value <= 18) {
        $element->addError('The value is not greater than 18');
        $valid = false;
    }

    return $valid;
}
add_filter('quform_element_valid_1_3', 'my_validate_greater_than_18', 10, 3);

Notice the highlighted lines, the function name and the second parameter to add_filter have changed to something different from the above examples, allowing more than one custom validator.