Using and, or, xor in #states logicfor Drupal 8 , 9 , 10 , and 11

Having explored various #states functionalities within Drupal's Form API—from setting visibility to dynamically requiring fields—it's time to delve into using logical operators. These operators allow for advanced conditional logic within your forms, aligning form behavior with complex needs and interactions.

Why Use Logical Operators in #states?

Logical operators enable you to define conditions that depend on a combination of multiple inputs. This capability is crucial when form actions rely on a composite of several user interactions, resulting in more nuanced control over form behavior.

• Comprehensive Logic: Encapsulate intricate rules that reflect multi-condition scenarios, enhancing form responsiveness.
• Refined User Experience: Dynamically guide users based on a broader set of inputs, providing path-specific interactions.
• Greater Flexibility: Increase your form's adaptability to complex workflows or intricate decision trees.

Logical Operators: and, or, xor

Let's briefly explain the purpose of each logical operator in #states:

• AND: All conditions must be true for the resultant state to be activated.
• OR: Any one of the conditions must be true to activate the resultant state.
• XOR: Exactly one condition must be true; if more than one is true, the state is not activated.

Example: Using and, or, xor in a Form

Consider a multi-step signup process where specific sections of the form are displayed based on user selections. You'll implement logic that considers combinations like agreement to terms and receipt of promotional information.

function mymodule_signup_form(array &$form, \Drupal\Core\Form\FormStateInterface $form_state) {
 

$form['agree_terms'] = [
    '#type' => 'checkbox',
    '#title' => t('I agree to the terms and conditions'),
];

$form['subscribe_promo'] = [
    '#type' => 'checkbox',
    '#title' => t('Subscribe to promotional newsletters'),
];

$form['bonus_offer'] = [
    '#type' => 'textfield',
    '#title' => t('Get bonus offer'),
    '#states' => [
        'visible' => [
            'and' => [
                ':input[name="agree_terms"]' => ['checked' => TRUE],
                ':input[name="subscribe_promo"]' => ['checked' => TRUE],
            ],
        ],
    ],
];

$form['submit'] = [
    '#type' => 'submit',
    '#value' => t('Complete Signup'),
];

return $form;

Explanation of the Code

Here's how to harness logical operators in #states with the above example:

• The form asks users to agree to terms and subscribe for newsletters with two checkboxes.
• The bonus_offer text field becomes visible only when both the agree_terms and subscribe_promo checkboxes are checked. This uses the 'and' logical operator to ensure all conditions are met.
• This simple setup can be expanded to include 'or' and 'xor' logic, allowing a single checkbox to trigger functionality or logic that requires exclusive conditions.

Advanced Logic with Logical Operators

In complex scenarios, you may need to use and, or, and xor conditions together, tailoring rules that govern sophisticated interactive forms. These operators enhance your ability to define form logic precisely and comprehensively within the Drupal ecosystem.

Conclusion

Incorporating logical operators in your form's #states results in a refined, flexible user experience, accommodating a broad spectrum of user actions and behavioral permutations. Through this advanced logic, forms can dynamically cater to unique user journeys, providing relevant paths and outcomes.