Form Handling and Validation in Oorian

Forms are the backbone of most web applications. Oorian provides a robust, type-safe approach to form handling that leverages Java's strengths while keeping your code clean and maintainable.

Basic Form Structure

@Page("/contact")
public class ContactPage extends HtmlPage implements FormListener
{
    private TextInput nameInput;
    private TextInput emailInput;
    private TextArea messageInput;

    @Override
    protected void createBody(Body body)
    {
        OorianForm form = new OorianForm();
        form.registerListener(this, FormEvent.class);

        nameInput = new TextInput();
        nameInput.setName("name");
        nameInput.setPlaceholder("Your Name");
        form.addElement(createFormGroup("Name", nameInput));

        emailInput = new TextInput();
        emailInput.setName("email");
        emailInput.setPlaceholder("your@email.com");
        form.addElement(createFormGroup("Email", emailInput));

        messageInput = new TextArea();
        messageInput.setName("message");
        messageInput.setRows(5);
        form.addElement(createFormGroup("Message", messageInput));

        Button submit = new Button("Send Message");
        form.addElement(submit);

        body.addElement(form);
    }

    @Override
    public void onEvent(FormEvent event)
    {
        Parameters params = event.getParameters();
        String name = params.getParameterValue("name");
        String email = params.getParameterValue("email");
        String message = params.getParameterValue("message");

        // Process form data
        sendContactEmail(name, email, message);
        showSuccessMessage();
    }
}

Form Validation

Validate on the server side where you have full control:

@Override
public void onEvent(FormEvent event)
{
    Parameters params = event.getParameters();
    List<String> errors = new ArrayList<>();

    String name = params.getParameterValue("name");
    if (name == null || name.trim().isEmpty())
    {
        errors.add("Name is required");
        highlightError(nameInput);
    }

    String email = params.getParameterValue("email");
    if (!isValidEmail(email))
    {
        errors.add("Please enter a valid email address");
        highlightError(emailInput);
    }

    if (!errors.isEmpty())
    {
        showErrors(errors);
        return;
    }

    // Proceed with valid data
    processForm(name, email);
}

private void highlightError(Element input)
{
    input.setBorder("2px solid #dc2626");
}

private void clearError(Element input)
{
    input.setBorder("1px solid #d1d5db");
}

Real-Time Validation

For immediate feedback as users type:

public class ContactPage extends HtmlPage implements FormListener, InputListener
{
    @Override
    protected void createBody(Body body)
    {
        emailInput = new TextInput();
        emailInput.registerListener(this, InputChangeEvent.class);
        // ...
    }

    @Override
    public void onEvent(InputChangeEvent event)
    {
        if (event.getSource() == emailInput)
        {
            String email = emailInput.getValue();
            if (email.length() > 3 && !isValidEmail(email))
            {
                emailError.setText("Invalid email format");
                emailError.setDisplay(Display.BLOCK);
            }
            else
            {
                emailError.setDisplay(Display.NONE);
            }
        }
    }
}

Working with Select Elements

Select countrySelect = new Select();
countrySelect.setName("country");
countrySelect.addOption("", "Select a country");
countrySelect.addOption("us", "United States");
countrySelect.addOption("uk", "United Kingdom");
countrySelect.addOption("ca", "Canada");
countrySelect.setSelectedValue("us");

// Handle selection changes
countrySelect.registerListener(this, InputChangeEvent.class);

Checkbox and Radio Buttons

// Checkbox
Checkbox newsletter = new Checkbox();
newsletter.setName("newsletter");
newsletter.setChecked(true);

// Radio buttons
RadioButton small = new RadioButton();
small.setName("size");
small.setValue("small");

RadioButton medium = new RadioButton();
medium.setName("size");
medium.setValue("medium");
medium.setChecked(true);

RadioButton large = new RadioButton();
large.setName("size");
large.setValue("large");

Form Data to Objects

Map form data to domain objects cleanly:

@Override
public void onEvent(FormEvent event)
{
    Customer customer = extractCustomer(event.getParameters());
    validateAndSave(customer);
}

private Customer extractCustomer(Parameters params)
{
    Customer customer = new Customer();
    customer.setName(params.getParameterValue("name"));
    customer.setEmail(params.getParameterValue("email"));
    customer.setPhone(params.getParameterValue("phone"));
    customer.setNewsletter(
        "on".equals(params.getParameterValue("newsletter"))
    );
    return customer;
}

Conclusion

Form handling in Oorian is straightforward and type-safe. Server-side validation gives you complete control, while real-time validation provides immediate user feedback. The familiar Java patterns make form code easy to write and maintain.