Dynamic Field Addition in Enterprise Forms HST Component at Runtime

/**
 * DynamicFieldsEformComponent to demonstrate how to add an extra field at runtime even if there's no field definition
 * in the associated form document.
 * 
 * <P>
 * An example hst component which adds a runtime field ('State') when the URL has a query parameter, "region=US".
 * </P>
 */
public class DynamicFieldsEformComponent extends FormStoringEformComponent {

    @Override
    protected Form parse(final FormBean bean, final FormContext formContext, final HstRequest request) {
        Form form = FormFieldFactory.createForm(bean, formContext, null, request);

        if (isStateFieldNecessary(request)) {
            final TextField stateField = createStateTextField(form);

            // First, register the field in the form so that the form becomes aware of what to store/retrieve.
            form.registerField(stateField);
            // Second, insert the state field into the specific position of a page in the form
            form.getPages().get(0).addField(3, stateField);
        }

        return form;
    }

    /**
     * Let's suppose this method is reponsible for collection user state information and determine whether
     * an extra field should be shown or not based on the underlyig business logic which might invoke a backend system as well.
     * <P>
     * For simplicity, this method simply determines it based on query string parameter.
     * If there's a query string parameter, "region=US", then it returns true.
     * </P>
     * @param request
     * @return
     */
    private boolean isStateFieldNecessary(final HstRequest request) {
        String region = getPublicRequestParameter(request, "region");
        return (StringUtils.equalsIgnoreCase("US", region));
    }

    /**
     * Creates an extra required field at runtime for 'State' input text field.
     * 
     * @param form
     * @return
     */
    private TextField createStateTextField(final Form form) {
        TextField stateTextField = TextField.builder(form, "state")
                .label("State")
                .length(40)
                .mandatory(true)
                .minLength(1)
                .maxLength(40).build();
        return stateTextField;
    }
}

/**
 * DynamicRegistrationEformComponent to demonstrate how to add extra fields/groups/pages at runtime even if there's no
 * field definition in the associated form document.
 *
 * <P>
 * An example hst component which adds multiple pages, each to enter a person's information when the URL has a
 * query parameter, "people=$number", e.g. "people=3"
 * </P>
 */
public class DynamicRegistrationEformComponent extends FormStoringEformComponent {
    private static Logger log = LoggerFactory.getLogger(DynamicRegistrationEformComponent.class);

    @Override
    protected Form parse(final FormBean bean, final FormContext formContext, final HstRequest request) {
        Form form = super.parse(bean, formContext, request);

        long numberOfPeople = getRegisteringPeople(request);
        if (numberOfPeople > 0) {
            for(int i = 0; i < numberOfPeople; i++) {
                final String name = String.format("person-%d", i + 1);
                final String label = String.format("Person %d", i + 1);
                FieldGroup contactFieldGroup = createContactFieldGroup(form, name, label);
                Page page = new Page(label);
                page.addField(contactFieldGroup);

                form.getPages().add(page);
            }
        }

        return form;
    }

    private long getRegisteringPeople(final HstRequest request) {
        String numberOfPeopleValue = getPublicRequestParameter(request, "people");
        return StringUtils.isNotEmpty(numberOfPeopleValue) ? Long.parseLong(numberOfPeopleValue) : 0;
    }

    private FieldGroup createContactFieldGroup(final Form form, final String name, final String label) {
        FieldGroup fieldGroup = FieldGroup.builder(form, name, name).label(label).build();
        form.registerFieldGroup(fieldGroup);

        String[][] fieldNames = {
                {"name", "Name"},
                {"email", "Email"},
                {"street-addr", "Street Address"},
                {"city", "City"},
                {"postal-code", "Postal code"}
        };

        for(String[] fieldName : fieldNames) {

            TextField field = TextField.builder(form, fieldName[0])
                    .label(fieldName[1])
                    .length(40)
                    .minLength(1)
                    .maxLength(40)
                    .build();
            // Always add new field to the group to set the proper field group prefix before registering to the form.
            fieldGroup.addField(field);
            form.registerField(field);
        }
        DateField dobField = DateField.builder(form, "dob")
                .label("Date of Birth")
                .dateFormat("dd/MM/yyyy")
                .build();
        fieldGroup.addField(2, dobField);
        form.registerField(dobField);

        String[] genderValues = {"male", "female", "other"};
        String[] genderDisplayValues = {"Male", "Female", "Unspecified"};
        AbstractField genderField = RadioGroup.builder(form, "gender", Arrays.asList(genderValues))
                .displayValues(Arrays.asList(genderDisplayValues))
                .label("Gender")
                .hint("Select your gender")
                .build();
        fieldGroup.addField(3, genderField);
        form.registerField(genderField);

        return fieldGroup;
    }
}