Multivalue AutoComplete for Tapestry

I have been very experimenting with tapestry-jquery plugin and it is great to finally go back to jquery. Not only using jquery is very easy but it also comes with a lot of plugins.

There are some improvements that I think can be added to the tapestry-jquery integration but don’t get time to discuss them in the mailing list.

Recently I wanted to use a multivalue autocomplete something on the lines of https://github.com/argoyle/tapestry-tagselect and found a wonderful plugin http://loopj.com/jquery-tokeninput/

So here is a multi-value auto-complete plugin. Is there anything easier than Tapestry ?

@SupportsInformalParameters
@Import(
        library = "jquery.tokeninput.js",
        stylesheet = "token-input.css"
)
public class AutoComplete extends AbstractField {

    @Parameter(autoconnect = true, required = true)
    private List<Object> values;

    @Parameter(required = true)
    private ValueEncoder encoder;

    @Inject
    private ComponentResources resources;

    @Inject
    private JavaScriptSupport javaScriptSupport;

    @Parameter
    private LabelProvider labelProvider;

    @Inject
    private FieldValidationSupport fieldValidationSupport;

    @Parameter(defaultPrefix = BindingConstants.VALIDATE)
    private FieldValidator<Object> validator;

    @SuppressWarnings({"UnusedDeclaration"})
    LabelProvider defaultLabelProvider() {
        return new LabelProvider() {

            public String getLabel(Object value) {
                return value.toString();
            }
        };
    }

    @Inject
    private Request request;

    @Environmental
    private ValidationTracker tracker;

    @SuppressWarnings({"unchecked"})
    @Override
    protected void processSubmission(String controlName) {
        String parameterValue = request.getParameter(controlName);

        this.tracker.recordInput(this, parameterValue);

        if (values == null) {
            values = new ArrayList<Object>();
        } else {
            values.clear();
        }

        for (String value : TapestryInternalUtils.splitAtCommas(parameterValue)) {
            values.add(encoder.toValue(value));
        }

        putPropertyNameIntoBeanValidationContext("values");

        if (validator != null) {
            try {
                fieldValidationSupport.validate(values, resources, validator);
            } catch (final ValidationException e) {
                this.tracker.recordError(this, e.getMessage());
            }
        }

        removePropertyNameFromBeanValidationContext();
    }

    @BeginRender
    void writeFieldTag(MarkupWriter writer) {
        writer.element("input",
                "type", "text",
                "name", getControlName(),
                "id", getClientId());
    }

    @AfterRender
    void afterRender(MarkupWriter writer) {
        writer.end();

        JSONObject parameters = getInformalParametersAsJSON();

        loadCurrentValues(parameters);

        javaScriptSupport.addScript("$('#%s').tokenInput('%s', %s);",
                getClientId(), getCallbackURL(), parameters
        );
    }

    private JSONObject getInformalParametersAsJSON() {
        JSONObject json = new JSONObject();

        for (String param : resources.getInformalParameterNames()) {
            json.put(param, resources.getInformalParameter(param,
                    String.class));
        }

        return json;
    }

    private void loadCurrentValues(JSONObject parameters) {
        if (values != null) {
            parameters.put("prePopulate", toJSON(values));
        }
    }

    private String getCallbackURL() {
        return resources.createEventLink("provideList").toAbsoluteURI();
    }

    @OnEvent("provideList")
    JSONArray provideCompletion(@RequestParameter("q") String queryParams) {
        CaptureResultCallback<List<?>> callback = new CaptureResultCallback<List<?>>();

        boolean wasTriggered = resources.triggerEvent(
                ExtensionEvents.PROVIDE_COMPLETION,
                new Object[]{queryParams},
                callback);

        if (!wasTriggered) {
            throw new RuntimeException("Event '" + 
                    ExtensionEvents.PROVIDE_COMPLETION "' must be handled"));
        }

        return toJSON(callback.getResult());
    }

    @SuppressWarnings({"unchecked"})
    private JSONArray toJSON(List<?> list) {
        JSONArray array = new JSONArray();
        for (Object value : list) {
            JSONObject params = new JSONObject();
            params.put("id", encoder.toClient(value));
            params.put("name", labelProvider.getLabel(value));
            array.put(params);
        }

        return array;
    }

}

public interface LabelProvider<T> {
    String getLabel(T value);
}

public class ExtensionEvents {
    public static final String PROVIDE_COMPLETION = "provideCompletions";
}

Usage

<html
        xmlns:p='tapestry:parameter'
        xmlns:t='http://tapestry.apache.org/schema/tapestry_5_3.xsd'>

    <t:if test='fruits'>
        ${fruits}
    </t:if>

    <form t:type='Form' t:id='Form' action=''>
        <label t:for='fruit' t:type='Label'/>
        <input type='text' t:encoder='encoder' t:type='xeric/AutoComplete' t:id='fruit'
               t:values='fruits'/>

        <br/>
        <input type='submit' value='submit'/>
    </form>
</html>

public class AutoCompleteDemo {

    @Property
    @Persist
    private List<Fruit> fruits;

    @Inject
    private TypeCoercer typeCoercer;

    @OnEvent(EventConstants.ACTIVATE)
    void activate() {
        if (fruits == null) {
            fruits = new ArrayList<Fruit>();
            fruits.add(Fruit.ORANGE);
            fruits.add(Fruit.APRICOT);
        }
    }

    public ValueEncoder<?> getEncoder() {
        return new EnumValueEncoder<Fruit>(typeCoercer, Fruit.class);
    }

    @OnEvent(ExtensionEvents.PROVIDE_COMPLETION)
    List<Fruit> provideCompletion(String query) {
        List<Fruit> fruits = new ArrayList<Fruit>();

        for (Fruit fruit : Fruit.values()) {
            if (fruit.name().toLowerCase().contains(query)) {
                fruits.add(fruit);
            }
        }

        return fruits;
    }
}

public enum Fruit {
    ORANGE, APPLE, BANANA, MANGO, GRAPES, APRICOT
}

From http://tawus.wordpress.com/2011/12/28/multivalue-autocomplete-for-tapestry/