We usually just style the various Tapestry link components to get buttons
with the desired behavior.
--
Chris
On Wed, Sep 11, 2019 at 1:45 PM Luca Arzeni <l.arz...@iname.com> wrote:
> Hi there,
> I googled a little around, but I was not able to find a tapestry component
> that generates a button.
>
> Here you can find a first attempt to create such component.
> It was shameless copied from the Submit component already present in
> tapestry.
>
> I would be happy if someone more expert than me could revise it and add to
> the core components.
>
> Regards,
> larzeni
>
> package org.apache.tapestry5.corelib.components;
>
> import org.apache.tapestry5.BindingConstants;
> import org.apache.tapestry5.ClientElement;
> import org.apache.tapestry5.ComponentAction;
> import org.apache.tapestry5.ComponentResources;
> import org.apache.tapestry5.EventConstants;
> import org.apache.tapestry5.MarkupWriter;
> import org.apache.tapestry5.TrackableComponentEventCallback;
> import org.apache.tapestry5.annotations.Environmental;
> import org.apache.tapestry5.annotations.Events;
> import org.apache.tapestry5.annotations.Import;
> import org.apache.tapestry5.annotations.Parameter;
> import org.apache.tapestry5.annotations.SupportsInformalParameters;
> import org.apache.tapestry5.corelib.SubmitMode;
> import org.apache.tapestry5.corelib.components.Form;
> import org.apache.tapestry5.corelib.components.Loop;
> import org.apache.tapestry5.internal.util.Holder;
> import org.apache.tapestry5.ioc.annotations.Inject;
> import org.apache.tapestry5.ioc.internal.util.InternalUtils;
> import org.apache.tapestry5.json.JSONArray;
> import org.apache.tapestry5.services.FormSupport;
> import org.apache.tapestry5.services.Heartbeat;
> import org.apache.tapestry5.services.Request;
> import org.apache.tapestry5.services.javascript.JavaScriptSupport;
>
> /**
> * Corresponds to <input type="submit"> or <input
> type="image">, a client-side element that can force the
> * enclosing form to submit. The submit responsible for the form
> submission will post a notification that allows the
> * application to know that it was the responsible entity. The
> notification is named
> * {@linkplain EventConstants#SELECTED selected}, by default, and has no
> context.
> *
> * @tapestrydoc
> */
> @SupportsInformalParameters
> @Events(EventConstants.SELECTED + " by default, may be overridden")
> @Import(module="t5/core/forms")
> public class Html5Button implements ClientElement {
>
> /**
> * If true (the default), then any notification sent by the
> component will be deferred until the end of the form
> * submission (this is usually desirable). In general, this can be
> left as the default except when the Submit
> * component is rendering inside a {@link Loop}, in which case
> defer should be bound to false (otherwise, the
> * event context will always be the final value of the Loop).
> */
> @Parameter
> private boolean defer = true;
>
> /**
> * The name of the event that will be triggered if this component
> is the cause of the form submission. The default
> * is {@link EventConstants#SELECTED}.
> */
> @Parameter(allowNull = false, defaultPrefix =
> BindingConstants.LITERAL)
> private String event = EventConstants.SELECTED;
>
> /**
> * If true, then the field will render out with a disabled
> attribute
> * (to turn off client-side behavior). When the form is submitted,
> the
> * bound value is evaluated again and, if true, the field's value
> is
> * ignored (not even validated) and the component's events are not
> fired.
> */
> @Parameter("false")
> private boolean disabled;
>
> @Parameter(defaultPrefix = BindingConstants.LITERAL)
> private String type;
>
> /**
> * The list of values that will be made available to event handler
> method of this component when the form is
> * submitted.
> *
> * @since 5.1.0.0
> */
> @Parameter
> private Object[] context;
>
> /**
> * Defines the mode, or client-side behavior, for the submit. The
> default is {@link SubmitMode#NORMAL}; clicking the
> * button submits the form with validation. {@link
> SubmitMode#CANCEL} indicates the form should be submitted as a cancel,
> * with no client-side validation. {@link
> SubmitMode#UNCONDITIONAL} bypasses client-side validation, but does not
> indicate
> * that the form was cancelled.
> *
> * @see EventConstants#CANCELED
> * @since 5.2.0
> */
> @Parameter(allowNull = false, defaultPrefix =
> BindingConstants.LITERAL)
> private SubmitMode mode = SubmitMode.NORMAL;
>
> /**
> * CSS class for the element.
> *
> * @since 5.4
> */
> @Parameter(name = "class", defaultPrefix =
> BindingConstants.LITERAL, value =
> "message:private-core-components.submit.class")
> private String cssClass;
>
> @Environmental
> private FormSupport formSupport;
>
> @Environmental
> private Heartbeat heartbeat;
>
> @Inject
> private ComponentResources resources;
>
> @Inject
> private Request request;
>
> @Inject
> private JavaScriptSupport javascriptSupport;
>
> @SuppressWarnings("rawtypes")
> @Environmental
> private TrackableComponentEventCallback eventCallback;
>
> private String clientId;
>
> @SuppressWarnings("serial")
> private static class ProcessSubmission implements
> ComponentAction<Html5Button>
> {
> private final String clientId, elementName;
>
> public ProcessSubmission(String clientId, String
> elementName)
> {
> this.clientId = clientId;
> this.elementName = elementName;
> }
>
> public void execute(Html5Button component)
> {
> component.processSubmission(clientId, elementName);
> }
> }
>
> public Html5Button()
> {
> }
>
> Html5Button(Request request)
> {
> this.request = request;
> }
>
> void beginRender(MarkupWriter writer)
> {
> clientId = javascriptSupport.allocateClientId(resources);
>
> String l_name =
> formSupport.allocateControlName(resources.getId());
>
> // Save the element, to see if an id is later requested.
>
> writer.element("button",
>
> "type", type,
>
> "name", l_name,
>
> "data-submit-mode",
> mode.name().toLowerCase(),
>
> "class", cssClass,
>
> "id", clientId);
>
> if (disabled)
> {
> writer.attributes("disabled", "disabled");
> }
>
> formSupport.store(this, new ProcessSubmission(clientId,
> l_name));
>
> resources.renderInformalParameters(writer);
> }
>
> void afterRender(MarkupWriter writer)
> {
> writer.end();
> }
>
> void processSubmission(String clientId, String elementName)
> {
> if (disabled || !selected(clientId, elementName))
> return;
>
> // TAP5-1658: copy the context of the current Submit
> instance so we trigger the event with
> // the correct context later
> final Holder<Object[]> currentContextHolder =
> Holder.create();
> if (context != null)
> {
> Object[] currentContext = new
> Object[context.length];
> System.arraycopy(context, 0, currentContext, 0,
> context.length);
> currentContextHolder.put(currentContext);
> }
>
> Runnable sendNotification = new Runnable()
> {
> public void run()
> {
> // TAP5-1024: allow for navigation result
> from the event callback
> resources.triggerEvent(event,
> currentContextHolder.get(), eventCallback);
> }
> };
>
> // When not deferred, don't wait, fire the event now
> (actually, at the end of the current
> // heartbeat). This is most likely because the Submit is
> inside a Loop and some contextual
> // information will change if we defer.
>
> if (defer)
> formSupport.defer(sendNotification);
> else
> heartbeat.defer(sendNotification);
> }
>
> private boolean selected(String clientId, String elementName)
> {
> // Case #1: via JavaScript, the client id is passed up.
>
> String raw =
> request.getParameter(Form.SUBMITTING_ELEMENT_ID);
>
> if (InternalUtils.isNonBlank(raw) &&
> new
> JSONArray(raw).getString(0).equals(clientId))
> {
> return true;
> }
>
> String name = elementName;
>
> String value = request.getParameter(name);
>
> return value != null;
> }
>
> /**
> * Returns the component's client id. This must be called after
> the component has rendered.
> *
> * @return client id for the component
> */
> public String getClientId()
> {
> return clientId;
> }
> }
>
>
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