package org.jboss.errai.ui.client.widget;
import javax.annotation.PostConstruct;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.FormElement;
import com.google.gwt.dom.client.IFrameElement;
import com.google.gwt.dom.client.Style.Display;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.safehtml.client.SafeHtmlTemplates.Template;
import com.google.gwt.user.client.ui.Composite;
/**
* Base class for {@link Template Templated} widgets that require native form
* support for asynchronous {@code GET} or {@code POST} requests.
*
* <p>
* Calls to {@link AbstractForm#submit()} trigger a form submission that is
* null-routed and targets a hidden iframe.
*
* <p>
* The typical usage will be for login forms, where calling
* {@link AbstractForm#submit()} after a successful login will prompt the
* browser to remember a user's credentials.
*
* <p>
* If you use an {@link AbstractForm} and still encounter issues getting proper
* browser form support:
*
* <ul>
* <li>make sure that your text-fields are actual form inputs
*
* <li>make sure the UI "submit" button triggers a {@link ClickHandler} that
* calls {@link AbstractForm}{@link #submit()}
*
* <li>make sure the UI "submit" button does not directly trigger submission
* (i.e. it should <b>not</b> have {@code type="submit"}
*
*
* @author Max Barkley <mbarkley@redhat.com>
*/
public abstract class AbstractForm extends Composite {
public static final String DEFAULT_FORM_ACTION = "0.0.0.0";
public static final String ERRAI_FORM_FRAME_ID = "ERRAI-FORM-FRAME";
private IFrameElement iFrame;
@PostConstruct
private void setupIFrame() {
iFrame = getOrMakeIFrame();
iFrame.getStyle().setDisplay(Display.NONE);
final String uniqueId = ERRAI_FORM_FRAME_ID;
iFrame.setId(uniqueId);
iFrame.setName(uniqueId);
Document.get().getBody().appendChild(iFrame);
}
private void prepareFormForSubmission(final FormElement form) {
form.setMethod("post");
form.setTarget(iFrame.getName());
form.setAction(getFormAction());
}
/**
* Subclasses may override this method if they want the form to submit to a
* different url than {@link AbstractForm#DEFAULT_FORM_ACTION}.
*
* @return The value that will be set to the
* {@link AbstractForm#getFormElement()} {@code action} attribute
* before submission.
*/
protected String getFormAction() {
return DEFAULT_FORM_ACTION;
}
private IFrameElement getOrMakeIFrame() {
IFrameElement iFrame = null;
try {
iFrame = (IFrameElement) Document.get().getElementById(ERRAI_FORM_FRAME_ID);
}
catch (Exception e) {
}
if (iFrame == null)
iFrame = Document.get().createIFrameElement();
return iFrame;
}
/**
* Submit the form returned from {@link AbstractForm#getFormElement()}. Before
* the form is submitted, it will be modifed so that it targets a hidden
* iframe with the id {@link AbstractForm#ERRAI_FORM_FRAME_ID} with the
* {@code action} set to the return value of
* {@link AbstractForm#getFormAction()}.
*/
public void submit() {
final FormElement form = getFormElement();
prepareFormForSubmission(form);
form.submit();
}
/**
* @return The form element that will be submitted when
* {@link AbstractForm#submit()} is called.
*/
protected abstract FormElement getFormElement();
}