EditableValueHolder.java

/*
 * Copyright 2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package javax.faces.component;

import javax.faces.el.MethodBinding;
import javax.faces.event.ValueChangeListener;
import javax.faces.validator.Validator;

/**
 * Defines the methods required for a component whose value can be
 * modified by the user.
 * <p>
 * When a component implementing this interface is rendered, the value
 * output is (in order):
 * <ul>
 * <li>The "submitted value" if non-null.
 * <li>The component's "local value" if non-null.
 * <li>The result of evaluating the value-binding expression with name
 *  "value" for this component.
 * </ul>
 * <p>
 * Rendering the submitted value if non-null allows a component to redisplay
 * a user-provided value when validation fails for the component. The
 * submitted value is usually just the plain string extracted from the
 * servlet request. During successful validation of the component, the
 * submitted value is converted to an appropriate datatype, and stored as
 * the component's "local value", and then the "submitted value" is
 * immediately reset to null. 
 * <p>
 * Rendering the "local value" if non-null allows a component to redisplay
 * a page when validation fails for some other component; the model can't
 * be updated unless <i>all</i> components have passed validation. This
 * also allows components to work without a defined "value" value-binding
 * expression. When all components validate, the update model phase runs;
 * all components with "value" value-bindings store the "local value" into
 * the specified property then reset their local value to null.
 * <p>
 * Rendering the value-binding expression named "value" allows components
 * to display data from the user's model classes. This is the most common
 * way a component's renderer obtains the value to display.
 * 
 * see Javadoc of <a href="http://java.sun.com/j2ee/javaserverfaces/1.1_01/docs/api/index.html">JSF Specification</a> for more.
 * 
 * @author Manfred Geiler (latest modification by $Author$)
 * @version $Revision$ $Date$
 */
public interface EditableValueHolder
        extends ValueHolder
{
    /**
     * Get an object representing the most recent raw user input
     * received for this component.
     * <p>
     * This is non-null only between <code>decode</code> and
     * <code>validate</code> phases, or when validation for the
     * component has not succeeded. Once conversion and validation has
     * succeeded, the (converted) value is stored in the local "value"
     * property of this component, and the submitted value is reset to null.
     */
    public Object getSubmittedValue();

    /**
     * Invoked during the "decode" phase of processing to inform this
     * component what data was received from the user.
     * <p>
     * In many cases the submitted value is a plain string extracted
     * from the current servlet request object.
     * <p>
     * In cases where a component is rendered as multiple input components
     * (eg a calendar control with separate day/month/year fields), the
     * submittedValue may be some custom object wrapping the data.
     * However the provided object <i>must</i> be able to represent all
     * possible user input values, not just valid ones.
     */
    public void setSubmittedValue(Object submittedValue);

    /**
     * Determine whether the value member variable of this component has
     * been set from the converted and validated "submitted value". This
     * property is needed because EditableValueHolder components need
     * to distinguish between the value local <i>member</i> and the
     * value <i>property</i> (which may involve a value-binding to the
     * user model).
     */
    public boolean isLocalValueSet();

    /**
     * Specify the return value of method isLocalValueSet. This is called
     * after the local value member has been set from the converted and
     * validated "submitted value". It is cleared after that value has
     * been pushed to the user model via the value-binding named "value".
     */
    public void setLocalValueSet(boolean localValueSet);

    /**
     * This returns false if validation has been run for this component
     * and has failed.
     * <p>
     * It is also set to false if the validated value could not be passed
     * to the model during the update model phase.
     * <p>
     * All input components are marked as valid during the "restore view"
     * phase, so this will return true for components whose validation
     * has not been executed.
     */
    public boolean isValid();

    public void setValid(boolean valid);

    /**
     * Return true if this component must have a non-empty submitted
     * value.
     * <p>
     * Note that even when a component is "required", it is not an 
     * error for some form to be submitted which does not contain
     * the component. It is only an error when the form submitted
     * does contain the component, but there is no data for the
     * component in that request. A "submitted value" of null is
     * set during the "decode" step to represent the case where
     * the request map has no entry corresponding to this component's
     * id. When the decode step finds an entry in the request, but
     * the corresponding value represents "no data" (eg an empty
     * string for a text input field) then some special non-null
     * value must be set for the "submitted value"; validation
     * for "required" fields must then check for that.
     */
    public boolean isRequired();

    /**
     * Set to true to cause validation failure when a form
     * containing this component is submitted and there is no
     * value selected for this component.
     */
    public void setRequired(boolean required);

    /**
     * When true, the validation step for this component will also
     * invoke any associated actionListeners. Typically such listeners
     * will call renderResponse, causing the rendering phase to begin
     * immediately (including possible navigation) without performing
     * validation on any following components.
     */
    public boolean isImmediate();

    public void setImmediate(boolean immediate);

    /**
     * Get the single validator defined directly on this component.
     * <p>
     * In addition to this validator, there may be a list of validators
     * associated with this component.
     * <p>
     * This validator is executed after all validators in the validator list.
     */
    public MethodBinding getValidator();

    public void setValidator(javax.faces.el.MethodBinding validatorBinding);

    /**
     * Get the single value-change defined directly on this component.
     * <p>
     * In addition to this listener, there may be a list of listeners
     * associated with this component.
     * <p>
     * This listeners is executed after all listeners in the list.
     */
    public MethodBinding getValueChangeListener();

    public void setValueChangeListener(MethodBinding valueChangeMethod);

    public void addValidator(Validator validator);

    public Validator[] getValidators();

    public void removeValidator(Validator validator);

    public void addValueChangeListener(ValueChangeListener listener);

    public ValueChangeListener[] getValueChangeListeners();

    public void removeValueChangeListener(ValueChangeListener listener);
}