ActionValidator.java

/*
 * Copyright 2011 ArcBees Inc.
 *
 * 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 com.gwtplatform.dispatch.rpc.server.actionvalidator;

import com.gwtplatform.dispatch.rpc.shared.Action;
import com.gwtplatform.dispatch.rpc.shared.Result;
import com.gwtplatform.dispatch.shared.ActionException;

/**
 * Implementers must provide an implementation of this interface and provide it to the
 * {@link com.gwtplatform.dispatch.rpc.shared.DispatchService DispatchService} implementation so that it can check
 * whether or not the action can be executed. Doing so will often require session information, which can be done by
 * injecting a {@code Provider<HttpSession>} into the validator and calling {@code httpSessionProvider.get()} within the
 * {@link #isValid} method.
 * <p/>
 * You should think of annotating your validators with {@code @RequestScoped} or {@code @Singleton}.
 */
public interface ActionValidator {
    /**
     * Validate whether or not that {@link Action} can be executed at this time. You can also throw an
     * {@link ActionException} if you want to fine grain why the validator failed.
     *
     * @param action The action that called this validator.
     * @return {@code true} if the action can be executed, {@code false} otherwise.
     */
    boolean isValid(Action<? extends Result> action) throws ActionException;
}