reiern70 commented on a change in pull request #467: URL: https://github.com/apache/wicket/pull/467#discussion_r611436687
########## File path: wicket-core/src/main/java/org/apache/wicket/markup/html/form/upload/OnFilesSelectedBehavior.java ########## @@ -0,0 +1,134 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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 org.apache.wicket.markup.html.form.upload; + +import java.util.ArrayList; +import java.util.List; +import javax.servlet.http.HttpServletRequest; +import org.apache.wicket.Component; +import org.apache.wicket.WicketRuntimeException; +import org.apache.wicket.ajax.AjaxRequestTarget; +import org.apache.wicket.ajax.attributes.AjaxRequestAttributes; +import org.apache.wicket.ajax.attributes.IAjaxCallListener; +import org.apache.wicket.ajax.form.AjaxFormSubmitBehavior; +import org.apache.wicket.ajax.form.OnChangeAjaxBehavior; +import org.apache.wicket.markup.head.IHeaderResponse; +import org.apache.wicket.markup.head.JavaScriptHeaderItem; +import org.apache.wicket.request.IRequestParameters; +import org.apache.wicket.request.Request; +import org.apache.wicket.request.cycle.RequestCycle; +import org.apache.wicket.request.resource.JavaScriptResourceReference; +import org.apache.wicket.request.resource.ResourceReference; +import org.apache.wicket.util.lang.Args; +import org.apache.wicket.util.string.StringValue; +import org.danekja.java.util.function.serializable.SerializableBiConsumer; +import org.danekja.java.util.function.serializable.SerializableConsumer; +import com.github.openjson.JSONArray; +import com.github.openjson.JSONObject; +import com.github.openjson.JSONTokener; + +/** + * {@link org.apache.wicket.ajax.form.OnChangeAjaxBehavior} that streams back to server properties + * of the selected file (at client side), even when file has not yet being uploaded. + * s * + * + * @author Ernesto Reinaldo Barreiro (reier...@gmail.com). + */ +public abstract class OnFilesSelectedBehavior extends OnChangeAjaxBehavior { + + private static final long serialVersionUID = 1L; + + private static final ResourceReference JS = new JavaScriptResourceReference(OnFilesSelectedBehavior.class, "OnFilesSelectedBehavior.js"); + + @Override + protected void onBind() { + super.onBind(); + Component component = getComponent(); + if (!(component instanceof FileUploadField)) { + throw new WicketRuntimeException("Behavior " + getClass().getName() + + " can only be added to an instance of a FileUploadField"); + } + } + + @Override + protected void onUpdate(AjaxRequestTarget target) { + Request request = RequestCycle.get().getRequest(); + List<FileDescription> fileDescriptions = new ArrayList<>(); + IRequestParameters parameters = request.getRequestParameters(); + // data is streamed as JSON. + StringValue fileInfos = parameters.getParameterValue("fileInfos"); + JSONArray jsonArray = new JSONArray(fileInfos.toString()); + for (int i = 0; i < jsonArray.length(); i++) { + fileDescriptions.add(new FileDescription((JSONObject)jsonArray.get(i))); + } + onSelected(target, fileDescriptions); + } + + + /** + * Called when a file, at client side is selected. + * + * @param target The {@link org.apache.wicket.ajax.AjaxRequestTarget} + * @param fileDescriptions A list of FileDescription + */ + protected abstract void onSelected(AjaxRequestTarget target, List<FileDescription> fileDescriptions); + + @Override + protected void updateAjaxAttributes(AjaxRequestAttributes attributes) + { + super.updateAjaxAttributes(attributes); + attributes.getAjaxCallListeners().add(new IAjaxCallListener() + { + @Override + public CharSequence getPrecondition(Component component) + { + return "return Wicket.OnFilesSelected.precondition(this, '" + component.getMarkupId() + "');"; + } + }); + attributes.getDynamicExtraParameters().add("return Wicket.OnFilesSelected.collectFilesDetails('" + getComponent().getMarkupId() + "');"); + } + + @Override + public void renderHead(Component component, IHeaderResponse response) + { + response.render(JavaScriptHeaderItem.forReference(JS)); + super.renderHead(component, response); + } + + /** + * Creates an {@link OnFilesSelectedBehavior} based on lambda expressions + * + * @param select {@link SerializableBiConsumer} + * + * @return the {@link org.apache.wicket.markup.html.form.upload.OnFilesSelectedBehavior} behavior + */ + public static OnFilesSelectedBehavior select( + SerializableBiConsumer<AjaxRequestTarget, List<FileDescription>> select) Review comment:  ? -- This is an automated message from the Apache Git Service. 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