I have a jsp file that is displaying some records from the datastore, and I want to have a delete button next to each entry that would remove it from the db.
So, I know that the Servelet will do the actual deleting, but I’m not sure what to put with the delete button in the jsp, so that my Servlet knows what entity (item) to look up in the database.
Is there a better way to do this?
Here is my jsp. Look down near the bottom where I have my delete button:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="java.util.List" %>
<%@ page import="com.google.appengine.api.users.User" %>
<%@ page import="com.google.appengine.api.users.UserService" %>
<%@ page import="com.google.appengine.api.users.UserServiceFactory" %>
<%@ page import="com.google.appengine.api.datastore.DatastoreServiceFactory" %>
<%@ page import="com.google.appengine.api.datastore.DatastoreService" %>
<%@ page import="com.google.appengine.api.datastore.Query" %>
<%@ page import="com.google.appengine.api.datastore.Entity" %>
<%@ page import="com.google.appengine.api.datastore.FetchOptions" %>
<%@ page import="com.google.appengine.api.datastore.Key" %>
<%@ page import="com.google.appengine.api.datastore.KeyFactory" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<html>
<head>
<link type="text/css" rel="stylesheet" href="/stylesheets/main.css" />
</head>
<body>
<%
String podlistName = request.getParameter("podlistName");
if (podlistName == null) {
podlistName = "default";
}
pageContext.setAttribute("podlistName", podlistName);
UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser();
if (user != null) {
pageContext.setAttribute("user", user);
%>
<p>Hello, ${fn:escapeXml(user.nickname)}! (You can
<a href="<%= userService.createLogoutURL(request.getRequestURI()) %>">sign out</a>.)</p>
<%
} else {
%>
<p>Hello!
<a href="<%= userService.createLoginURL(request.getRequestURI()) %>">Sign in</a>
to include your name with podcasts you post.</p>
<%
}
%>
<%
DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
Key podlistKey = KeyFactory.createKey("Podlist", podlistName);
// Run an ancestor query to ensure we see the most up-to-date
// view of the Greetings belonging to the selected Podlist.
Query query = new Query("Podcast", podlistKey).addSort("date", Query.SortDirection.DESCENDING);
List<Entity> podcasts = datastore.prepare(query).asList(FetchOptions.Builder.withLimit(5));
if (podcasts.isEmpty()) {
%>
<p>Podlist '${fn:escapeXml(podlistName)}' has no items.</p>
<%
} else {
%>
<p>Items in Podlist '${fn:escapeXml(podlistName)}'.</p>
<%
for (Entity podcast : podcasts) {
pageContext.setAttribute("podcast_url",
podcast.getProperty("podcast_url"));
if (podcast.getProperty("user") == null) {
%>
<p>An anonymous person wrote:</p>
<%
} else {
pageContext.setAttribute("podcast_user",
podcast.getProperty("user"));
%>
<p><b>${fn:escapeXml(podcast_user.nickname)}</b> wrote:</p>
<%
}
%>
<blockquote>${fn:escapeXml(podcast_url)}</blockquote>
<form action="/delete" method="post">
<div><input type="submit" value="Delete Podcast" /></div>
<input type="hidden" name="podlistName" value="${fn:escapeXml(podlistName)}"/>
<!-- not sure what to put here to give a reference to this entity-->
<input type="hidden" name="podcast_id" value="$??"/>
</form>
<%
}
}
%>
<form action="/add" method="post">
<div><textarea name="podcast_url" rows="3" cols="60"></textarea></div>
<div><input type="submit" value="Post Podcast" /></div>
<input type="hidden" name="podlistName" value="${fn:escapeXml(podlistName)}"/>
</form>
</body>
</html>
Here is my Servlet:
package com.aol.sharepodder;
import java.io.IOException;
import java.util.Date;
import java.util.UUID;
import java.util.logging.Logger;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;
import com.google.appengine.api.users.User;
import com.google.appengine.api.users.UserService;
import com.google.appengine.api.users.UserServiceFactory;
public class AddPodcastServlet extends HttpServlet {
private static final Logger log = Logger.getLogger(AddPodcastServlet.class.getName());
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
UserService userService = UserServiceFactory.getUserService();
User user = userService.getCurrentUser();
String podlistName = req.getParameter("podlistName");
Key podlistKey = KeyFactory.createKey("Podlist", podlistName);
String podcast_url = req.getParameter("podcast_url");
Date date = new Date();
Entity podcast = new Entity("Podcast", podlistKey);
podcast.setProperty("user", user);
podcast.setProperty("date", date);
podcast.setProperty("podcast_url", podcast_url);
DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
datastore.put(podcast);
resp.sendRedirect("/podlist.jsp?podlistName=" + podlistName);
}
}
thanks!!
It seems like you are already making use of a “podcast_id” – so then why don’t you pass that in the request to the
/deletehandler?Seems hard for us to tell you what you need to pass as it is your application – but what you probably want is to pass a parameter that uniquely refers to the entity (whether that be a “key”, “podcast_id”, etc). Each entity in GAE has a unique key.