How to get thespecific entity from google app engine datastore according to the specific button click

Question

How to get thespecific entity from google app engine datastore according to the specific button click

233 views Asked by Sandeep At 16 December 2013 at 05:50

My Jsp file is like this. It has 2 buttons. When i click on 1st button then 1st entity from the datastore should be selected and same with the 2nd button.

 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 pageEncoding="ISO-8859-1"%>
 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
 "http://www.w3.org/TR/html4/loose.dtd"> 
 <html>
 <head>
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 <title>Insert title here</title>
 </head>
 <body>
    <body style="background-color:black;">


 <p>
  <p><input type="button" name="first" value="0C F0 0400" style="background-     
 color:#006600; color:#FFFFFF ; height:100px; width:200px"    
 onclick="location.href='hello';"> </p>
<p><input type="button" name="first" value="0D F0 0800" style="background-  
color:#006600; color:#FFFFFF ; height:100px; width:200px" 
 onclick="location.href='hello';">
</p>

</body>
</html>

This is the servlet. How to get the 1st entity on the 1st button click and 2nd entity on the 2nd button click.

package pack.exp;
import java.io.IOException;
import javax.servlet.http.*;

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.EntityNotFoundException;
 import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;


@SuppressWarnings("serial")
public class HelloServlet extends HttpServlet 
{
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws   
    IOException 
{
    Key k1 = KeyFactory.createKey("Employee","E1");    
    Key k2 = KeyFactory.createKey("Employee","E2");        

    String firstName1 = "Sam";
    String lastName1 = "Well";

    String firstName2 = "John";
    String lastName2 = "Morgan";


    Entity bs1 = new Entity(k1);
    Entity dm1 = new Entity(k2);

    bs1.setProperty("FN", firstName1);     
    bs1.setProperty("LN", lastName1); 

    dm1.setProperty("FN", firstName2);     
    dm1.setProperty("LN", lastName2);

    DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
    datastore.put(bs1);
    datastore.put(dm1);

    Entity bs2 = null;
    Entity dm2 = null;

    try 
    {
        bs2= datastore.get(k1);
        dm2= datastore.get(k2);
    }

    catch (EntityNotFoundException e) 
    {
        e.printStackTrace();
    }

    String fName1= (String) bs2.getProperty("FN");
    String lName1= (String) bs2.getProperty("LN");

    String fName2= (String) dm2.getProperty("FN");
    String lName2= (String) dm2.getProperty("LN");

    resp.setContentType("text/plain");
    resp.getWriter().println("Person1 Details------> " + fName1 + "  " + lName1);   

    resp.getWriter().println("Person2 Details------> " + fName2 + "  " + lName2);   

}
}

Original Q&A

There are 1 answers

**Bharathi** · Answer 1 · 2013-12-16 08:05:08

First you need to store the value into the datastore using doGet() method of servlet.

You can do that using this code:

public void doGet(HttpServletRequest req, HttpServletResponse resp) throws   
IOException 
{
   Entity employee1=new Entity("Employee","Employee1");  
   Entity employee2=new Entity("Employee","Employee2");
   employee1.setProperty("FN", "Sam");     
   employee1.setProperty("LN", "Sam"); 
   employee2.setProperty("FN", "John");     
   employee2.setProperty("LN", "Morgan");   
  DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
try{
       datastore.put(employee1);
      datastore.put(employee2);
   }
   catch(DatastoreFailureException d){
        d.printStackTrace();
    }
}

Then in the doPost Method get the value for the button clicked. JSP code I have answered in your other question.

public void doPost(HttpServletRequest req, HttpServletResponse resp) throws   
IOException 
{
String key=req.getParameter("good");
Key key = KeyFactory.createKey("Employee", key);
Entity employee=datastore.get(key);
resp.setContentType("text/plain");
resp.getWriter().println("Person Details------> " + employee.getProperty("FN")+ "  " +employee.getProperty("LN"));
}

TechQA.

How to get thespecific entity from google app engine datastore according to the specific button click

There are 1 answers

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