CODEWITHSUNDEEP
htmljspservletssetattributegetattribute
Carmen
Carmen

Reputation: 1

JSP is not correctly receiving information from an array coming from a servlet

I am trying to create a project where I use a servlet to pass information to a JSP page. The problem is that I can't get the JSP to generate what I expect.

To explain further, in the servlet I retrieve information from a database and store it in an array (in my case, the values are 2 and 3). But when I pass it to the JSP, I can't seem to store that information in another array and then display it on the screen. If I use ${partidas}, it gives me the desired value of 2,3. But when I use `<% List<Integer> partidas = (List<Integer>) request.getAttribute("partidas");` nothing is stored. I have included my code below. Servlet:

import java.io.;
import javax.servlet.;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.;
import java.sql.;
import java.util.*;

public class PartidasAMedias extends HttpServlet {
protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {

    Connection con;
    Statement st;
    ResultSet rs;
    PrintWriter out;

    String SQL, Nombre;
    int IdUsu, Estado;

    List<Integer> partidas = new ArrayList<Integer>();
    try { Nombre = req.getParameter("nombreRecogido"); System.out.println("Nombre: " + Nombre);
    Class.forName("com.mysql.cj.jdbc.Driver"); 
    con = DriverManager.getConnection("jdbc:mysql://localhost/cuatroenraya", "root", ""); 
    st = con.createStatement(); SQL = "SELECT IdUsuario FROM usuarios WHERE Nombre ='" + Nombre + "'"; 
    rs = st.executeQuery(SQL);
        if (rs.next()) {
            System.out.println("2." + rs.getInt("IdUsuario"));
            IdUsu = rs.getInt("IdUsuario");
            SQL = "SELECT IdPartida, Estado FROM partidas WHERE Creador ='" + IdUsu + "' OR Invitado = '" + IdUsu + "'";
            rs = st.executeQuery(SQL);
            if (rs.next()) {
                
                Estado = rs.getInt("Estado");
                while (rs.next()) {
                    if (Estado == 1) {
                        int idPartida = rs.getInt("IdPartida");
                        System.out.println("3." + idPartida);
                        partidas.add(rs.getInt("IdPartida"));
                        System.out.println("Partida agregada: " + rs.getInt("IdPartida"));
                    }
                }
                System.out.println("4."+ partidas);
                HttpSession session = req.getSession(true);
                //session.setAttribute("partidas", partidas);
                req.getSession().setAttribute("partidas", partidas);
                System.out.println("Redirigiendo a ListadoPartidas.jsp con partidas: " + partidas);
                res.sendRedirect("ListadoPartidas.jsp");

            } else {                
                res.sendRedirect("zSinPartidas.html");
            }

        }
        rs.close();
        st.close();
        con.close();

    } catch (Exception e) {
        System.err.println(e);
    } 
}
}

ListadoPartidas.jsp:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1" %> <%@ page import="java.util.List" %>  
 <!DOCTYPE html>
    <html lang="es" dir="ltr">

    <head>
        <meta http-equiv="Content-Type" contest="text/html; charset=ISO-8859-1">
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>Partidas en curso</title>
    </head>
    <body>
        ${partidas}
        <% List<Integer> partidas = (List<Integer>) request.getAttribute("partidas");
                if (partidas != null && !partidas.isEmpty()) {
                %>
                <table>
                    <thead>
                        <tr>
                            <th>ID Partida</th>
                        </tr>
                    </thead>
                    <tbody>
                        <% for (Integer idPartida : partidas) { %>
                            <tr>
                                <td>
                                    <%= idPartida %>
                                </td>
                            </tr>
                            <% } %>
                    </tbody>
                </table>
                <% } else { %>
                   <p>No hay partidas a medias</p>
                    <% } %>
    </body>
    </html>

The images I am attaching are what the JSP generates and what I can see in the web server console.Web server console jsp

Upvotes: 0

Views: 40

Answers (0)

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