简体   繁体   中英

Springboot + thymeleaf displaying database contents in html table

I'm trying to learn how to make a web app using springboot and thymeleaf. As an exercise I want to display two columns from a random database table I have created in mysql (persons) in a simple html table.

I've used a couple of tutorials for this and wrote the code below however my html does not display the contents of the database only the table header. I have absolutely no idea where I got it wrong. I looked up other questions here and they were all using something called jpa. Is that better than my approach? If so where can I find a begginer's tutorial.

Code

The app class

package ro.database.jdbcTest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;
import ro.database.jdbcTest.controllers.UsersController;

@SpringBootApplication
@EnableAsync
public class App
{
    @Autowired
    UsersController service;

    public static void main( String[] args )
    {
        SpringApplication.run(App.class);
    }

}

The controller

package ro.database.jdbcTest.controllers;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import ro.database.jdbcTest.model.Users;
import ro.database.jdbcTest.services.UserService;

import java.util.List;
import java.util.Map;


@Controller
public class UsersController {

    @Autowired
    UserService service;

    @RequestMapping(value = "/user", method = RequestMethod.GET)
    public String index(Model md){
        md.addAttribute("user", service.findAll());

        return "user";
    }
}

Service class

package ro.database.jdbcTest.services;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Service;
import ro.database.jdbcTest.model.Users;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

@Service
public class UserService {

    @Autowired
    JdbcTemplate template;

    public List<Users> findAll() {
        String sql = "select * from people";
        RowMapper<Users> rm = new RowMapper<Users>() {
            @Override
            public Users mapRow(ResultSet resultSet, int i) throws SQLException {
                Users user = new Users(resultSet.getInt("id"),
                        resultSet.getString("name"),
                        resultSet.getInt("age"));
                String email = resultSet.getString("email");
                if (email != null) {
                    user.setEmail(email);
                }

                return user;
            }
        };

        return template.query(sql, rm);
    }

And the model class

package ro.database.jdbcTest.model;

public class Users {

        private int id;
        private String name;
        private int age;
        private String email;

        public Users(int id, String name, int age){
            this.id=id;
            this.name=name;
            this.age=age;
        }

        public void setEmail(String email){
            this.email=email;
        }
}

Html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h2>Users</h2>
<table border="1">
    <tr>
        <th>name</th>
        <th>age</th>
    </tr>
    <tr th:each = "user: ${users}">
        <td th:text="${user.name}">vasile</td>
        <td th:text="${user.age}">45</td>
    </tr>
</table>
</body>
</html>

You have bind Users in variable user in modelAttribute . Try to bind as users cause in HTML you used users as list

md.addAttribute("users", service.findAll());
return "user";

The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.

 
粤ICP备18138465号  © 2020-2024 STACKOOM.COM