Models and repositories

We'll need to create the model layer and the data access layer. These are the parts of our application that deal with handling data models and persisiting data using the database.

Models

Models are classes that we use to represent data within the application.

package com.bleeter.models;

public class User {
  private final Integer id;
  private String username;
  private boolean verified;

  public User(Integer id, String username, boolean verified) {
    this.id = id;
    this.username = username;
    this.verified = verified;
  }

  // methods...

}

Repositories

Repositories are classes that interact with the database to let us persist, modify, and delete this data.

package com.bleeter.repositories;

import com.bleeter.models.User;
import com.bleeter.DB;
import java.util.List;

public class UserRepository {
  public static List<User> findAll() {}
  public static User findById(int _id) {}
  public static User create(String username, boolean verified) {}
}

The aim is to use our repository like this:

var user = UserRepository.findById(7);
System.out.println(user.getUsername());

Querying for data

We can use our database connection to get data from the database.

public static List<User> findAll() throws Exception {
  var query = "SELECT id, username, verified FROM users";

  try (var connection = DB.getConnection();
      var statement = connection.prepareStatement(query);
      var resultSet = statement.executeQuery();) {

    var users = new ArrayList<User>();

    while (resultSet.next()) {
      var id = resultSet.getInt("id");
      var username = resultSet.getString("username");
      var verified = resultSet.getBoolean("verified");
      users.add(new User(id, username, verified));
    }

    return users;
  }
}