source: src/main/java/com/example/repository/UserRepository.java

package com.example.repository;

import com.example.model.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import java.util.Optional;

@Repository
public interface UserRepository extends JpaRepository<User,Integer> {
    Optional<User> findByUsernameAndPassword(String username, String password);
    Optional<User> findByUsername(String username);
}