我对springbootwebflux是个新手，我使用cassandra作为我的数据库。我不知道如何用用户名或电子邮件登录。我有三张table
用户表

Create Table user (
   userid bigint,
   username text,
   password text,
   name text,
   email text,
   phone text,
   birthday text,
   biography text,
   PRIMARY KEY (userid)
)

用户\用户名表

Create Table user (
   username text,
   userid bigint,
   password text,
   name text,
   email text,
   phone text,
   birthday text,
   biography text,
   PRIMARY KEY (username)
)

用户电子邮件表

Create Table user (
   email text,
   username text,
   userid bigint,
   password text,
   name text,
   phone text,
   birthday text,
   biography text,
   PRIMARY KEY (email)
)

@PostMapping("/signin")
public Mono<ResponseEntity<?>> login(@RequestBody AuthLoginRequest authLoginRequest) {
   return userService.findByUsernameOrEmail(authLoginRequest.getUsernameOrEmail()).map((user) -> {
      if(passwordEncoder.encode(authLoginRequest.getPassword()).equals(user.getPassword())) {
          return ResponseEntity.ok(new ApiResponse(tokenProvider.generateToken(user)));
      }else {
          return ResponseEntity.status(HttpStatus.UNAUTHORIZED).build();
      }
   }.defaultIfEmpty(ResponseEntity.status(HttpStatus.UNAUTHORIZED).build());
}

这就是问题所在，我将如何返回用户mono。如果他们使用用户名登录，我必须查询user\u username表，或者如果他们使用电子邮件地址登录，我必须查询user\u email表。

@Service
public class UserService() {
   public Mono<User> findByUsernameOrEmail(String usernameOrEmail) {

   }
}

我需要压缩user\u username和user\u email类吗？请我需要一个解决方案，我还没有看到任何有关这个问题。我需要一个有效的解决方案。
根据你的回答@nikolab，我编辑了这个问题来展示我到目前为止所做的一切

public Mono<User> findByUsernameOrEmail(String usernameOrEmail) {
  return userUsernameRepository.findById(usernameOrEmail)
     .map(userUsername -> {
                System.out.println("Checking name "+userUsername.getName());// i printed out the name of the user
                return new User(userUsername);
            }).switchIfEmpty(userEmailRepository.findById(usernameOrEmail)
                .map(userEmail -> {
                        System.out.println("Checking name " +userEmail.getName());// i printed out the name of the user
                        return new User(userEmail);
                    }));
}

一切正常。。。
我的用户表

public class User {
    //My Constructors
    public User(UserUsername userUsername) {
      System.out.println("Userid " + userUsername.getUserId());/I am getting the userId
      User user = new User();
      BeanUtils.copyProperties(userUsername, user);
      System.out.println("New Userid " + user.getUserId()); //I am getting the userId
    }

    public User(UserEmail userEmail) {
      System.out.println("Userid " + userEmail.getUserId()); /I am getting the userId
      User user = new User();
      BeanUtils.copyProperties(userEmail, user);
      System.out.println("New Userid " + user.getUserId()); /I am getting the userId
    }
}

我的帖子Map
这里的用户是空的

@PostMapping("/signin")
public Mono<ResponseEntity<?>> login(@RequestBody AuthLoginRequest authLoginRequest) {
   return userService.findByUsernameOrEmail(authLoginRequest.getUsernameOrEmail()).map((user) -> {
   if(passwordEncoder.encode(authLoginRequest.getPassword()).equals(user.getPassword())) {
          return ResponseEntity.ok(new ApiResponse(tokenProvider.generateToken(user)));
      }else {
          return ResponseEntity.status(HttpStatus.UNAUTHORIZED).build();
      }
   }.defaultIfEmpty(ResponseEntity.status(HttpStatus.UNAUTHORIZED).build());
}