@Column（unique = true）使這個參數容易驗證像@Size

Question

有沒有什麼辦法使@Column(unique=true)易於驗證，就像它適用於@Size？如果用戶名不是唯一的，我想收到一條消息並將其顯示給用戶。

@Size(min = 3, max = 10, message = "username length should be between {min} and {max}") 
@Column(name = "USERNAME", unique = true, nullable = false, length = 45) 
private String username; 

我驗證數據是這樣的：

Set<ConstraintViolation<User>> constraintViolations = validator.validate(user); 
if (constraintViolations.isEmpty()) { 
    model.addUser(user); 
} else { 
    String message = ""; 
    for (ConstraintViolation constraintViolation : constraintViolations) { 
     message += constraintViolation.getMessage() + "; "; 
    } 
    messageWindowController.display("Incorrect data", message, 14); 
} 

Answer 1

不，你需要編寫自定義驗證和你自己的約束註解。