java JPA 实体验证
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JPA Entity Validation
提问by s.susini
Ok, I'm trying to setup an application in a Java EE Container. I use JPA for persistence and I also use the javax.validation.constraints.*constraints. By default the container validate the entities during the @PrePersistand @PreUpdatelifecycle events and it's good for me, but how do I handle the ConstraintViolationException?
好的，我正在尝试在 Java EE 容器中设置应用程序。我将 JPA 用于持久性，并且我也使用javax.validation.constraints.*约束。默认情况下，容器在@PrePersist和@PreUpdate生命周期事件期间验证实体，这对我有好处，但是我该如何处理ConstraintViolationException？
I can't find any docs on it, any suggestion is welcomed.
我找不到任何文档，欢迎提出任何建议。
回答by Pascal Thivent
Well, you could catch it :) Here is an example (from a unit test):
好吧，你可以抓住它:) 这是一个例子（来自单元测试）：
public class CustomerTest {
private static EntityManagerFactory emf;
private EntityManager em;
@BeforeClass
public static void createEntityManagerFactory() {
emf = Persistence.createEntityManagerFactory("MyPu");
}
@AfterClass
public static void closeEntityManagerFactory() {
emf.close();
}
@Before
public void beginTransaction() {
em = emf.createEntityManager();
em.getTransaction().begin();
}
@After
public void rollbackTransaction() {
if (em.getTransaction().isActive()) {
em.getTransaction().rollback();
}
if (em.isOpen()) {
em.close();
}
}
@Test
public void nameTooShort() {
try {
Customer customer = new Customer("Bo");
em.persist(customer);
em.flush();
fail("Expected ConstraintViolationException wasn't thrown.");
} catch (ConstraintViolationException e) {
assertEquals(1, e.getConstraintViolations().size());
ConstraintViolation<?> violation = e.getConstraintViolations().iterator().next();
assertEquals("name", violation.getPropertyPath().toString());
assertEquals(Size.class, violation.getConstraintDescriptor().getAnnotation().annotationType());
}
}
}
Where my Customer looks like:
我的客户看起来像：
@Entity
public class Customer {
@Id @GeneratedValue
@NotNull
private Long id;
@NotNull
@Size(min = 3, max = 80)
private String name;
private boolean archived;
...
}
But this was just an example to show a tiny part of the API.
但这只是展示 API 一小部分的示例。
In my opinion, you should actually handle the validation at the view level. Many presentation frameworks support Bean Validation: JSF 2.0, Wicket, Spring MVC...
在我看来，您实际上应该在视图级别处理验证。许多表示框架都支持 Bean Validation：JSF 2.0、Wicket、Spring MVC...
See also
也可以看看
回答by pihentagy
You can catch ConstraintViolationException, as Pascaldescribed it, but please be aware, that this Exception could be thrown anytimeafter your create/update statement, and before the end of the transaction (see FlushModeType). Typical throwing points are when you read something after your create/update statement, or at an explicit flush()statement (which you should use with caution).
你能赶上ConstraintViolationException，如帕斯卡尔描述它，但请注意，这个异常可能会被抛出任何时候你创建/更新语句之后，交易结束前（见FlushModeType）。典型的问题是当您在创建/更新语句之后或在显式flush()语句（您应该谨慎使用）处阅读某些内容时。
