java - IN 不工作的 JPA EntityManager createQuery()

Question

这是失败的:

List<String> names = new ArrayList<String>();
names.add("sold");
Query query = em.createQuery("FROM PropField propField WHERE propField.name IN (?)");
query.setParameter(1, names);
List<PropField> fields = query.getResultList();

这也是:

List<String> names = new ArrayList<String>();
names.add("sold");
Query query = em.createQuery("FROM PropField propField WHERE propField.name IN (?)");
query.setParameter(1, names.toArray());
List<PropField> fields = query.getResultList();

这也是:

List<String> names = new ArrayList<String>();
names.add("sold");
Query query = em.createQuery("FROM PropField propField WHERE propField.name IN ?");
query.setParameter(1, names.toArray());
List<PropField> fields = query.getResultList();

以及上述所有其他排列。检查了文档，它说第一个选项应该有效。这是顶部的异常(exception)情况。

java.lang.ClassCastException: java.util.ArrayList cannot be cast to java.lang.String
at org.hibernate.type.StringType.toString(StringType.java:67)

Hibernate 的 HQL 使用 setParameterList，但在这里尝试坚持直接使用 JPA。

Answer 1

来自 JPA 1.0 规范:

4.6.4.1 Positional Parameters

The following rules apply to positional parameters.

• Input parameters are designated by the question mark (?) prefix followed by an integer. For example: ?1.
• Input parameters are numbered starting from 1.
  Note that the same parameter can be used more than once in the query string and that the ordering of the use of parameters within the query string need not conform to the order of the positional parameters.

4.6.4.2 Named Parameters

A named parameter is an identifier that is prefixed by the ":" symbol. It follows the rules for identifiers defined in Section 4.4.1. Named parameters are case sensitive.

Example:

SELECT c
FROM Customer c
WHERE c.status = :stat

Section 3.6.1 describes the API for the binding of named query parameters

所以要么使用(带有命名参数):

List<String> names = Arrays.asList("sold");
Query query = em.createQuery("FROM PropField propField WHERE propField.name IN (:names)");
query.setParameter("names", names)
List<PropField> fields = query.getResultList();

或者(带位置参数):

List<String> names = Arrays.asList("sold");
Query query = em.createQuery("FROM PropField propField WHERE propField.name IN (?1)");
query.setParameter(1, names)
List<PropField> fields = query.getResultList();

两者都使用 Hibernate EM 3.4.0.GA 进行了测试。

请注意，强制使用圆括号包围 IN 子句的参数是一个错误(至少在 JPA 2.0 中)，如 this previous answer 中所述。 .