EclipseLink无法获取标量布尔值

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问题描述

以下JPA条件查询在Hibernate上成功运行(最终版本为4.2.7).

The following JPA criteria query succeeds on Hibernate (4.2.7 final).

CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder();
CriteriaQuery<Boolean>criteriaQuery=criteriaBuilder.createQuery(Boolean.class);
Root<UserTable> root = criteriaQuery.from(entityManager.getMetamodel().entity(UserTable.class));
criteriaQuery.multiselect(root.get(UserTable_.enabled));

ParameterExpression<String>parameterExpression=criteriaBuilder.parameter(String.class);
criteriaQuery.where(criteriaBuilder.equal(criteriaBuilder.lower(criteriaBuilder.trim(root.get(UserTable_.emailId))), criteriaBuilder.lower(criteriaBuilder.trim(parameterExpression))));
List<Boolean> list = entityManager.createQuery(criteriaQuery).setParameter(parameterExpression, "admin").getResultList();

for(Boolean o:list)
{
    System.out.println("enabled : "+o);
}

这仅仅是为了从MySQL数据库返回标量布尔值.对应的列在MySQL中的类型为TINYINT(1).

It is simply meant to return a scalar Boolean value from MySQL database. The corresponding column is of type TINYINT(1) in MySQL.

它将生成以下SQL语句.

It generate the following SQL statement.

SELECT
    usertable0_.enabled as col_0_0_
FROM
    social_networking.user_table usertable0_
WHERE
    lower(trim(BOTH FROM usertable0_.email_id))=lower(trim(BOTH FROM ?))

同一查询在EclipseLink(2.5.1)上失败，在这种情况下，不返回任何内容(无错误，无异常).但是，它会生成如下正确的SQL语句.

The same query fails on EclipseLink (2.5.1) in which case it returns nothing (no error, no exception). It however, generates a correct SQL statement as follows.

SELECT enabled
FROM projectdb.user_table
WHERE (LOWER(TRIM(email_id)) = LOWER(TRIM(?)))

bind => [admin]

对应的JPQL就像这样

The corresponding JPQL like so,

SELECT u.enabled
FROM UserTable u
WHERE lower(trim(u.emailId))=lower(trim(:emailId))

也没有得到有问题的值.

also doesn't get the value in question.

但是，它可与其他列配合使用，如下所示.

It however, works with additional columns as shown below.

CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder();
CriteriaQuery<Object[]>criteriaQuery=criteriaBuilder.createQuery(Object[].class);
Root<UserTable> root = criteriaQuery.from(entityManager.getMetamodel().entity(UserTable.class));
criteriaQuery.multiselect(root.get(UserTable_.enabled), root.get(UserTable_.firstName));

ParameterExpression<String>parameterExpression=criteriaBuilder.parameter(String.class);
criteriaQuery.where(criteriaBuilder.equal(criteriaBuilder.lower(criteriaBuilder.trim(root.get(UserTable_.emailId))), criteriaBuilder.lower(criteriaBuilder.trim(parameterExpression))));
List<Object[]> list = entityManager.createQuery(criteriaQuery).setParameter(parameterExpression, userName).getResultList();

添加了另外一列root.get(UserTable_.firstName)，并且CriteriaQuery的返回类型从CriteriaQuery<Boolean>更改为CriteriaQuery<Object[]>.

One extra column root.get(UserTable_.firstName) is added and the return type of CriteriaQuery is changed from CriteriaQuery<Boolean> to CriteriaQuery<Object[]>.

该列在相应的实体中定义如下.

The column is defined as follows in the corresponding entity.

@Basic(optional = false)
@NotNull
@Column(name = "enabled")
private Boolean enabled;  //Getter and setter.

为什么在EclipseLink中没有给出布尔值?

Why doesn't it given a Boolean value in EclipseLink?

EclipseLink

EclipseLink无法获取标量布尔值

问题描述

推荐答案