QueryDsl - 具有字符串值的case表达式

Question

QueryDsl 3.3.4
Hibernate 3.6.10-Final我有两个实体:

public class Document {
    private Confirmation confirmation;
}

public class Confirmation {
    ...
}

我需要这样的查询:

SELECT count(d.id), CASE WHEN d.confirmation_id IS NULL then 'NOT_CONFIRMED' else 'CONFIRMED' END as confirmed FROM document d GROUP BY confirmed;

所以它应该按照上面的case表达式的结果进行分组.
现在,将案例部分翻译为querydsl:

StringExpression confirmExp = new CaseBuilder()
    .when(Expressions.booleanTemplate("confirmation_id is null"))
    .then(Expressions.stringTemplate("NOT_CONFIRMED"))
    .otherwise(Expressions.stringTemplate("CONFIRMED"));

我正在使用.when(Expressions.booleanTemplate("confirmation_id is null"))以避免加入confirmation桌面.使用这样的表达式运行查询我在下面得到一个例外.
这是另一个hibernate错误或这种情况需要不同吗？

java.lang.IllegalStateException:没有节点的数据类型:> org.hibernate.hql.ast.tree.CaseNode + - [CASE] CaseNode:'case'| + - [WHEN] SqlNode:'when'| | + - [IS_NULL] IsNullLogicOperatorNode:'为null'| | | - [IDENT] IdentNode:'confirmation_id'{originalText = confirmation_id} | | - [IDENT] IdentNode:'NOT_CONFIRMED'{originalText = NOT_CONFIRMED} | - [ELSE] SqlNode:'else'| - [IDENT] IdentNode:'CONFIRMED'{originalText = CONFIRMED}

org.hibernate.hql.ast.tree.SelectClause.initializeExplicitSelectClause(SelectClause.java:156)

Answer 1

如果您想在查询中使用字符串文字,则需要将其写为

StringExpression confirmExp = new CaseBuilder()
    .when(Expressions.booleanTemplate("confirmation_id is null"))
    .then(Expressions.stringTemplate("'NOT_CONFIRMED'"))
    .otherwise(Expressions.stringTemplate("'CONFIRMED'"));

Expressions.stringTemplate并不意味着参数被序列化为String文字,但创建的表达式的类型为java.lang.String.