问 QueryDSL按计算字段排序

EN

在我们的应用程序中，我们使用querydsl来获取实体并将其转换为表示对象。这个表示对象有一个名为 active 的字段。这取决于实体的某个日期是在今天之前(active = false)还是在今天之后(active = true)。这样做一切都很顺利。问题出在尝试按该表达式( QEntity.someDate > today )排序时。这使得hibernate抛出这个错误：

org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected AST node: > near line 3, column 40 [select object.someField as someAlias, (object.someDate > ?1) as active, object as objectAlias
from com.example.Object object
order by object.someDate > ?1 asc]

我按如下方式创建 OrderSpecifier ：

    @Override
    public OrderSpecifier<?> getOrderByClause(SortKey sortKey) {
        BooleanExpression expression = getBooleanPath(); // This is the expression: (object.someDate > ?1)
        if (sortKey.getSortOrder() == ESortOrder.ASCENDING) {
            return new OrderSpecifier(Order.ASC, expression);
        return new OrderSpecifier(Order.DESC, expression);
    }

我也是这样试过的：

    @Override
    public OrderSpecifier<?> getOrderByClause(SortKey sortKey) {
        BooleanExpression expression = getBooleanPath();
        if (sortKey.getSortOrder() == ESortOrder.ASCENDING) {
            return new CaseBuilder().when(expression.isFalse()).then(1).otherwise(2).asc();
        return new CaseBuilder().when(expression.isTrue()).then(1).otherwise(2).desc();
    }

这会导致类似的错误：

org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected AST node: > near line 3, column 40 [select object.someField as someAlias, (object.someDate > ?1) as active, object as objectAlias
from com.example.Object object
order by case when (object.someDate > ?1 = ?2) then ?3 else 2 end asc]

最后像这样：

    @Override
    public OrderSpecifier<?> getOrderByClause(SortKey sortKey) {
        BooleanExpression expression = getBooleanPath();
        if (sortKey.getSortOrder() == ESortOrder.ASCENDING) {
            return new CaseBuilder().when(expression.eq(true)).then(1).otherwise(2).asc();
        return new CaseBuilder().when(expression.eq(true)).then(1).otherwise(2).desc();
    }

，它抛出的错误与前面的