DevForce 2012 Punch鸡尾酒存储库查询与选择器搜索最大结果

Question

我正在尝试使用一些参数查询表的最大值（长），尝试使用Punch Framework。

这是原始的LINQ查询：

Table.Where(x=>x.GroupId == 1).Max(x=>x.LongValue)

我想将此LINQ查询转换为使用Cocktail Repository：

(await UnitOfWork.GetRepository<Table>()
            .FindAsync(selector => selector.Select(x => x.LongValue), predicate => predicate.GroupId.Equals(1),))
            .FirstOrDefault();

这适用于选择组的第一个LongValue，但是如何更改查询以获得表的最大结果？

Answer 1

DevForce正确使用AsScalarAsync方法来处理标量查询的异步执行。 Punch并没有直接实现这一点，但您可以扩展您的存储库类来提供此功能。它看起来类似于基类SELECT DESCRIPTION, (SELECT SUM(USAGE) FROM InvoiceDetail WHERE UNIT = @UNIT, InvoiceDate BETWEEN :firstWeekBegin AND :firstWeekEnd as Week1Usage), (SELECT SUM(USAGE) FROM InvoiceDetail WHERE UNIT = @UNIT, InvoiceDate BETWEEN :secondWeekBegin AND :secondWeekEnd as Week2Usage), SELECT PRICE FROM InvoiceDetail WHERE UNIT = @UNIT, InvoiceDate = firstWeekBegin as Week1Price), (SELECT PRICE FROM InvoiceDetail WHERE UNIT = @UNIT, InvoiceDate = secondWeekBegin as Week2Price), FROM InvoiceDetail WHERE UNIT = @UNIT, InvoiceDate BETWEEN @BEGDATE AND @ENDATE ORDER BY PRODUCTS 类如何实现CountAsync。像这样：

Repository<T>

DevForce对Max有几个重载，所以请查看文档以了解哪个最适合您。