光滑的3动态groupby-其列表中的字段[字符串]

问题描述

让我说我想执行查询:

select columnName1,columnName2,Sum(*)
from table
group by columnName1,columnName2

其中columnName1，columnName2是从list [string]("columnName1"，columnName2)提供的

where columnName1,columnName2 is supplied from list[string] ("columnName1",columnName2")

我该如何使用光滑的呢?如果列在编译时是已知的，那么我可以轻松地使用groupBy函数:

how can i do it with slick?if the columns are known by compile time, i can easily use the groupBy function:

tableQuery.groupBy { r => (r.columnName1,r.columnName2)}.map (case groupName,group) => (groupName._1,groupName._2,group.map(...).avg)}

但是动态呢?

推荐答案

您可以使用r.column("foo")语法在运行时动态访问列，所以我相信您可以执行以下操作?

You can use the r.column("foo") syntax to access columns dynamically at runtime, so I believe you can just do something like the following?

columnNames = List("col1", "col2")
tableQuery
    .groupBy(r => columnNames.map(name => r.column(name)))
    .map({ case (groupName, group) => /* do something with it */})

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