如何在scala中使用play framework從Mysql得到結果的總和？

Question

我的工作簡單的Scala Web App和我運行一個查詢，然後播放應用程序所賜例外

[RuntimeException的：UnexpectedNullableFound（的ColumnName（.SUM（得分），有些（SUM（得分）））） ]

play.api.Application$$anon$1: Execution exception[[RuntimeException: UnexpectedNullableFound(ColumnName(.SUM(score),Some(SUM(score))))]] 
    at play.api.Application$class.handleError(Application.scala:289) ~[play_2.10.jar:2.1.2] 
    at play.api.DefaultApplication.handleError(Application.scala:383) ~[play_2.10.jar:2.1.2] 
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$18$$anonfun$apply$18.apply(PlayDefaultUpstreamHandler.scala:310) ~[play_2.10.jar:2.1.2] 
    at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$18$$anonfun$apply$18.apply(PlayDefaultUpstreamHandler.scala:308) ~[play_2.10.jar:2.1.2] 
    at play.api.libs.concurrent.PlayPromise$$anonfun$extend1$1.apply(Promise.scala:113) ~[play_2.10.jar:2.1.2] 
    at play.api.libs.concurrent.PlayPromise$$anonfun$extend1$1.apply(Promise.scala:113) ~[play_2.10.jar:2.1.2] 
Caused by: java.lang.RuntimeException: UnexpectedNullableFound(ColumnName(.SUM(score),Some(SUM(score)))) 
    at scala.sys.package$.error(package.scala:27) ~[scala-library.jar:na] 
    at anorm.Sql$.as(Anorm.scala:535) ~[anorm_2.10.jar:2.1.2] 
    at anorm.Sql$class.as(Anorm.scala:453) ~[anorm_2.10.jar:2.1.2] 
    at anorm.SimpleSql.as(Anorm.scala:370) ~[anorm_2.10.jar:2.1.2] 
    at models.Keyword$$anonfun$getBlogScore$1.apply(Keyword.scala:53) ~[na:na] 
    at models.Keyword$$anonfun$getBlogScore$1.apply(Keyword.scala:52) ~[na:na] 

型號/ keyword.scala

def getBlogScore(word: String, blog: String): Long={DB.withConnection{implicit c=> 
SQL("select SUM(score) from keyword where blog like {blog} and word = {word}").on('blog->blog,'word->word).as(scalar[Long].single) 
} 
} 

我想基於一些條件得分列的總和。

給我一些想法來解決這個異常！

Answer 1

我猜SUM返回NULL當沒有行匹配。我也猜測 你可能需要0在這種情況下。

所以你必須處理這種情況。想起了Option。快速查看文檔，grep Option表示有.singleOpt。

所以，你可以嘗試：

def getBlogScore(word: String, blog: String): Long = 
    DB.withConnection { implicit c => 
    SQL("select SUM(score) from keyword where blog like {blog} and word = {word}"). 
     on('blog->blog,'word->word). 
     as(scalar[Long].singleOpt). 
     getOrElse(0L) 
    } 

Answer 2

嘗試：

SQL("select SUM(score) from keyword where blog like {blog} and word = {word}"). 
    on('blog->blog,'word->word). 
    as(scalar[Option[Long]].single). 
    getOrElse(0L) 

Answer 3

來得有點晚，但這個問題是在ANORM主分支：https://github.com/playframework/playframework/pull/2072