我是Scalatra初学者,我有以下路线:
get("/todos") {
contentType = formats("json")
val userid : Int = params.getOrElse("userid", halt(400)).toInt
val limit : Int = params.getOrElse("limit", "0").toInt
val offset : Int = params.getOrElse("offset", "0").toInt
if(limit != 0 && offset != 0)
from(TodoDb.todos)(todo => where(todo => todo.userid == userid) select(todo)).toList
else {
from(TodoDb.todos)(todo => where(todo => todo.userid == userid) select(todo) orderBy(todo.modified)).page(offset, limit).toList
}
}
我无法编译它,我收到以下错误消息:
[info] Compiling 1 Scala source to /home/coelho/www/p.zomg.hu/gfmwa-todo-app/target/scala-2.10/classes...
[error] /home/coelho/www/app/src/main/scala/hu/gfmwa/todoapp/TodoScalatraServlet.scala:25: missing parameter type
[error] from(TodoDb.todos)(todo => where(todo => todo.userid == userid) select(todo)).toList
[error] ^
[error] /home/coelho/www/app/src/main/scala/hu/gfmwa/todoapp/TodoScalatraServlet.scala:27: missing parameter type
[error] from(TodoDb.todos)(todo => where(todo => todo.userid == userid) select(todo) orderBy(todo.modified)).page(offset, limit).toList
[error] ^
[error] two errors found
[error] (compile:compile) Compilation failed
我从这里学习:http://squeryl.org/selects.html 和这里:http://squeryl.org/pagination.html
我无法在这些页面上看到参数类型信息,我无法弄清楚,可能是什么问题。我做错了什么?
where
不希望内部有一个函数(todo=>
),而只是一个布尔的东西。因此,要使您的代码正常工作,请编写类似 from(TodoDb.todos)(todo => where(todo.userid === userid) select
.
顺便说一句,我建议在看到像(todo => where (todo =>
这样的代码片段(双重"待办事项"定义)时立即保持谨慎。