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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

我在这些页面上看不到参数类型信息，我无法弄清楚，可能是什么问题。我做错了什么？

4

1 回答 1

2

where不期望 ( todo=>) 内部有一个函数，而只是一个布尔值。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 =>（双重“待办事项”定义）这样的代码片段时要立即小心。

于 2013-09-18T10:52:52.227 回答