I have the following code in Play 2.0 template:

@content.toString.lines.map{
    case line =>     // i put `case` here as another attempt to make it work
    line match {
        case "" => @Html("")
        case _ => <li>@Html(line)</li>   /*CRASH*/
    }   
}

It fails on the marked line, saying that not found: value line . The second variant of it:

@for(line <- content.toString.lines){
    @line match {                            /*CRASH*/
        case "" => @Html("")
        case _ => <li>@Html(line)</li>
    }   
}

fails on the marked line, claiming that 'case' expected but identifier found .

UPDATE:

Same thing goes for val :

@val headID = "head"

comes up with illegal start of simple expression .

UPDATE ENDS

I would like to know, what am I doing wrong and how to correctly implement the match-case structure and val assignment in Play's templates?

---

Using match expressions in templates

You need to enclose in braces (“{” and “}”) the HTML content of your templates:

@for(line <- content.toString.lines) {
  @line match {
    case "" => { }
    case _ => { <li>@Html(line)</li> }
  }
}

In your specific case, the following code would read better IMHO:

@content.toString.lines.collect {
  case line if !line.isEmpty => { <li>@Html(line)</li> }
}

Defining values

You can define values using the defining[T](value: T)(usage: T => Html) helper:

@defining(1 + 2 * 3) { value =>
  <div>@value</div>
}

---

我发现在外面添加一个{}以包含整个代码会起作用

@{content.toString.lines.map{ line => 
  line match {
    case "" =>  @Html("")
    case _ => <li>@Html(line)</li> 
}}  

---

following seems to work for me

@content.toString.lines.map{ line => 
    line match {
      case "" =>  @Html("")
     case _ => <li>@Html(line)</li> 
}  

hard on eyes, but you can look at target/scala-2.9.1/src_managed/main/views/html/index.template.scala in the play project directory to see what its putting in string literals.

As for val assignment, I don't know, but @defining may help

链接地址: http://www.djcxy.com/p/62634.html

上一篇: 模式匹配语言知识，模式匹配方法

下一篇: Scala`match`和`val`不能在视图模板中编译