Html 在 Play2 Scala 模板中声明变量
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Declare variable in a Play2 scala template
提问by travega
How do you declare and initialize a variable to be used locally in a Play2 Scala template?
如何在 Play2 Scala 模板中声明和初始化要在本地使用的变量？
I have this:
我有这个：
@var title : String = "Home"
declared at the top of the template, but it gives me this error:
在模板顶部声明，但它给了我这个错误：
illegal start of simple expression """),_display_(Seq[Any](/*3.2*/var)),format.raw/*3.5*/(""" title : String = "Home"
采纳答案by virtualeyes
@defining("foo") { title=>
<div>@title</div>
...
}
basically, you have to wrap the block in which you are going to use it
基本上，您必须包装要使用它的块
回答by ollie
Actually, @c4k 's solution is working (and quite convenient) as long as you don't try to change the variable's value afterwards, isn't it?
实际上，只要您之后不尝试更改变量的值，@c4k 的解决方案就可以工作（并且非常方便），不是吗？
You simply place this at the top of your template:
您只需将其放在模板的顶部：
@yourVariable = {yourValue}
or, if it's a more complicated expression, you do this:
或者，如果它是一个更复杂的表达式，你可以这样做：
@yourVariable = @{yourExpression}
You can even work with things like lists like that:
您甚至可以使用类似列表的内容：
@(listFromController: List[MyObject])
@filteredList = @{listFromController.filter(_.color == "red")}
@for(myObject <- filteredList){ ... }
For the given example, this would be
对于给定的示例，这将是
@title = {Home} //this should be at beginning of the template, right after passing in parameters
<h1> Using title @title </h1>
In the comments you said, that it gets typed to HTML type. However, that is only relevant if you try to overwrite @titleagain, isn't it?
在您所说的评论中，它被输入为 HTML 类型。但是，这仅在您尝试@title再次覆盖时才有意义，不是吗？
回答by Govind Singh
scala template supports this, you can define variable in template
scala 模板支持这个，你可以在模板中定义变量
@import java.math.BigInteger; var i=1; var k=1
if you want to change its value in template
如果你想改变它在模板中的值
@{k=2}
example
例子
@(title:String)(implicit session:play.api.mvc.Session)
@import java.math.BigInteger; var i=1; var k=1
^
<div id='LContent_div@i'>
^
<div id='inner_div_@k'></div>
^
</div>
回答by biesior
virtualeyes' solution is the proper one, but there is also other possibility, you can just declare a view's param as usually with default value, in such case you'll have it available for whole template + you'll keep possibility for changing it from the controller:
virtualeyes 的解决方案是正确的解决方案，但还有其他可能性，您可以将视图的参数声明为通常具有默认值，在这种情况下，您将可以将其用于整个模板 + 您将保留更改它的可能性的controller：
@(title: String = "Home page")
<h1>Welcome on @title</h1>
controller:
控制器：
def index = Action{
Ok(views.html.index("Other title"))
}
Note that Java controller doesn't recognise templates' default values, so you need to add them each time:
请注意，Java 控制器无法识别模板的默认值，因此您每次都需要添加它们：
public static Result index(){
return ok(views.html.index.render("Some default value..."));
}
回答by c4k
If you don't want to wrap all your content with @defining, you can do this :
如果您不想用@defining 包装所有内容，您可以这样做：
@yourVariable = { yourValue }
The @defining directive is really unreadable in a template...
@defining 指令在模板中真的不可读......
回答by Suma
There is one obvious solution which looks quite clean and may be preferred sometimes: define a scope around the template, define your variable inside of it, and let the scope produce the html code you need, like this:
有一个明显的解决方案看起来很干净，有时可能更受欢迎：在模板周围定义一个范围，在其中定义变量，然后让范围生成您需要的 html 代码，如下所示：
@{
val title = "Home"
<h1>Welcome on {title}</h1>
}
This has some drawbacks:
这有一些缺点：
- you are generating your html as Scala
NodeSeqthis way, which may be limiting sometimes - there is a performance issue with this solution: the code inside of
@{seems to be compiled runtime, because the Scala code generated for the page loooks like this (some usual Twirl stuff deleted):
- 您以
NodeSeq这种方式将 html 生成为 Scala ，有时可能会受到限制 - 此解决方案存在性能问题：其中的代码
@{似乎是在运行时编译的，因为为页面生成的 Scala 代码看起来像这样（删除了一些常用的 Twirl 内容）：
The generated code:
生成的代码：
...
Seq[Any](format.raw/*1.1*/("""<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Basic Twirl</title>
</head>
<body>
"""),_display_(/*9.10*/{
val title = "Home"
<h1>Welcome on {title}</h1>
}),format.raw/*15.10*/("""
"""),format.raw/*17.5*/("""</body>
</html>"""))
}
}
}
...
回答by Spektakulatius
In twirl templates I would recommend using the defining block, because the
在旋转模板中，我建议使用定义块，因为
@random = @{
new Random().nextInt
}
<div id="@random"></div>
<div id="@random"></div>
would result in different values when used multiple times!
多次使用会导致不同的值！
@defining(new Random().nextInt){ random =>
<div id="@random"></div>
<div id="@random"></div>
}
回答by Eassa Nassar
@isExcel= {@Boolean.valueOf(java.lang.System.getProperty(SettingsProperties.isExcel))}
