Twirl: tags/views with optional content

Question

I want to create a tag with optional content... Let's say that I have a tag:

app/views/tags/part.scala.html:

@(param: String)(content: Html = null)

@if(content == null) {
    @param: Your tag has no content...
} else {
    @param: @content
}

And I'd like to use it in my views as:

@tags.part("foo"){ <b>Good!</b} }

or

@tags.part("bar")

Unfortunately second call gives me the compilation error:

missing arguments for method apply in object part;

follow this method with `_' if you want to treat it as a partially applied function

How can I pass it without using @tags.part("bar"){ } or @tags.part("bar"){_} (and check in tag if body != "_")?

Answer 1

Your call:

@tags.part("bar")

is curry call - it returns function apply - not a object.

The solution for your code is call apply function:

@tags.part("bar")()

If you want to call:

@tags.part("bar")

you should to define

@(param: String)(implicit content: Html) 

and define implicit Html in context, or define as

@(param: String,content: Html = null)

• but then you have to call:

@tags.part("foo")(Html("<b>Good!</b>")) - what is error prone.

The work around for last solution is to create method and call it:

@good = {<b>Good!</b>}

@tags.part("foo")(good)