Playframework scala howto create temp variable

Question

Hi So I have a while loop:

@for(i <- 0 until consoles.size) {
    ... Do something
    ... Add records to a column
}

But what I would like to add a variable and depending on what is going on add it to a different group. For example:

@var column = 0;
@for(i <- 0 until consoles.size) {
        @if(consoles[i].groupname != consoles[i - 1].groupname) {
             column = column + 1;
        }
        ... Do something
        ... Add records to a column
    }

Is this possible. The only thing I have found is by passing in a variable and using that but I would prefer not to do that, although it will only be an int so not sending alot more information to the client I would prefer if I could just declare in the scala template?

Any help would be appreciated.

+1, just hitting this issue now. Having to wrap great swaths of code with @defining is annoying, but not being able to use a mutable var is a major PITA, particularly when dealing with nested loops. How do I stop iterating through an inner loop when I have no state counter to work with? — virtualeyes
– virtualeyes, Commented Oct 22, 2012 at 21:10

Maxime Dantec · Accepted Answer · 2012-07-02 09:09:27Z

6

In your case there are better solutions. Since templates are in scala, you can use some great methods from Collections' API, such as groupBy :

@myList.groupBy(_.groupname).map {
    case (group, items) => {
        <h2>@group</h2>
        @items.map { item =>
            ...
        }
    }
}

Scala templates doesn't require Scala skills, but you need at least to understand the lists API, it's a true life saver !

edited Jul 2, 2012 at 9:09

answered Jul 2, 2012 at 8:50

Maxime Dantec

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kheraud · Accepted Answer · 2012-07-02 14:33:54Z

3

In play templates you can't define var. Furthermore, in Scala you are encouraged to use immutable objects rather than mutable ones.

You have two alternatives to do what you want:

Use a more scala idiomatic way as @Maxime answered
Deal with vals

In addition to @Maxime's answer, you can create new vals in your template using defining

From play 2 documentation :

@defining(user.firstName + " " + user.lastName) { fullName =>
    <div>Hello @fullName</div>
}

edited Jul 2, 2012 at 14:33

answered Jul 2, 2012 at 7:27

kheraud

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4 Comments

Daniel C. Sobral Over a year ago

That won't make fullname a var.

kheraud Over a year ago

True. You can't define a var in play2 templates. You have to : a) define vals b) use a more functional way as @Maxime answered. My answer was dealing with a) but wasn't that clear.

user1434177 Over a year ago

Thanks for that if I use @defining does this declare a string? or can I use this object as an int?

kheraud Over a year ago

The function prorotype is def defining[T](t: T)(handler: T => Any), you can use any type.

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