Setting title in a template when it is not a String literal

[Harshdeep S Jawanda]

​How do I set the title of a page when that value has be retrieved from a parameter passed to the Rythm template?

I have a base template and a template that extends it. In the extending template I have to use the value from a parameter to set the title of the page. So, for example:

@extends(base, title: @aParameter.getName() )

but the above code doesn't seem to work. Also, this doesn't let me check whether aParameter is non-null. Is there a way I can set the value of the title parameter later in the body (since @set is now deprecated)?

Thanks.

[Harshdeep S Jawanda]

So I found out the answer by hit-and-trial:

@extends(base, title: aParameter.getName() )

Just had to leave out the "@" near the beginning.

Please note: in my case the @import and @args statements precede the @extends() statement.

--
Regards,
Harshdeep S Jawanda

[Harshdeep S Jawanda]

Please note: I still have not found a way to check whether aParameter is non-null before I call a method on it to get the value of the page title. Any suggestions?

In the docs I've only seen so far:

@if (aParameter) {aParameter.getName()} else {""}

etc., but that doesn't work when passing an argument to a base template that I am extending.

[Harshdeep S Jawanda]

A better way to put this --- how do I achieve the following in current Rythm code:

@args Parameter aParameter

@extends(base)

@if (aParameter) {

    @set("title" : aParameter.getName())

} else {

    @set("title" : "Default title")

}

[Roman Bykovskiy]

Maybe it’s because your code do nothing. 

If you need to render the value of Parameter.getName() - you should add @ sign before:

@if(aParameter){

  @aParameter.getName()

} 

-- 

Roman Bykovskiy

На 28 апреля 2014 г. в 11:46:58, Harshdeep S Jawanda (hsja...@gmail.com) написал:

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[green]

You can't set to parent template fields at the time the template is rendering. Use @get() and @set(). Checkout http://fiddle.rythmengine.org/#/editor/45d2594b867749519fc88aa4af722d93

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[Harshdeep S Jawanda]

Even if I write:

@extends(base, title: @if (aParameter) {@aParameter.getName()} else {"No such article"})

I still don't get any output.

[Harshdeep S Jawanda]

Yes, I had verified that @set works... but then I get deprecated warnings. Was trying to avoid that.

[Roman Bykovskiy]

If you trying not to render but pass param you shouldn’t use any of @ 

So if you pass params - it’s just a typical java way:

@extends(base, title: if(aParameter!=null){aParameter.getName()}else {"No such article"})

If you check it in render:

template:

@extends(base, title: aParameter)

base wrapper:

@if(aParameter){

  @aParameter.getName()

}

-- 

Roman Bykovskiy

На 28 апреля 2014 г. в 12:25:16, Harshdeep S Jawanda (hsja...@gmail.com) написал:

[Roman Bykovskiy]

i’m sorry, for the first one, the correct java way: 

@extends(base, title: aParameter.getName()!=null?aParameter.getName:"No such article")

also you can redefine your getter in a aParameter class:

public String getName(){

  if(this.name==null) return "No such article"

  return this.name

}

-- 

Roman Bykovskiy

На 28 апреля 2014 г. в 12:29:07, Roman Bykovskiy (802...@gmail.com) написал:

[Harshdeep S Jawanda]

I tried this and it resulted in a syntax error: Syntax error on token "if", invalid Expression

I cannot check aParameter for null in the base template as not all extending templates get an object of type aParameter. Yes, I could use the value of aParameter.toString() but I don't want to do that, semantically it seems too generic and an abuse of the toString method. Plus, depending on the object, Object.toString() may not be what I want to show.

The 2nd method you suggested doesn't work either (if written as: @extends(base, title: null != aParameter ? aParameter.getName() : "No such article")

If I write @extends(base, title: (null != aParameter) ? aParameter.getName() : "No such article") , then an error is generated ("java.lang.Boolean cannot be cast to java.lang.String") --- the only difference being putting a pair of parentheses around null != aParameter.

As far as I can make out, using @set is the only way that works (as Gelin suggested).

Roman: my concern is not that the field name inside aParameter might be null (that's already handled), my concern is that aParameter itself might be null. So doing a null check on this.name doesn't work --- the NullPointerException would have already happened.

Thanks everybody for your help.

[Roman Bykovskiy]

That’s odd… It works for me.

Anyway, one more way: you can just define new variable in template

@{

  String myTitle = "No such article";

  if(aParameter!=null && aParameter.title!=null)

    myTitle = aParameter.getName();

}

@extends(base,title: myTitle);

-- 

Roman Bykovskiy

На 28 апреля 2014 г. в 12:56:07, Harshdeep S Jawanda (hsja...@gmail.com) написал:

[Harshdeep S Jawanda]

Yeah... already tried that... isn't working for me...

I am using Rythm 1.0.1-SNAPSHOT. Which version are you using?

[Harshdeep S Jawanda]

I am wondering if I am using the correct version of Rythm...

In my pom.xml I have:

    <parent>
        <groupId>org.sonatype.oss</groupId>
        <artifactId>oss-parent</artifactId>
        <version>7</version>
    </parent>

    ...

        <dependency>
            <groupId>org.rythmengine</groupId>
            <artifactId>rythm-engine</artifactId>
             <version>1.0.1-SNAPSHOT</version>
        </dependency>

Is this correct?

Other configuration (just in case it makes any difference):

• GAE SDK 1.8.8
• Eclipse Kepler
• Mac OS 10.9.2
  

[green]

Your pom.xml is correct

[Roman Bykovskiy]

Maybe the problem in your object?

Just try to render your object in template, render this new var in template. 

— 

Roman Bykovskiy

На 28 апреля 2014 г. в 15:00:50, Harshdeep S Jawanda (hsja...@gmail.com) написал:

[Harshdeep S Jawanda]

Other than setting the page title (which is of course defined in the base template), the object and its various properties work fine in the extending template.