Re: Referencing Hash Values from Keys

Well, I think I'm just not familiar with FM yet, and I'm running this as
a Maven FMPP Ant Task, so what it seems was happening was that it was
pulling in a different config file than I thought, and that config file
didn't have a "poolConnections" value in one of the "pools", and since
FM isn't as lenient with missing keys it was throwing an error.  Looks
like I need to add some existence checking prior to accessing the hash
value.  Sorry for the false alarm.  I'm going to keep at it, but I think
it was just user-error.  Thanks for checking!

-Ryan

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Daniel
Dekany
Sent: Tuesday, October 27, 2009 1:48 AM
To: FMPP open discussion
Subject: Re: [FMPP] Referencing Hash Values from Keys

Tuesday, October 27, 2009, 5:45:11 AM, Shelley, Ryan wrote:

> I'm new to Freemarker, but have used other templating languages in
> the past.  Currently, I'm attempting to use FMPP to generate
> configuration files, but having a bit of difficulty referencing hash
> values from keys.  Here is my TDD and sample template:
>  
> TDD:
>  
> {
>       pools: [
>             {
>                   poolName: Foo
>                   poolConnections: ServiceA
>             },
>             {
>                   poolName: Bar
>                   poolConnections: ServiceB
>             }
>       ]
> }
>  
> Template:
>  
> This will output fine:
> <#list pools as pool>
>       <#assign keys = pool?keys >
>       <#list keys as key>
>             ${key} = ${pool[key]}
>       </#list>
> </#list>
>  
> This will get an error on poolConnections:
> <#list pools as pool>
>       ${pool.poolName}
>       ${pool.poolConnections}
> </#list>
>  
> In the first list iteration, everything is output correctly, but I
> have no control over the keys.  However, the second iteration fails
> on "${pool.poolConnections}" with the error:
>  
> Caused by: freemarker.core.InvalidReferenceException: Expression
> pool.poolConnections is undefined (notice the error is not on
pool.poolName)
>
> If I take "${pool.poolConnections}" out, it works fine (I see the
> value for poolName), but I kind of need to be able to access
"poolConnections"!
>  
> I've tried this with different combinations of

Don't... it should work the way you tried to do it:
pool.poolConnections

I copy-pasted your above snippets into an FMPP project and it works
fine here. Even if you use different versions than me, I don't know
about any bugs in FreeMarker or FMPP bugs that would spoil a such
basic operation. Are you absolutely sure you don't have a typo
somewhere, and that you look at the files that your project actually
uses?

> "${pool[poolConnections]}" and "${pool['poolConnections']}" and
> "${pool.get(poolConnections)}" but none seem to be correct.  I've
> been back and forth through the documentation and the examples, but
> none seem to cover accessing a hash value by it's key directly.

FreeMarker documentation does. It's myMap.myKey or
myMap[WhateverExpressionThatEvaluatesToAString] (like myMap["myKey"]
or myMap[aVariable], myMap["foo_" + i], etc.).

> Suggestions?  Thanks!
>  
> -Ryan

-- 
Best regards,
 Daniel Dekany


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