Re: (no subject)

Thursday, November 28, 2013, 1:45:53 PM, Albert Kam wrote:

> Hello, i'm currently trying to dump my object as a json with freemarker (latest version).
>
> And so i started looking around for existing solution and found one at :
> http://ericbrandel.com/2013/03/28/freemarker-container-to-json/
> I've pasted the macro on the end of the mail.
>
> Now the problem is when i tried it out, i seem to find an
> enumerable type, which cannot be enumerated ?
> Here's the exception i got :
>
> Getting the number of items or enumerating the items is not
> supported on this sequence+method (wrapper: f.e.b.SimpleMethodModel)

This used to happen if you have a method like `Whatever foo(int
index)`, and so then you could write something like `${foo[i]}`, which
actually does the same as `${foo(i)}`. It doesn't make much sense
IMHO, but it's like that for ages and backward compatibility must be
kept. So `foo` is a sequence as you can apply `[index]` on it, but you
can't enumerate it as its impossible to query the sequence size.

> value. (Hint 1: Maybe you wanted to call this method first and then
> do something with its return value. Hint 2: Getting items by intex
> possibly works, hence it's a "+sequence".) 
> And this happened on the line of :
> <#elseif object?is_enumerable> 
> ...
> <#list object as item> 
>
> Now i wonder whether i can do a check in the ftl whether this can
> be enumerated or not before i actually enumerate it ?

With ?enumerable... except that the author of ?enumerable didn't
thought about these odd sequence-like-methods. I will fix that.
Meanwhile, you can fix it be using your own TemplateMethodModelEx for
detecting this. (Or by risking that if something ?is_sequence &&
?is_method then it's never really a sequence... I'm not sure if that's
true though.)

> Currently i dont know which field causes that, and why it's not enumerable.
>
> The complete macro :
>
> <#macro objectToJsonMacro object> 
> <@compress single_line=true> 
>     <#if object?is_hash || object?is_hash_ex>

A hash_ex is always a hash, so you only need the is_hash

>         <#assign first="true"> 
>         { 
>         <#list object?keys as key> 
>             <#if first="false">,</#if> 
>             <#assign value><@objectToJsonMacro object=object<key> /></#assign>
>             "${key}" : ${value?trim} 
>             <#assign first="false"> 
>         </#list> 
>         } 
>     <#elseif object?is_enumerable>

&& !isSimpleMethodModel(object)

where isSimpleMethodModel will have to be implement by you. Or you
pre-patch FreeMarker...

>         <#assign first="true"> 
>         [ 
>         <#list object as item> 
>             <#if first="false">,</#if> 
>             <#assign value><@objectToJsonMacro object=item /></#assign>
>             ${value?trim} 
>             <#assign first="false">

You don't need this `first` thing. <#if item_has_next>,</#if>.

>         </#list> 
>         ] 
>     <#else> 
>         "${object?trim}" 
>     </#if> 
> </@compress> 
> </#macro> 
>
> Regards,
> Bertie

-- 
Thanks,
 Daniel Dekany


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