From: Ammar Ali <ammarabuali@...>
Date: 2010-07-12T05:51:24+09:00
Subject: Re: How to pass a hash as a param to a method called through eval?

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On Sun, Jul 11, 2010 at 11:29 PM, Alex Stahl <astahl@hi5.com> wrote:

> Thanks, but... tried that already and it fails without even calling the
> method:
>
> "...undefined method `com' for nil:NilClass  (NoMethodError)"
>
> So I tried that w/ single quotes too:
>
> eval("#{call['action']}('#{call['params']}')")
>
> and that works, but still passes the params as a string, not a hash.  :(
>


The argument should be a string, that's what eval expects. The problem with
the first version (without the parentheses) was syntax. I don't know where
the "com" or the nil:NilClass are coming from. Is there something missing
from your code sample?

Here's what I get in irb:

mini:~ ammar$ rvm use 1.9.1
info: Using ruby 1.9.1 p378
mini:~ ammar$ irb
ruby-1.9.1-p378 > require 'json'
 => true
ruby-1.9.1-p378 > def some_func(hash); puts "from function:
#{hash.inspect}"; end
 => nil
ruby-1.9.1-p378 > j = '{ "action": "some_func", "params": { "a": "foo", "b":
"bar" } }'
 => "{ \"action\": \"some_func\", \"params\": { \"a\": \"foo\", \"b\":
\"bar\" } }"
ruby-1.9.1-p378 > call = JSON.parse(j)
 => {"action"=>"some_func", "params"=>{"a"=>"foo", "b"=>"bar"}}
ruby-1.9.1-p378 > eval("#{call['action']}(#{call['params']})")
from function: {"a"=>"foo", "b"=>"bar"}
 => nil

Ammar

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