Question

Have been hacking together a couple of libraries, and had an issue where a string was getting ‘double escaped’.

for example:
Fixed example

 > x = ['a']
 => ["a"] 
 > x.to_s
 => "[\"a\"]" 
 > 

Then again to

\"\[\\\"s\\\"\]\"

This was happening while dealing with http headers. I have a header which will be an array, but the http library is doing it’s own character escaping on the array.to_s value.

The workaround I found, was to convert the array to a string myself, and then ‘undo’ the to_s. Like so:
formatted_value = value.to_s

if value.instance_of?(Array)
  formatted_value = formatted_value.gsub(/\\/,"") #remove backslash                                                 
  formatted_value = formatted_value.gsub(/"/,"")  #remove single quote
  formatted_value = formatted_value.gsub(/\[/,"") #remove [                                                                                                     
  formatted_value = formatted_value.gsub(/\]/,"") #remove ]   
end
value = formatted_value

… There’s gotta be a better way … (without needing to monkey-patch the gems I’m using). (yeah, this break’s if my string actually contains those strings.)

Suggestions?

** UPDATE 2 **

Okay. Still having troubles in this neighborhood, but now I think I’ve figured out the core issue. It’s serializing my array to json after a to_s call. At least, that seems to be reproducing what I’m seeing.

[‘a’].to_s.to_json

I’m calling a method in a gem that is returning the results of a to_s, and then I’m calling to_json on it.

Answer 1

I’ve edited my answer due to your edited question:

I still can’t duplicate your results!

>> x = ['a']
=> ["a"]
>> x.to_s
=> "a"

But when I change the last call to this:

>> x.inspect
=> "[\"a\"]"

So I’ll assume that’s what you’re doing?

it’s not necessarily escaping the values – per se. It’s storing the string like this:

%{["a"]}

or rather:

'["a"]'

In any case. This should work to un-stringify it:

>> x = ['a']
=> ["a"]
>> y = x.inspect
=> "[\"a\"]"
>> z = Array.class_eval(y)
=> ["a"]
>> x == z
=> true

I’m skeptical about the safe-ness of using class_eval though, be wary of user inputs because it may produce un-intended side effects (and by that I mean code injection attacks) unless you’re very sure you know where the original data came from, or what was allowed through to it.