JSON serializing and deserializing with special characters with RAILS - ruby-on-rails

Question

I really feel a bit stupid as to what to do to make this simple line work, I looked around, and no answer seemed to really answer this, can anyone can tell me how to serialize and deserialize something as simple as that:
JSON.parse("É".to_json)
JSON::ParserError: 757: unexpected token at '"\u00e9"'
EDIT:
The real problem was more akin to saving a hash in the database with a é in the string, like this:
{"Hu00c9MO":"JOUR"}
It seems the string is not good, and I can't bring back the é after decoding from JSON

Answer 1

I think the problem is not the "É". I just tried this:
JSON.parse("A".to_json)
JSON::ParserError: 757: unexpected token at '"A"'
And as you can see it throws the same type of error.
The problem here is that a single string as "É" is not a valid JSON, and even though you can use to_json to serialize it, when you try to parse it, it will hang. Try this for example:
JSON.parse({'key' => 'É'}.to_json)
As stated in the docs:
JSON.generate only allows objects or arrays to be converted to JSON
syntax. to_json, however, accepts many Ruby classes even though it
acts only as a method for serialization
(.to_json is just an alternative to JSON.generate)

Answer 2

Accord http://www.json.org/ JSON should be an object {id: value} or an array [value1, value2].
You are passing to parse only a value. Try something like: JSON.parse(["É"].to_json) or JSON.parse({value: "É"}.to_json)
EDIT As Question was Edited:
Accord http://www.json.org When JSON is on object {id: value}, id can be Any UNICODE charecter except " or \ or control charecter This is the reason why you can't get back "É" in the id side.
Maybe the solution is replace "\" with another valid character before save into DB and do the reverse replace when you read it from DB or just escape "\" with "\".