from json to a ruby hash?

I can go one way using

require 'json'

def saveUserLib(user_lib)
    File.open("/Users/name/Documents/user_lib.json","w") do |f|
    f.write($user_lib.to_json)
    end
end

uname = gets.chomp
$user_lib["_uname"] = uname
saveUserLib($user_lib)

but how do i get it back again as my user_lib?

Solution 1:

You want JSON.parse or JSON.load:

def load_user_lib( filename )
  JSON.parse( IO.read(filename) )
end

The key here is to use IO.read as a simple way to load the JSON string from disk, so that it can be parsed. Or, if you have UTF-8 data in your file:

  my_object = JSON.parse( IO.read(filename, encoding:'utf-8') )

I've linked to the JSON documentation above, so you should go read that for more details. But in summary:

• json = my_object.to_json — method on the specific object to create a JSON string.
• json = JSON.generate(my_object) — create JSON string from object.
• JSON.dump(my_object, someIO) — create a JSON string and write to a file.
• my_object = JSON.parse(json) — create a Ruby object from a JSON string.
• my_object = JSON.load(someIO) — create a Ruby object from a file.

Alternatively:

def load_user_lib( filename )
  File.open( filename, "r" ) do |f|
    JSON.load( f )
  end
end

Note: I have used a "snake_case" name for the method corresponding to your "camelCase" saveUserLib as this is the Ruby convention.

Solution 2:

JSON.load will do the trick. Here's an example that goes both ways:

>> require 'json'
=> true
>> a = {"1" => "2"}
=> {"1"=>"2"}
>> b = JSON.dump(a)
=> "{\"1\":\"2\"}"
>> c = JSON.load(b)
=> {"1"=>"2"}