JSON to Hash in Ruby and vice-versa using Files - Parser Error

Question

I am trying to save data from a Hash to a file. I convert it to JSON and dump it into the file. When I try to parse back from file to hash I get JSON::ParserError

Code to convert Hash to JSON file: (works fine)

user = {:email => "[email protected]", :passwrd => "hardPASSw0r|)"}

student_file = File.open("students.txt", "a+") do |f|
        f.write JSON.dump(user)
end

After adding a few values one by one to the file it looks something like this:

{"email":"[email protected]","passwrd":"qwert123"}{"email":"[email protected]","passwrd":"qwert12345"}{"email":"[email protected]","passwrd":"hardPASSw0r|)"}

I tried the following code to convert back to Hash but it doesn't work:

file = File.read('students.txt')
data_hash = JSON.parse(file)

I get

System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/json/common.rb:155:in `parse': 757: unexpected token at '{"email":"[email protected]","passwrd":"qwert12345"}{"email":"[email protected]","passwrd":"hardPASSw0r|)"}' (JSON::ParserError)
    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/json/common.rb:155:in `parse'
    from hash_json.rb:25:in `<main>'

My goal is to be able to add and remove values from the file. How do I fix this, where was my mistake? Thank you.

you are write file with a+ so you append one json object to another. is it what you need? can't you write without append? — Aleksey
– Aleksey, Commented Nov 14, 2016 at 9:07
@Aleksey I don't have to use +a no. How does the solution go in that case? — Airwavezx
– Airwavezx, Commented Nov 14, 2016 at 9:14

damoiser · Accepted Answer · 2016-11-14 09:27:10Z

1

This should work:

https://repl.it/EXGl/0

# as adviced by @EricDuminil, on some envs you need to include 'json' too
require 'json'

user = {:email => "[email protected]", :passwrd => "hardPASSw0r|)"}

student_file = File.open("students.txt", "w") do |f|
  f.write(user.to_json)
end 

file = File.read('students.txt')

puts "saved content is: #{JSON.parse(file)}"

p.s. hope that this is only an example, never store passwords in plain-text! NEVER ;-)

edited Nov 14, 2016 at 9:27

answered Nov 14, 2016 at 9:22

damoiser

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2 Comments

Eric Duminil Over a year ago

Yes. Depending on your environment, you might want to require 'json' first.

damoiser Over a year ago

correct @EricDuminil - I will add your suggestion to my code-snippet. Thanks.

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