How to convert a ruby hash object to JSON? So I am trying this example below & it doesn't work?
I was looking at the RubyDoc and obviously Hash object doesn't have a to_json method. But I am reading on blogs that Rails supports active_record.to_json and also supports hash#to_json. I can understand ActiveRecord is a Rails object, but Hash is not native to Rails, it's a pure Ruby object. So in Rails you can do a hash.to_json, but not in pure Ruby??
car = {:make => "bmw", :year => "2003"}
car.to_json
4 Answers
One of the numerous niceties of Ruby is the possibility to extend existing classes with your own methods. That's called "class reopening" or monkey-patching (the meaning of the latter can vary, though).
So, take a look here:
car = {:make => "bmw", :year => "2003"}
# => {:make=>"bmw", :year=>"2003"}
car.to_json
# NoMethodError: undefined method `to_json' for {:make=>"bmw", :year=>"2003"}:Hash
# from (irb):11
# from /usr/bin/irb:12:in `<main>'
require 'json'
# => true
car.to_json
# => "{"make":"bmw","year":"2003"}"
As you can see, requiring json has magically brought method to_json to our Hash.
require 'json/ext' # to use the C based extension instead of json/pure
puts {hash: 123}.to_json
You can also use JSON.generate:
require 'json'
JSON.generate({ foo: "bar" })
=> "{\"foo\":\"bar\"}"
Or its alias, JSON.unparse:
require 'json'
JSON.unparse({ foo: "bar" })
=> "{\"foo\":\"bar\"}"
Add the following line on the top of your file
require 'json'
Then you can use:
car = {:make => "bmw", :year => "2003"}
car.to_json
Alternatively, you can use:
JSON.generate({:make => "bmw", :year => "2003"})
