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How to convert a ruby hash object to JSON?


Question

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
2016/08/11
1
343
8/11/2016 11:02:16 AM

Accepted Answer

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.

568
5/23/2017 12:34:44 PM

require 'json/ext' # to use the C based extension instead of json/pure

puts {hash: 123}.to_json
2014/08/18

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\"}"
2019/05/17

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"})
2019/11/15

You should include json in your file

For Example,

require 'json'

your_hash = {one: "1", two: "2"}
your_hash.to_json

For more knowledge about json you can visit below link. Json Learning

2019/01/25

Source: https://stackoverflow.com/questions/3183786
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