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ruby-on-railsjsonrubyruby-on-rails-3ruby-on-rails-4
oj5th
oj5th

Reputation: 1399

Parameterized JSON key naming

I have the following JSON:

{
  my_json: {
    id: 1,
    name: "John"
  }
}

How can I customize key name via parameterized like:

def jsonize(custom_key="id")
{
    my_json: {
      "#{custom_key}": 1,
      name: "John"
    }
  }
end

To be output with:

Scenario 1:

=> jsonize

OUTPUT:

{
  my_json: {
    id: 1,
    name: "John"
  }
}

Scenario 2:

=> jsonize("value")

OUTPUT:

{
  my_json: {
    value: 1,
    name: "John"
  }
}

Upvotes: 2

Views: 360

Answers (3)

Amadan
Amadan

Reputation: 198334

The hash-rocket syntax has been in Ruby since ancient times:

{ :foo => 1, "bar" => 2 }

Ruby 1.9 (I think) introduced a new colon shortcut syntax just for symbols (while keeping the hash-rocket general for any key type):

{ foo: 1, "bar" => 2 }

Ruby 2.2 (I think) introduced the possibility of symbolizing a string in this syntax:

{ "foo": 1, "bar" => 2 }

All of these do the same thing. What you are doing is perfectly grammatical Ruby code -- in a sufficiently new Ruby. In older Rubies, you will need to use the old reliable hash-rocket syntax:

{ "foo".to_sym => 1, "bar" => 2 }

Now that you actually have a string, you can do normal interpolation:

{ "f#{'o' * 2}".to_sym => 1, "bar" => 2 }

In your case, you could write

{ "#{custom_key}".to_sym => 1 }

However, all of this is completely unnecessary, since you can just write simply this, in any Ruby:

{ custom_key.to_sym => 1 }

Even better, since you're just turning everything into JSON immediately after, you don't even need symbolised keys; so these two expressions will have identical results:

{ custom_key.to_sym => 1 }.to_json
{ custom_key => 1 }.to_json

(Also note that what you state as examples of JSON -- both input and output -- are, in fact, not JSON, nor would .to_json output such. In JSON, as opposed to plain JavaScript object literal, keys must be double-quoted, and that is how to_json would produce it. Your input is a Ruby valid Ruby hash, though.)

Upvotes: 1

Deepak Mahakale
Deepak Mahakale

Reputation: 23671

You can just convert it to symbol and use hash_rocket syntax you will get the expected result

def jsonize(custom_key = "id")
  {
    my_json: {
      custom_key.to_sym => 1,
      name: "John"
    }
  }
end

#=> jsonize('foo')
#=> {
#=>     :my_json => {
#=>          :foo => 1,
#=>         :name => "John"
#=>     }
#=> }

Upvotes: 0

Vladimir Chervanev
Vladimir Chervanev

Reputation: 1652

You can use ":" to separate symbolic keys and values, use "=>" in your example:

def jsonize(custom_key="id")
{
    my_json: {
      "#{custom_key}" => 1,
      name: "John"
    }
  }
end

Upvotes: 1

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