method

to_json

v2.3.8 - Show latest stable - 0 notes - Class: Hash

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What's this?

to_json(options = nil) public

Returns a JSON string representing the hash.

Without any options, the returned JSON string will include all the hash keys. For example:

  { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json
  # => {"name": "Konata Izumi", "1": 2, "age": 16}

The keys in the JSON string are unordered due to the nature of hashes.

The :only and :except options can be used to limit the attributes included, and will accept 1 or more hash keys to include/exclude.

  { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:only => [:name, 'age'])
  # => {"name": "Konata Izumi", "age": 16}

  { :name => "Konata Izumi", 'age' => 16, 1 => 2 }.to_json(:except => 1)
  # => {"name": "Konata Izumi", "age": 16}

The options also filter down to any hash values. This is particularly useful for converting hashes containing ActiveRecord objects or any object that responds to options in their to_json method. For example:

  users = User.find(:all)
  { :users => users, :count => users.size }.to_json(:include => :posts)

would pass the :include => :posts option to users, allowing the posts association in the User model to be converted to JSON as well.

Show source

# File activesupport/lib/active_support/json/encoders/hash.rb, line 33
  def to_json(options = nil) #:nodoc:
    hash = as_json(options)

    result = '{'
    result << hash.map do |key, value|
      "#{ActiveSupport::JSON.encode(key.to_s)}:#{ActiveSupport::JSON.encode(value, options)}"
    end * ','
    result << '}'
  end

to_json

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