Task to read, write and save a JSON file in Ruby

read_write_json_file.rake

namespace :json do

	# Usage: rake json:set_fields[file_name]
	desc "Set some sample fields to an existing JSON file"
	task :set_fields, [:file_name] => :environment do |t, args|
		file_name = args[:file_name]
		file_folder  = Rails.root.join('app','assets','sample') 		# Step over the right folder
		file = File.read(file_folder.join(file_name + ".json"))		 	# Get the JSON file
		fields = JSON.parse(form)						# Get the JSON data to parse
		updated_fields = set_fields(fields)					# Set required to ruby Hash

		File.open(file_folder.join(form_name + ".json"), "w") do |f|            # Open the file to write
			f.puts JSON.pretty_generate(updated_fields)                     # Write the updated JSON
		end	
	end
	
	def set_fields(fields)			
		fields.each do |field|
			field["somekey"]["someproperty"] = true
		end
	fields
	end
end