How to read/write a hash from a file in ruby? [closed] - ruby

Question

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 2 years ago.
Improve this question
I want to store data of countries in a file and read that data. I tried to write it in filename.yml file but I am not able to get each hash separately to perform specific operation. Have a look what I tried
require 'yaml'
def addData
puts 'Enter country name :'
name = gets.chop.to_s
puts 'Enter population in billion :'
population = gets.chop.to_s
puts 'Enter GDP in lakh crore USD:'
gdp = gets.chop.to_s
puts 'Enter army strength:'
army_strength = gets.chop.to_s
puts 'Enter state of country:'
state = gets.chop.to_s
country = Hash.new
country = { "name" => name , "population" => population , "gdp" => gdp , "army_strength" => army_strength , "state" => state }
arr_country.push(country)
# Writing to the file
File.open('filename.yml','a') { |f| YAML.dump(country, f) }
end
def readData
File.open('filename.yml') {
|f|.each {
arr = YAML.load(f)
if arr
puts arr
puts arr.class
end
}
}
end
while true
puts '1. Write','2. Read','3.Exit'
opt = gets.chop.to_i
if (opt>2)
return
end
case opt
when 1
addData
when 2
readData
end
end
But it's not working, what would be the best way ?

Answer 1

Apart from the minor mistakes, that are mentioned above, you might have most success using the load_stream function from YAML, rather than load
def readData
File.open('filename.yml') do |f|
arr = YAML.load_stream(f)
if arr
puts arr
puts arr.class
end
end
end
While this is not how I would do it, it will allow you to append to the file, from any source, as long as it remains compatible with YAML.
My preference would be to use a database.
the resulting full code, on my system (run through rubocop) is:
require 'yaml'
def add_data
puts 'Enter country name :'
name = gets.chop.to_s
puts 'Enter population in billion :'
population = gets.chop.to_s
puts 'Enter GDP in lakh crore USD:'
gdp = gets.chop.to_s
puts 'Enter army strength:'
army_strength = gets.chop.to_s
puts 'Enter state of country:'
state = gets.chop.to_s
country = {}
country = { 'name' => name, 'population' => population, 'gdp' => gdp, 'army_strength' => army_strength, 'state' => state }
# Writing to the file
File.open('filename.yml', 'a') { |f| YAML.dump(country, f) }
end
def read_data
arr = []
File.open('filename.yml') do |f|
arr = YAML.load_stream(f)
end
return unless arr
puts arr
puts arr.class
end
loop do
puts '1. Write', '2. Read', '3.Exit'
opt = gets.chop.to_i
break if opt > 2
case opt
when 1
add_data
when 2
read_data
end
end

Answer 2

The f.each does not make sense. f is the file object, and each processes each line and tries to interpret each line as a separate YAML expression. However, your whole file consists of a single YAML expression.
You could do something like:
country = YAML.load(File.read('filename.yaml'))