I want to ask for user input, but I only want to do it once (possibly save the information within the program), meaning, something like this:
print "Enter your name (you will only need to do this once): "
name = gets.chomp
str = "Hello there #{name}" #<= As long as the user has put their name in the very first
# time the program was run, I want them to never have to put thier name in again
How can I got about doing this within a Ruby program?
This program will be run by multiple users throughout the day on multiple systems. I've attempted to store it into memory, but obviously that failed because from my understand that memory is wiped everytime a Ruby program stops executing.
My attempts:
def capture_user
print 'Enter your name: '
name = gets.chomp
end
#<= works but user has to put in name multiple times
def capture_name
if File.read('name.txt') == ''
print "\e[36mEnter name to appear on email (you will only have to do this once):\e[0m "
@esd_user = gets.chomp
File.open('name.txt', 'w') { |s| s.puts(@esd_user) }
else
@esd_user = File.read('name.txt')
end
end
#<= works but there has to be a better way to do this?
require 'tempfile'
def capture_name
file = Tempfile.new('user')
if File.read(file) == ''
print "\e[36mEnter name to appear on email (you will only have to do this once):\e[0m "
@esd_user = gets.chomp
File.open(file, 'w') { |s| s.puts(@esd_user) }
else
@esd_user = File.read(file)
end
end
#<= Also used a tempfile, this is a little bit over kill I think,
# and doesn't really help because the users can't access their Appdata
You will want to store the username in a file on the local file system. Ruby provides many ways to do this, and we'll explore one in this answer: YAML files.
YAML files are a structured storage file that can store all kinds of different data, and is a good place to store config data. In fact, YAML configuration files are key parts of the largest Ruby projects in existence. YAML gives you a good starting point for supporting future configuration needs, beyond the current one, which is a great way to plan feature development.
So, how does it work? Let's take a look at your requirement using a YAML config:
require 'yaml'
config_filename = "config.yml"
config = {}
name = nil
if file_exists(config_filename)
begin
config = YAML.load_file(config_filename)
name = config["name"]
rescue ArgumentError => e
puts "Unable to parse the YAML config file."
puts "Would you like to proceed?"
proceed = gets.chomp
# Allow the user to type things like "N", "n", "No", "nay", "nyet", etc to abort
if proceed.length > 0 && proceed[0].upcase == "N"
abort "User chose not to proceed. Aborting!"
end
end
end
if name.nil? || (name.strip.length == 0)
print "Enter your name (you will only need to do this once): "
name = gets.chomp
# Store the name in the config (in memory)
config["name"] = name
# Convert config hash to a YAML config string
yaml_string = config.to_yaml
# Save the YAML config string to the config file
File.open(config_filename, "w") do |out|
YAML.dump(config, out)
end
end
Rather than show you the bare minimum to meet your needs, this code includes a little error handling and some simple safety checks on the config file. It may well be robust enough for you to use immediately.
The very first bit simply requires the YAML standard library. This makes the YAML functions work in your program. If you have a loader file or some other common mechanism like that, simply place the require 'yaml' there.
After that, we initialize some variables that get used in this process. You should note that the config_filename has no path information in it, so it will be read from the current directory. You will likely want to store the config file in a common place, such as in ~/.my-program-name/config.yml or C:\Documents and Settings\MyUserName\Application Data\MyProgramName\. This can be done pretty easily, and there's plenty to help, such as this Location to Put User Config Files in Windows and Location of ini/config files in linux/unix.
Next, we check to see if the file actually exists, and if so, we attempt to read the YAML contents from it. The YAML.load_file() method handles all the heavy lifting here, so you just have to ask the config hash that's returned for the key that you're interested in, in this case, the "name" key.
If an error occurs while reading the YAML file, it indicates that the file might possibly be corrupted, so we try to deal with that. YAML files are easy to edit by hand, but when you do that, you can also easily introduce an error that will make loading the YAML file fail. The error handling code here will allow the user to abort the program and go back to fix the YAML file, so that it doesn't simply get overwritten.
After that, we try to see if we've been had a valid name from the YAML config, and if not, we go ahead and accept it from the user. Once they've entered a name, we add it to the config hash, convert the hash to a YAML-formatted string, and then write that string to the config file.
And that's all it takes. Just about anything that you can store in a Ruby hash, you can store in a YAML file. That's a lot of power for storing config information, and if you later need to add more config options, you have a versatile container that you can use exactly for that purpose.
If you want to do any further reading on YAML, you can find some good information here:
While some of these articles are a bit older, they're still very relevant and will give you a jumping off point for further reading. Enjoy!