Question

I have a scenario that when I try to access a hash key using a symbol it doesn’t work, but when I access it with a string it works fine. It is my understanding that symbols are recommended over strings, so I am trying to clean my script. I am using hash symbols elsewhere in my script, it is just this specific scenario that does not work.

Here is the snippet:

account_params ={}
File.open('file', 'r') do |f|
  f.each_line do |line|
    hkey, hvalue = line.chomp.split("=")
    account_params[hkey] = hvalue
  end
end

account_scope = account_params["scope"]

This works, however if I use a symbol it doesn’t, as shown below:

account_scope = account_params[:scope]

When I use a symbol I get:

can't convert nil into String (TypeError)

I am not sure if it matters, but the contents of this specific hash value looks something like this:

12345/ABCD123/12345

Answer 1

The key you’re reading in from the file is a string. In fact, everything you’re reading in from the file is a string. If you want the keys in your hash to be symbols, you could update the script the do this instead:

account_params[hkey.to_sym] = hvalue

This will turn “hkey” into a symbol instead of using the string value.

Ruby provides a variety of these types of methods which will coerce the value into a different type. For instance: to_i will take it to an integer, to_f to a float, and to_s will take something back to a string value.