Logic to test whether a command line argument to a rails rake task is present?

Question

I have a rake task that returns a count of records for a given email. The email is provided to the rake task as a command line argument, like so

rake stats:count email=me@gmail.com

But if the rake task is called without an email provided (ie rake stats:count ), I would like helpful message to appear, like "Please provide an email"

How do I do this?

I have tried this

email = ENV['email']
if email.nil? puts "Please provide an email"
end

But it errors with NameError: undefined local variable or method email' for main:Object

Answer 1

An argument provided to a rake task via var=value is accessible inside the rake task with ENV['var'] .

If the argument is not provided, ENV['var'] will return nil .

So you can simply check ENV['email'].nil?

ie

if ENV['email'].nil?
  puts "Please provide an email" 
else
  # code to run if email is provided
end