Calling OptionParser inside a Rake Task

Question

Given the dummy rake task below

require "optparse" namespace :a do namespace :b do task c: :environment do options = {} OptionParser.new do |parser| parser.banner = "" parser.on("-v", "--verbose", "Run verbosely") do |v| options[:verbose] = v end end.parse! puts "options: #{options}" end end end

How should I call it?

From my understanding, the way should be bin/rails a:b:c -v 3 or bin/rails a:b:c -- -v 3

But both ways generate:

Unrecognized command "3" (Rails::Command::UnrecognizedCommandError)

What am I missing here?

I'm running the task on a Mac.

UPDATE 1

a@mac appa % bundle exec rake a:b:c -- -v 3 options: {} rake aborted! Don't know how to build task '3' (See the list of available tasks with `rake --tasks`) /Users/sa/.rbenv/versions/3.3.7/bin/bundle:25:in `load' /Users/sa/.rbenv/versions/3.3.7/bin/bundle:25:in `<main>' (See full trace by running task with --trace)

Never used OptionParser in Rake tasks within Rails, maybe bin/rails is already interpreting the options? It might be easier to create a Thor task though which provides these kind of option passing out of the box. — Stefan
– Stefan, Commented Apr 24 at 10:49
This blog post is from 2023 but still seems pretty useful: Tips for writing Rails tasks with Thor instead of Rake — Stefan
– Stefan, Commented Apr 24 at 10:52

engineersmnky · Accepted Answer · 2025-04-24 20:22:34Z

You can capture the arguments sent to a Rake task as a block variable.

It is unclear what you intended the 3 to do but it appears that the following works fine:

require "optparse" namespace :a do namespace :b do task c: :environment do |_,args| #_ is the task name options = {} OptionParser.new do |parser| parser.banner = "" parser.on("-v", "--verbose", "Run verbosely") do |v| options[:verbose] = v end parser.on("-n", "--number [NUM]",Integer, "Some Number") do |n| options[:number] = n end end.parse!(args.to_a) #pass the collected arguments to OptionParser#parse! puts "options: #{options}" end end end

Called as

bundle exec rake a:b:c[--verbose,-n3] #=> options: {:verbose=>true, :number=>3} bin/rails a:b:c[-v,--number,7] #=> options: {:verbose=>true, :number=>7} bin/rails a:b:c[-v,3] #=> options: {:verbose=>true}

As an aside if every option just needs to be converted into a Hash you can use:

require "optparse" namespace :a do namespace :b do task c: :environment do |_,args| #_ is the task name options = {} OptionParser.new do |parser| parser.banner = "" parser.on("-v", "--verbose", "Run verbosely") parser.on("-n", "--number [NUM]",Integer, "Some Number") end.parse!(args.to_a, into: options) puts "options: #{options}" end end end

Ronak Bhatt · Accepted Answer · 2025-04-24 13:06:12Z

✅ How to call a Rake task with OptionParser

# lib/tasks/test_optparse.rake require "optparse" namespace :a do namespace :b do task c: :environment do options = {} OptionParser.new do |parser| parser.banner = "Usage: rake a:b:c [options]" parser.on("-v", "--verbose", "Run verbosely") do |v| options[:verbose] = v end end.parse! puts "options: #{options.inspect}" end end end

🧪 How to call it correctly

Use the rake command (not rails) and add -- before the options:

bundle exec rake a:b:c -- -v //OR rake a:b:c -- -v

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