How to pass command line arguments to a rake task

Question

I have a rake task that needs to insert a value into multiple databases.

I'd like to pass this value into the rake task from the command line, or from another rake task.

How can I do this?

Answer 1

While passing parameters, it is better option is an input file, can this be a excel a json or whatever you need and from there read the data structure and variables you need from that including the variable name as is the need. To read a file can have the following structure.

  namespace :name_sapace_task do
    desc "Description task...."
      task :name_task  => :environment do
        data =  ActiveSupport::JSON.decode(File.read(Rails.root+"public/file.json")) if defined?(data)
    # and work whit yoour data, example is data["user_id"]

    end
  end

Example json

{
  "name_task": "I'm a task",
  "user_id": 389,
  "users_assigned": [389,672,524],
  "task_id": 3
}

Execution

rake :name_task 

Answer 2

The ways to pass argument are correct in above answer. However to run rake task with arguments, there is a small technicality involved in newer version of rails

It will work with rake "namespace:taskname['argument1']"

Note the Inverted quotes in running the task from command line.

Answer 3

If you can't be bothered to remember what argument position is for what and you want do something like a ruby argument hash. You can use one argument to pass in a string and then regex that string into an options hash.

namespace :dummy_data do
  desc "Tests options hash like arguments"
  task :test, [:options] => :environment do |t, args|
    arg_options = args[:options] || '' # nil catch incase no options are provided
    two_d_array = arg_options.scan(/\W*(\w*): (\w*)\W*/)
    puts two_d_array.to_s + ' # options are regexed into a 2d array'
    string_key_hash = two_d_array.to_h
    puts string_key_hash.to_s + ' # options are in a hash with keys as strings'
    options = two_d_array.map {|p| [p[0].to_sym, p[1]]}.to_h
    puts options.to_s + ' # options are in a hash with symbols'
    default_options = {users: '50', friends: '25', colour: 'red', name: 'tom'}
    options = default_options.merge(options)
    puts options.to_s + ' # default option values are merged into options'
  end
end

And on the command line you get.

$ rake dummy_data:test["users: 100 friends: 50 colour: red"]
[["users", "100"], ["friends", "50"], ["colour", "red"]] # options are regexed into a 2d array
{"users"=>"100", "friends"=>"50", "colour"=>"red"} # options are in a hash with keys as strings
{:users=>"100", :friends=>"50", :colour=>"red"} # options are in a hash with symbols
{:users=>"100", :friends=>"50", :colour=>"red", :name=>"tom"} # default option values are merged into options

Answer 4

Another commonly used option is to pass environment variables. In your code you read them via ENV['VAR'], and can pass them right before the rake command, like

$ VAR=foo rake mytask

Answer 5

To pass arguments to the default task, you can do something like this. For example, say "version" is your argument:

task :default, [:version] => [:build]

task :build, :version do |t,args|
  version = args[:version]
  puts version ? "version is #{version}" : "no version passed"
end

Then you can call it like so:

$ rake
no version passed

or

$ rake default[3.2.1]
version is 3.2.1

or

$ rake build[3.2.1]
version is 3.2.1

However, I have not found a way to avoid specifying the task name (default or build) while passing in arguments. Would love to hear if anyone knows of a way.

Answer 6

Most of the methods described above did not work for me, maybe they are deprecated in the newer versions. The up-to-date guide can be found here: http://guides.rubyonrails.org/command_line.html#custom-rake-tasks

a copy-and-paste ans from the guide is here:

task :task_name, [:arg_1] => [:pre_1, :pre_2] do |t, args|
  # You can use args from here
end

Invoke it like this

bin/rake "task_name[value 1]" # entire argument string should be quoted