Access Rake Task Description from Within Task

Access Rake Task Description from within Task

taskmust be defined as a parameter for the task-block.

desc "Populate DB"
task :populate do |task|
  puts task.comment # "Populate DB"
  puts task.full_comment # "Populate DB"
  puts task.name # "populate "
end

Edit:
This solution works with rake 0.8.7. At least rake 0.9.2.2 need an additional Rake::TaskManager.record_task_metadata = true (I checked only this two versions).

A stand alone ruby-script with adaption:

gem 'rake'    #'= 0.9.2.2'
require 'rake'

#Needed for rake/gem '= 0.9.2.2'
Rake::TaskManager.record_task_metadata = true

desc "Populate DB"
task :populate do |task|
  p task.comment # "Populate DB"
  p task.full_comment # "Populate DB"
  p task.name # "populate "
end

if $0 == __FILE__
  Rake.application['populate'].invoke()  #all tasks
end

Reason: in rake/task_manager.rb line 30 (rake 0.9.2.2) is a check

  if Rake::TaskManager.record_task_metadata
    add_location(task)
    task.add_description(get_description(task))
  end

The default false is set in line 305.

How do I programmatically extract a rake task's description?

Use the methods comment or full_comment for that. More docs on the Rake::Task class here.

How to access namespace from within a rake task?

task.name includes the namespace. Use this tip to get task.name to print under rake 0.9.2.2.

Can a Rake task be documented with a multiline usage accessible from command line?

I came here with the same problem: I added a parameter with a default value to task, and wanted to document that in enough detail to make sure that folks knew they could pass their own value.

I found that if I made the string longer, it would print the entire string, wrapping it to the next line, which looks terrible. But if I passed a multiline string, the -T output would only print the string up to the end of the first line.

It turns out, this behavior is intentional:

https://ruby.github.io/rake/Rake/DSL.html#method-i-desc

Descriptions are shown with rake -T (up to the first sentence)
and rake -D (the entire description).

Given your example above, rake -D (or rake --describe) should do the trick:

$ rake -T
rake idle[option,token]                # Do nothing, even when arguments are provided

$ rake -D
rake idle[option,token]
    Do nothing, even when arguments are provided.
    Usage:
      rake 'users:idle["something", "anotherthing"]'
      rake 'users:idle[, "anotherthing"]' # something is ignored anyway
      rake users:idle # do nothing tersely

Accessing rake task variables in controller and Scheduling rake tasks

First thing, calling rake task from controller is a bad practice. Ryan published that video at 2008 since that many better solution have came up. You shouldn't ignore it.

I suggest you to use delayed_job, it serves your needs in a great way. Since, if you want to invoke task dynamically, there should be some checker which will continuously check the desire field every second. Delayed job keep checking its database every time, you can use that.

Anyway,You can use something like this

def self.run_when
  Scheduler.all.each do |s|
    if d.dynamically_assigned_field < 1.second.ago
       d.run_my_job!
       d.status = "finished"
       d.save
    end
  end
end 

And, in model you can do something like this

 def run_my_job!
   self.status = "processing"
   self.save
   long_running_task
 end

One thing also you should keep in mind that if too many workers/batch/cron job starts at run at same it will fight for resources and may enter into deadlock state. As per your server capacity, you should limit the running jobs.

Sidekiq is also a good option you can consider. Personally, i like sidekiq because it doesn't hit my database everytime , scales very effectively. It uses redis but it is expensive.

Rails Rake Task - Access to model class

You're close :)

#lib/tasks/defaultuser.rake
require 'rake'
namespace :defaultuser do
  task :adduser => :environment do
    ...
  end

Note the use of :environment, which sets up the necessary Rails environment prior to calling the rake task. After that, your User object will be in scope.

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