Ruby - Thor execute a specific Task first

Question

Is it possible to call a specific task first, when i run a thor task?

my Thorfile:

class Db < Thor

  desc "show_Version", "some description ..."
  def show_version # <= needs a database connection
    puts ActiveRecord::Migrator.current_version
  end

  private

  def connect_to_database # <= call this always when a task from this file is executed
    # connect here to database
  end

end

I could write the "connect_to_database" method in every task but that seems not very DRY.

Answer 1

You can use invoke to run other tasks:

def show_version
  invoke :connect_to_database
  # ...
end

That will also make sure that they are run only once, otherwise you can just call the method as usual, e.g.

def show_version
  connect_to_database
  # ...
end

Or you could add the call to the constructor, to have it run first in every invocation:

def initialize(*args)
  super
  connecto_to_database
end

The call to super is very important, without it Thor will have no idea what to do.

Answer 2

A rather under-documented feature of thor is the method default_task. Passed a symbol from within your thor script, you can set it to run a specific task and, using invoke, run other tasks.

For example:

default_task :connect_to_database