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

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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    gt   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

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I couldn t figure out how to pass args and also the  environment until I worked this out   namespace  db do   desc  Export product data    task  export    file token   file path    gt   environment do  t  args      args with defaults  file token   gt   products    file path   gt     lib data             do stuff          end end   And then I call like this   rake db export  foo   tmp

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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    gt   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   gt  100    friends   gt  50    colour   gt  red     options are in a hash with keys as strings   users  gt  100    friends  gt  50    colour  gt  red     options are in a hash with symbols   users  gt  100    friends  gt  50    colour  gt  red    name  gt  tom     default option values are merged into options

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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

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

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To run rake tasks with traditional arguments style   rake task arg1 arg2   And then use   task  task do     args    puts  This is argument 1    args first   end   Add following patch of rake gem   Rake  Application class eval do    alias origin top level top level    def top level      top level tasks    top level tasks join           origin top level   end    def parse task string string     nodoc      parts   string split         return parts shift  parts   end  end  Rake  Task class eval do    def invoke  args      invoke with call chain args  Rake  InvocationChain  EMPTY    end  end

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In addition to answer by kch  I didn t find how to leave a comment to that  sorry    You don t have to specify variables as ENV variables before the rake command  You can just set them as usual command line parameters like that   rake mytask var foo   and access those from your rake file as ENV variables like such   p ENV  var       gt   foo

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You can specify formal arguments in rake by adding symbol arguments to the task call   For example   require  rake   task  my task    arg1   arg2  do  t  args    puts  Args were    args  of class   args class     puts  arg1 was     args  arg1    of class   args  arg1  class     puts  arg2 was     args  arg2    of class   args  arg2  class   end  task  invoke my task do   Rake application invoke task  my task 1  2    end    or if you prefer this syntax    task  invoke my task 2 do   Rake  Task  my task  invoke 3  4  end    a task with prerequisites passes its    arguments to it prerequisites task  with prerequisite    arg1   arg2    gt   my task   lt - name of prerequisite task    to specify default values     we take advantage of args being a Rake  TaskArguments object task  with defaults   arg1   arg2 do  t  args    args with defaults  arg1   gt   default 1   arg2   gt   default 2    puts  Args with defaults were    args   end   Then  from the command line      rake my task 1 false  Args were    arg1   1    arg2   false   of class Rake  TaskArguments arg1 was   1  of class String arg2 was   false  of class String    rake  my task 1  2   Args were    arg1   1    arg2   2      rake invoke my task Args were    arg1   1    arg2   2      rake invoke my task 2 Args were    arg1  3   arg2  4     rake with prerequisite 5 6  Args were    arg1   5    arg2   6      rake with defaults Args with defaults were    arg1   default 1   arg2   default 2     rake with defaults  x   y   Args with defaults were    arg1   x    arg2   y     As demonstrated in the second example  if you want to use spaces  the quotes around the target name are necessary to keep the shell from splitting up the arguments at the space   Looking at the code in rake rb  it appears that rake does not parse task strings to extract arguments for prerequisites  so you can t do task  t1   gt   dep 1 2     The only way to specify different arguments for a prerequisite would be to invoke it explicitly within the dependent task action  as in  invoke my task and  invoke my task 2   Note that some shells  like zsh  require you to escape the brackets  rake my task   arg1

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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

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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    gt    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

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I just wanted to be able to run     rake some task arg1 arg2   Simple  right   Nope    Rake interprets arg1 and arg2 as tasks  and tries to run them  So we just abort before it does   namespace  some do   task task   environment do     arg1  arg2   ARGV        your task         exit   end end   Take that  brackets   Disclaimer  I wanted to be able to do this in a pretty small pet project  Not intended for  real world  usage since you lose the ability to chain rake tasks  i e  rake task1 task2 task3   IMO not worth it  Just use the ugly rake task arg1 arg2

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Options and dependencies need to be inside arrays  namespace  thing do   desc  quot it does a thing quot    task  work    option   foo   bar  do  task  args      puts  quot work quot   args   end      task  another    option   foo   bar  do  task  args      puts  quot another   args  quot      Rake  Task  quot thing work quot   invoke args  option   args  foo   args  bar         or splat the args       Rake  Task  quot thing work quot   invoke  args    end  end  Then rake thing work 1 2 3    gt  work    option  gt  quot 1 quot    foo  gt  quot 2 quot    bar  gt  quot 3 quot    rake thing another 1 2 3    gt  another   option  gt  quot 1 quot    foo  gt  quot 2 quot    bar  gt  quot 3 quot     gt  work    option  gt  quot 1 quot    foo  gt  quot 2 quot    bar  gt  quot 3 quot     NOTE  variable task is the task object  not very helpful unless you know care about Rake internals   RAILS NOTE   If running the task from Rails  it s best to preload the environment by adding   gt    environment  which is a way to setup dependent tasks     task  work    option   foo   bar    gt    environment  do  task  args      puts  quot work quot   args   end

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If you want to pass named arguments  e g  with standard OptionParser  you could use something like this     rake user create -- --user test example com --pass 123   note the --  that s necessary for bypassing standard Rake arguments  Should work with Rake 0 9 x   lt   10 3 x   Newer Rake has changed its parsing of --  and now you have to make sure it s not passed to the OptionParser parse method  for example with parser parse  ARGV 2  -1    require  rake  require  optparse    Rake task for creating an account  namespace  user do  args    desc  Creates user account with given credentials  rake user create      environment is required to have access to Rails models   task  create do     options          OptionParser new args  do  opts        opts banner    Usage  rake user create  options         opts on  -u    --user  username    User s email address   String  do  user          options  user    user       end       opts on  -p    --pass  password    User s password   String  do  pass          options  pass    pass       end     end parse       puts  creating user account         u   Hash new     u  email    options  user      u  password    options  pass        with some DB layer like ActiveRecord        user   User new u   user save      puts  user      u to s     puts  account created       exit 0   end end   exit at the end will make sure that the extra arguments won t be interpreted as Rake task    Also the shortcut for arguments should work    rake user create -- -u test example com -p 123   When rake scripts look like this  maybe it s time to look for another tool that would allow this just out of box

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I like the  querystring  syntax for argument passing  especially when there are a lot of arguments to be passed    Example   rake  mytask width 10 amp height 20     The  querystring  being   width 10 amp height 20   Warning  note that the syntax is rake  mytask foo bar   and NOT rake mytask  foo bar    When parsed inside the rake task using Rack  Utils parse nested query   we get a Hash     gt    width   gt  10    height   gt  20      The cool thing is that you can pass hashes and arrays  more below   This is how to achieve this   require  rack utils   task  mytask   args expr do  t args    args with defaults  args expr   gt   width 10 amp height 10     options   Rack  Utils parse nested query args  args expr   end   Here s a more extended example that I m using with Rails in my delayed job active record threaded gem   bundle exec rake  dj start ebooks workers number  16 amp ebooks worker timeout  60 amp albums workers number  32 amp albums worker timeout  120     Parsed the same way as above  with an environment dependency  in order load the Rails environment   namespace  dj do   task  start     args expr     gt   environment do  t  args        defaults here        options   Rack  Utils parse nested query args  args expr       end end   Gives the following in options    gt    ebooks   gt   workers number   gt  16    worker timeout   gt  60     albums   gt   workers number   gt  32    worker timeout   gt  120

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I ve found the answer from these two websites  Net Maniac and Aimred   You need to have version   0 8 of rake to use this technique  The normal rake task description is this   desc  Task Description  task  task name   gt    depends on taskA   depends on taskB  do    interesting things end   To pass arguments  do three things    Add the argument names after the task name  separated by commas  Put the dependencies at the end using  needs          Place  t  args  after the do    t is the object for this task    To access the arguments in the script  use args arg name  desc  Takes arguments task  task  task name   display value   display times   needs   gt    depends on taskA   depends on taskB  do  t  args    args display times to i times do     puts args display value   end end   To call this task from the command line  pass it the arguments in   s  rake task name  Hello  4    will output  Hello Hello Hello Hello   and if you want to call this task from another task  and pass it arguments  use invoke  task  caller do   puts  In Caller    Rake  Task  task name  invoke  hi  2  end   then the command  rake caller   will output  In Caller hi hi   I haven t found a way to pass arguments as part of a dependency  as the following code breaks   task  caller   gt   task name  hi  2   do    puts  In Caller  end

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Actually  Nick Desjardins answered perfect  But just for education  you can use dirty approach  using ENV argument  task  my task do   myvar   ENV  myvar     puts  myvar    myvar   end   rake my task myvar 10    gt  myvar  10

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One thing I don t see here is how to handle arbitrary arguments  If you pass arguments that are not listed in the task definition  they are still accessible under args extras  task  thing    foo  do  task  args    puts args  foo        named argument   puts args extras      any additional arguments that were passed end

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desc  an updated version  task  task name    arg1   arg2    gt    dependency1   dependency2  do  t  args      puts args  arg1  end

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I use a regular ruby argument in the rake file   DB   ARGV 1    then I stub out the rake tasks at the bottom of the file  since rake will look for a task based on that argument name    task  database name1 task  database name2   command line   rake mytask db name   this feels cleaner to me than the var foo ENV var and the task args blah  blah2  solutions  the stub is a little jenky  but not too bad if you just have a few environments that are a one-time setup

[ruby] How to pass command line arguments to a rake task

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