Add Handle Named Arguments In A Rake Task as a Rails til

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1152 TILs and counting..._
+_1153 TILs and counting..._
 
 ---
 
@@ -702,6 +702,7 @@ _1152 TILs and counting..._
 - [Get An Empty ActiveRecord Relation](rails/get-an-empty-activerecord-relation.md)
 - [Get The Column Names For A Model](rails/get-the-column-names-for-a-model.md)
 - [Get The Current Time](rails/get-the-current-time.md)
+- [Handle Named Arguments In A Rake Task](rails/handle-named-arguments-in-a-rake-task.md)
 - [Hash Slicing](rails/hash-slicing.md)
 - [Ignore Poltergeist JavaScript Errors](rails/ignore-poltergeist-javascript-errors.md)
 - [Include Devise Helpers In Your Controller Tests](rails/include-devise-helpers-in-your-controller-tests.md)

rails/handle-named-arguments-in-a-rake-task.md

@@ -0,0 +1,52 @@
+# Handle Named Arguments In A Rake Task
+
+There are [a number of
+ways](https://www.seancdavis.com/blog/4-ways-to-pass-arguments-to-a-rake-task/)
+to pass arguments into a Rake task. The standard approach only allows for
+positional arguments. When I need named and optional arguments, my preferred
+approach is to use environment variables.
+
+Here is a skimmed down version of a user lookup task. Notice the task
+definition itself doesn't include any arguments. Instead, a couple optional
+values are extracted from the environment (`ENV`) at the beginngin of the task.
+
+```ruby
+desc "An example task with named, optional arguments"
+task :lookup_user => :environment do
+  user_id = ENV['USER_ID']
+  email = ENV['EMAIL']
+
+  if user_id.present?
+    user = User.find(user_id)
+
+    if user.blank?
+      puts "No user for id ##{user_id}"
+    end
+  elsif email.present?
+    user = User.find_by(email: email)
+
+    if user.blank?
+      puts "No user for email #{email}"
+    end
+  end
+
+  puts "User found" if user.present?
+end
+```
+
+This task can be invoked in the following ways:
+
+```bash
+$ rake lookup_user USER_ID=123
+```
+
+```bash
+$ rake lookup_user EMAIL="user@example.com"
+```
+
+or even with both arguments included, in which case the task has been written
+to give precedence to `USER_ID`:
+
+```bash
+$ rake lookup_user EMAIL="user@example.com" USER_ID=123
+```