Add Render An Alternative ActionMailer Template as a Rails til

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://tinyletter.com/jbranchaud).
 
-_984 TILs and counting..._
+_985 TILs and counting..._
 
 ---
 
@@ -636,6 +636,7 @@ _984 TILs and counting..._
 - [Read In Environment-Specific Config Values](rails/read-in-environment-specific-config-values.md)
 - [Read-Only Models](rails/read-only-models.md)
 - [Remove The Default Value On A Column](rails/remove-the-default-value-on-a-column.md)
+- [Render An Alternative ActionMailer Template](rails/render-an-alternative-action-mailer-template.md)
 - [Rescue From](rails/rescue-from.md)
 - [Retrieve An Object If It Exists](rails/retrieve-an-object-if-it-exists.md)
 - [Rounding Numbers With Precision](rails/rounding-numbers-with-precision.md)

rails/render-an-alternative-action-mailer-template.md

@@ -0,0 +1,47 @@
+# Render An Alternative ActionMailer Template
+
+The convention for Rails's ActionMailer is to render the view template that
+corresponds to the mailer class's name and the specific action.
+
+For instance, the `welcome_email` method in the `RegistrationMailer` class will
+correspond to the `app/views/registration_mailer/welcome_email.html.erb` view.
+
+This convention can be overridden. By passing, the `template_name` and
+`template_path` arguments as options to the `mail` method, you can tell the
+mailer to render a different template.
+
+```ruby
+class RegistrationMailer < ActionMailer::Base
+  def welcome_email
+    # mail setup ...
+
+    mail(to: @user.email,
+        subject: 'Welcome!',
+        template_name: 'new_welcome')
+  end
+end
+```
+
+This will look for and use the
+`app/views/registration_mailer/new_welcome.html.erb` template.
+
+Also including the `template_path` option will alter the path to the named
+template:
+
+```ruby
+class RegistrationMailer < ActionMailer::Base
+  def welcome_email
+    # mail setup ...
+
+    mail(to: @user.email,
+        subject: 'Welcome!',
+        template_path: 'v2_mailer_templates',
+        template_name: 'new_welcome')
+  end
+end
+```
+
+This will look for the `app/views/v2_mailer_templates/new_welcome.html.erb`
+template.
+
+[source](https://guides.rubyonrails.org/action_mailer_basics.html#mailer-views)