Add Rollback A Couple Migrations 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).
 
-_1455 TILs and counting..._
+_1458 TILs and counting..._
 
 ---
 
@@ -899,6 +899,7 @@ _1455 TILs and counting..._
 - [Custom Validation Message](rails/custom-validation-message.md)
 - [Customize Paths And Helpers For Devise Routes](rails/customize-paths-and-helpers-for-devise-routes.md)
 - [Customize The Path Of A Resource Route](rails/customize-the-path-of-a-resource-route.md)
+- [Define The Root Path For The App](rails/define-the-root-path-for-the-app.md)
 - [Delete Paranoid Records](rails/delete-paranoid-records.md)
 - [Demodulize A Class Name](rails/demodulize-a-class-name.md)
 - [Different Ways To Add A Foreign Key Reference](rails/different-ways-to-add-a-foreign-key-reference.md)
@@ -964,6 +965,7 @@ _1455 TILs and counting..._
 - [Rescue From With A Separate Method](rails/rescue-from-with-a-separate-method.md)
 - [Respond With JSON Regardless of Content Type](rails/respond-with-json-regardless-of-content-type.md)
 - [Retrieve An Object If It Exists](rails/retrieve-an-object-if-it-exists.md)
+- [Rollback A Couple Migrations](rails/rollback-a-couple-migrations.md)
 - [Rollback A Specific Migration Out Of Order](rails/rollback-a-specific-migration-out-of-order.md)
 - [Rounding Numbers With Precision](rails/rounding-numbers-with-precision.md)
 - [Run A Rake Task Programmatically](rails/run-a-rake-task-programmatically.md)
@@ -1212,6 +1214,7 @@ _1455 TILs and counting..._
 - [Pattern Match Values From A Hash](ruby/pattern-match-values-from-a-hash.md)
 - [Percent Notation](ruby/percent-notation.md)
 - [Precedence Of Logical Operators](ruby/precedence-of-logical-operators.md)
+- [Prevent erb_lint From Removing Opening Tags](ruby/prevent-erb-lint-from-removing-opening-tags.md)
 - [Print Data To Formatted Table](ruby/print-data-to-formatted-table.md)
 - [Question Mark Operator](ruby/question-mark-operator.md)
 - [Rake Only Lists Tasks With Descriptions](ruby/rake-only-lists-tasks-with-descriptions.md)

rails/define-the-root-path-for-the-app.md

@@ -0,0 +1,37 @@
+# Define The Root Path For The App
+
+The `root_path` helper that you might want to use in Rails controllers and
+views is not available by default.
+
+```ruby
+> Rails.application.routes.url_helpers.root_path
+
+ruby/3.2.2/lib/ruby/gems/3.2.0/gems/irb-1.14.0/lib/irb.rb:1285:in `full_message': undefined method `root_path' for #<Module:0x0000000106d11738> (NoMethodError)
+
+Rails.application.routes.url_helpers.root_path
+                                    ^^^^^^^^^^
+Did you mean?  logout_path
+               book_path
+```
+
+It needs to be declared in the `config/routes.rb` file with the controller
+action that it points to.
+
+```ruby
+# config/routes.rb
+Rails.application.routes.draw do
+  root 'home#index'
+end
+```
+
+Once this is defined the `root_path` will now be available with the rest of
+your URL helpers.
+
+```ruby
+better-reads(dev)> reload!
+Reloading...
+better-reads(dev)> Rails.application.routes.url_helpers.root_path
+=> "/"
+```
+
+[source](https://guides.rubyonrails.org/routing.html#using-root)

rails/rollback-a-couple-migrations.md

@@ -0,0 +1,25 @@
+# Rollback A Couple Migrations
+
+Let's say we need to rollback a couple Rails migrations that have been applied
+to our local environment. We run `rails db:migrate:status` and see that there
+are _2_ migrations that we want to _undo_.
+
+We can accomplish this by using the `STEP` env var with the rollback command.
+
+```bash
+$ rails db:rollback STEP=2
+```
+
+Just set `STEP` to the number of migrations that we need to rollback. If we
+then rerun `rails db:migrate:status` we'll now see those latest two migrations
+are `down`.
+
+Note: by default Rails doesn't like to operate with pending migrations. If we
+want to temporarily disable the pending migration check, we can alter the
+migration error config in `config/development.rb`.
+
+```diff
+  # Raise an error on page load if there are pending migrations.
+-  # config.active_record.migration_error = :page_load
++  config.active_record.migration_error = false
+```

ruby/prevent-erb-lint-from-removing-opening-tags.md

@@ -0,0 +1,45 @@
+# Prevent erb_lint From Removing Opening Tags
+
+The [`erb_lint` gem](https://github.com/Shopify/erb_lint) is a tool from
+shopify for linting and auto-formatting ERB files. When I first set it up in a
+Rails codebase with the base `.erb-lint.yml` recommended in the README, I ran
+into a pernicious issue. The linter wanted to remove opening tags (i.e. `<%`
+and `<%=`) from my ERB files.
+
+So, for a file that looked like this:
+
+```erb
+<div>
+  <%= form_with(url: login_path, scope: :session) do |f| %>
+    <div>
+      <%= f.label :email %>
+      <%= f.email_field :email %>
+    </div>
+</div>
+```
+
+It would get formatted to this:
+
+```erb
+<div>
+form_with(url: login_path, scope: :session) do |f| %>
+    <div>
+f.label :email %>
+f.email_field :email %>
+    </div>
+</div>
+```
+
+Yikes!
+
+I had to disable a couple rules (under `rubocop_config:`) in the `.erb-lint.yml` file to get it to stop
+doing this.
+
+```yaml
+Layout/InitialIndentation:
+  Enabled: false
+Layout/TrailingEmptyLines:
+  Enabled: false
+```
+
+[source](https://github.com/Shopify/erb_lint/issues/222)