Add Check If ActiveRecord Update Fails as a rails til

Author: jbranchaud

README.md

@@ -9,7 +9,7 @@ and pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://tinyletter.com/jbranchaud).
 
-_930 TILs and counting..._
+_931 TILs and counting..._
 
 ---
 
@@ -558,6 +558,7 @@ _930 TILs and counting..._
 - [Capybara Page Status Code](rails/capybara-page-status-code.md)
 - [Cast Common Boolean-Like Values To Booleans](rails/cast-common-boolean-like-values-to-booleans.md)
 - [Change The Nullability Of A Column](rails/change-the-nullability-of-a-column.md)
+- [Check If ActiveRecord Update Fails](rails/check-if-activerecord-update-fails.md)
 - [Check Specific Attributes On ActiveRecord Array](rails/check-specific-attributes-on-activerecord-array.md)
 - [Code Statistics For An Application](rails/code-statistics-for-an-application.md)
 - [Comparing DateTimes Down To Second Precision](rails/comparing-datetimes-down-to-second-precision.md)

rails/check-if-activerecord-update-fails.md

@@ -0,0 +1,33 @@
+# Check If ActiveRecord Update Fails
+
+There are two ways to update an `ActiveRecord` instance (not to mention
+[`assign_attributes`](https://api.rubyonrails.org/classes/ActiveModel/AttributeAssignment.html),
+[`update_attribute`](https://api.rubyonrails.org/classes/ActiveRecord/Persistence.html#method-i-update_attribute),
+etc.).
+
+You can call
+[`update`](https://api.rubyonrails.org/classes/ActiveRecord/Persistence.html#method-i-update)
+and
+[`update!`](https://api.rubyonrails.org/classes/ActiveRecord/Persistence.html#method-i-update-21).
+If the updates would make the record invalid based on the model's validations,
+then the update will fail.
+
+You can tell if `update` failed because it will return `false` (instead of
+`true`).
+
+```ruby
+unless book.update(book_params)
+  log_book_update_failed(id: book.id)
+end
+```
+
+The `update!` version will raise an `ActiveRecord::ActiveRecordError`
+exception if the update fails.
+
+```ruby
+begin
+  book.update!(book_params)
+rescue ActiveRecord::ActiveRecordError
+  log_book_update_failed(id: book.id)
+end
+```