Add Get ActiveRecord Attribute Directly From Database as a Rails til

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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-_1189 TILs and counting..._
+_1190 TILs and counting..._
 
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@@ -722,6 +722,7 @@ _1189 TILs and counting..._
 - [Find Records With Multiple Associated Records](rails/find-records-with-multiple-associated-records.md)
 - [Force All Users To Sign Out](rails/force-all-users-to-sign-out.md)
 - [Generating And Executing SQL](rails/generating-and-executing-sql.md)
+- [Get ActiveRecord Attribute Directly From Database](rails/get-active-record-attribute-directly-from-database.md)
 - [Get An Array Of Values From The Database](rails/get-an-array-of-values-from-the-database.md)
 - [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)

rails/get-active-record-attribute-directly-from-database.md

@@ -0,0 +1,36 @@
+# Get ActiveRecord Attribute Directly From Database
+
+In Rails, an ActiveRecord model will automatically get methods named after each
+column in the backing database table. This can be called to retrieve those
+values from the respective columns in the database.
+
+What if you wanted to override and alter one of those values? For example,
+ensure the `email` value you're passing around is always fully downcased.
+
+Something like this won't quite work.
+
+```ruby
+def email
+  email.downcase
+end
+```
+
+Because the method is named `email`, the `email` reference inside it will call
+itself, recursively, until it exceeds the stack.
+
+Instead, you need a way of referencing the email attribute that is stored in
+the database.
+[`attribute_in_database`](https://api.rubyonrails.org/classes/ActiveRecord/AttributeMethods/Dirty.html#method-i-attribute_in_database)
+will do the trick.
+
+```ruby
+def email
+  attribute_in_database('email').downcase
+end
+```
+
+That will retrieve the value from the `email` column in the database for this
+record, downcase it, and return it. Anyone calling `email` won't notice the
+difference.
+
+h/t [Dillon Hafer](https://twitter.com/dillonhafer)