Add Look Up Time Zone Info For Identifier 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).
 
-_1418 TILs and counting..._
+_1419 TILs and counting..._
 
 ---
 
@@ -905,6 +905,7 @@ _1418 TILs and counting..._
 - [Load A File When Starting Rails Console](rails/load-a-file-when-starting-rails-console.md)
 - [Load Records In Batches With find_each](rails/load-records-in-batches-with-find-each.md)
 - [Log SQL Queries Executed By ActiveRecord](rails/log-sql-queries-executed-by-activerecord.md)
+- [Look Up Time Zone Info For Identifier](rails/look-up-time-zone-info-for-identifier.md)
 - [Mark A Migration As Irreversible](rails/mark-a-migration-as-irreversible.md)
 - [Make A String Attribute Easy To Inquire About](rails/make-a-string-attribute-easy-to-inquire-about.md)
 - [Make ActionMailer Synchronous In Test](rails/make-action-mailer-synchronous-in-test.md)

rails/look-up-time-zone-info-for-identifier.md

@@ -0,0 +1,33 @@
+# Look Up Time Zone Info For Identifier
+
+The `ActiveSupport::TimeZone` class overrides the `#[]` method to be a lookup
+mechanism for IANA Time Zone Identifier strings. These are strings like
+`America/Chicago` (or anything else listed under `TZInfo::Timezone.all`).
+
+Let's get an instance for `America/Chicago`.
+
+```ruby
+> chi = ActiveSupport::TimeZone['America/Chicago']
+=> #<ActiveSupport::TimeZone:0x00000001099d8140
+ @name="America/Chicago",
+ @tzinfo=#<TZInfo::DataTimezone: America/Chicago>,
+ @utc_offset=nil>
+```
+
+Notice it has a `tzinfo` instance variable that we can access. That object
+contains all kinds of useful things.
+
+```ruby
+> chi.tzinfo.name
+=> "America/Chicago"
+> chi.tzinfo.friendly_identifier
+=> "America - Chicago"
+> chi.tzinfo.abbr
+=> "CDT"
+> chi.tzinfo.utc_offset
+=> -18000
+> chi.tzinfo.dst?
+=> true
+```
+
+All of these and more. Run `ls chi.tzinfo` in a `pry` session to see what else.