Add Remove Blank Values From A Hash as a Rails TIL

README.md

@@ -10,7 +10,7 @@ working across different projects via [VisualMode](https://www.visualmode.dev/).
 
 For a steady stream of TILs, [sign up for my newsletter](https://visualmode.kit.com/newsletter).
 
-_1851 TILs and counting..._
+_1852 TILs and counting..._
 
 See some of the other learning resources I work on:
 
@@ -1260,6 +1260,7 @@ If you've learned something here, support my efforts writing daily TILs by
 - [Read-Only Models](rails/read-only-models.md)
 - [Rebuild Tailwind Bundle For Dev Server](rails/rebuild-tailwind-bundle-for-dev-server.md)
 - [Remove A Database Column From A Table](rails/remove-a-database-column-from-a-table.md)
+- [Remove Blank Values From A Hash](rails/remove-blank-values-from-a-hash.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)
 - [Render The Response Body In Controller Specs](rails/render-the-response-body-in-controller-specs.md)

rails/remove-blank-values-from-a-hash.md

@@ -0,0 +1,51 @@
+# Remove Blank Values From A Hash
+
+Ruby's [`Enumerable`](https://docs.ruby-lang.org/en/master/Enumerable.html) has
+a method `#compact` that will remove `nil` values from `Enumerable` objects like
+hashes and arrays.
+
+```ruby
+> { one: nil, two: 2, three: "" }.compact
+=> {two: 2, three: ""}
+> [nil, 2, ""].compact
+=> [2, ""]
+```
+
+That is often what I want because I'm thinking in terms of values being either
+`nil` or valid value.
+
+Sometimes I want to remove all _blank_ values, not just the `nil` ones. This
+happens in a Rails context like in a controller when dealing with parameters
+from a request -- a form field was left blank (`""`) or no options were picked
+from the multi-select (`[]`).
+
+Rails adds
+[`#compact_blank`](https://api.rubyonrails.org/classes/Enumerable.html#method-i-compact_blank)
+to `Enumerable` to support these cases. Consider that `#compact` corresponds to
+`#nil?` where as `#compact_blank` corresponds to `#blank?`.
+
+Here is the example hash pulled from the docs:
+
+```ruby
+> { a: "", b: 1, c: nil, d: [], e: false, f: true }.compact
+=> {a: "", b: 1, d: [], e: false, f: true}
+> { a: "", b: 1, c: nil, d: [], e: false, f: true }.compact_blank
+=> {b: 1, f: true}
+```
+
+I might want to `compact_blank` a set of search parameters coming from the
+client before passing it into my search service:
+
+```ruby
+class BooksController < BaseController
+  def search
+    @results = SearchService.call(search_params.compact_blank)
+  end
+
+  private
+
+  def search_params
+    params.permit(...)
+  end
+end
+```