Add Remove Blank Values From A Hash as a Rails TIL

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

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+# 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
+```