Add Get Specific Values From Hashes And Arrays as a Ruby TIL

ruby/get-specific-values-from-hashes-and-arrays.md

@@ -0,0 +1,44 @@
+# Get Specific Values From Hashes And Arrays
+
+Ruby defines a `#values_at` method on both `Hash` and `Array` that can be used
+to grab multiple values from an instance of either of those structures.
+
+Here is an example of grabbing values by key (if they exist) from a hash.
+
+```ruby
+> hash = {one: :two, hello: "world", four: 4}
+=> {one: :two, hello: "world", four: 4}
+> hash.values_at(:one, :four, :three)
+=> [:two, 4, nil]
+```
+
+And here is an example of grabbing values at specific indexes from an array, if
+those indexes exist.
+
+```ruby
+> arr = [:a, :b, :c, :d, :e]
+=> [:a, :b, :c, :d, :e]
+> arr.values_at(0, 3, 6)
+=> [:a, :d, nil]
+```
+
+Notice that in both cases, `nil` is returned for a key or index that doesn't
+exist.
+
+What I like about this method is that in a single call I can grab multiple
+named (or indexed) values and get a single array result with those values.
+
+One way I might use this with a JSON response from an API request could look
+like this:
+
+```ruby
+resp = client.getSomeData(id: 123)
+
+[status, body] = resp.values_at("status", "body")
+
+if status == 200
+  puts body
+end
+```
+
+[source](https://docs.ruby-lang.org/en/3.4/Hash.html#method-i-values_at)