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

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.

> 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.

> 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:

resp = client.getSomeData(id: 123)

[status, body] = resp.values_at("status", "body")

if status == 200
  puts body
end

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