How to ensure a variable is an array in Ruby

While developing active_model_pusher I had to dive into the pusher-gem source code.

Seeing the following code reminded me that not all developers know about a useful trick that makes it easy to ensure a variable is an array.

Here's the offending code:

# lib/pusher/client.rb
def trigger_params(channels, event_name, data, params)
  channels = [channels] if channels.kind_of?(String)
  # ..
end

Instead of doing this check for Strings specifically, you can ensure your variable will be an array by calling Array(variable). Here's how the refactored code will look:

channels = Array(channels)

There is one case you should be aware of:

Array({key: :value}) # [[:key, :value]]

If you don't want you hash to be converted to an array and you are using Rails, there is an almost identical method Array.wrap method, which behaves a bit differently:

Array.wrap({key: :value}) # [{key: :value}]

You can read about more differences between Array() and Array.wrap() in the documentation

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