Removing nil values from an array

To remove from an existing array:

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['foo', nil].compact # => ['foo']

You may also use the splat operator to ignore nil values when constructing the array:

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['foo', *nil] # => ['foo']

Removing blank values from an array

In Rails >= 6.1

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['foo', nil, '', [],  {}].compact_blank # => ['foo']

Any Rails version

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['foo', nil, '', [],  {}].reject(&:blank?) # => ['foo']

(This is actually what compact_blank does Archive .)

Note that there are bang variants of each method (compact!, compact_blank!, or reject!(&:blank?)).
They modify the array in place, so be careful not to modify an array that you received as a method argument as the caller might not expect changes to it.