Remove nil and blank string in an array in Ruby

Question

You could do this:

arr.reject { |e| e.to_s.empty? } #=> [1, 2, "s", "d"]

Note nil.to_s => ''.

Since you want to remove both nil and empty strings, it's not a duplicate of How do I remove blank elements from an array?

You want to use .reject:

arr = [1, 2, 's', nil, '', 'd']
arr.reject { |item| item.nil? || item == '' }

NOTE: reject with and without bang behaves the same way as compact with and without bang: reject! and compact! modify the array itself while reject and compact return a copy of the array and leave the original intact.

If you're using Rails, you can also use blank?. It was specifically designed to work on nil, so the method call becomes:

arr.reject { |item| item.blank? }

I tend to do:

arr = [1, 2, 's', nil, '', 'd']
arr.reject(&:blank?)

returns:

=> [1, 2, "s", "d"]

arr.reject(&:blank?)

Just use this, no need to anything else.

You can also use - to remove all nil and '' elements:

arr -= [nil, '']
#=> [1, 2, "s", "d"]

Demonstration

Or compact and reject with shortcut (in case you are not using Rails where you can just use arr.reject(&:blank?) ):

arr = arr.compact.reject(&''.method(:==))
#=> [1, 2, "s", "d"]

Demonstration

compact_blank (Rails 6.1+)

If you are using Rails (or a standalone ActiveSupport), starting from version 6.1, there is a compact_blank method which removes blank values from arrays.

It uses Object#blank? under the hood for determining if an item is blank.

[1, 2, 's', nil, '', 'd'].compact_blank
# => [1, 2, 's', 'd']

[1, "", nil, 2, " ", [], {}, false, true].compact_blank
# => [1, 2, true]

Here is a link to the docs and a link to the relative PR.

A destructive variant is also available. See Array#compact_blank!.