Tidy Up with compact_blank

Introduced in Rails 6.1, compact_blank is an Rails ActiveSupport method that removes all blank values (like nil, empty strings, or whitespace) from Arrays, Hashes, and other Enumerable objects.

Where does it come from?

It’s not part of plain Ruby — it comes from Rails’ ActiveSupport::CoreExtensions. Rails extends core Ruby classes to add handy utility methods like this.

You need to ensure ActiveSupport is loaded — in a Rails app, it always is.

["Bhubaneswar", nil, "Pune", " ", "Hyderabad", "", "Berlin"].compact
# => ["Bhubaneswar", "Pune", "Berlin", " ", "", "Hyderabad"]

["Bhubaneswar", nil, "Pune", " ", "Hyderabad", "", "Berlin"].compact_blank
# => ["Bhubaneswar", "Pune", "Berlin", "Hyderabad"]

{name: "Debashis", address: nil, age: ""}.compact_blank
# => {name: "Debashis"}

When should you use compact_blank?

Use Case 1: Cleaning up form input data

When users submit forms with optional fields, some values might be blank strings or whitespace.

params[:tags] = ["ruby", "", "rails", "  ", nil]

# Before saving to DB or processing
clean_tags = params[:tags].compact_blank
# => ["ruby", "rails"]

Use Case 2: API payload sanitization

When working with JSON or external APIs:

data = {
  name: "Debashis",
  bio: "",
  email: nil,
  location: " "
}

data.compact_blank
# => { name: "Debashis" }

Use Case 3: Chaining for elegant one-liners

user_input.split(",").map(&:strip).compact_blank

This is cleaner than manually rejecting blank strings or checking for .nil?.

Rails adds compact_blank to Arrays, Hashes, ActiveSupport::HashWithIndifferentAccess, and any Enumerable that includes ActiveSupport extensions.

Whether you’re tidying up arrays, hashes, or any enumerable in Rails, reach for compact_blank and let Rails do the heavy lifting.