When we have an enumerable full of hashes or hash-like values, pluck is a lovely shortcut for extracting one or more keys.

repos = [
  { "name" => "ruby", "stars" => 225_000 },
  { "name" => "rails", "stars" => 57_000 }
]

repos.pluck("name")
# => ["ruby", "rails"]

repos.pluck("name", "stars")
# => [["ruby", 225000], ["rails", 57000]]
      

const repos = [
  { name: "ruby", stars: 225000 },
  { name: "rails", stars: 57000 }
];

repos.map((repo) => repo.name);
// => ["ruby", "rails"]

repos.map((repo) => [repo.name, repo.stars]);
// => [["ruby", 225000], ["rails", 57000]]
      

Pluck can also be used as a drop-in replacement for map(&:method_name), but since it also works through [], applying it to arrays of hashes is where it really shines.

History

Enumerable#pluck was added to ActiveSupport in Rails 5.0.0, released in 2016.

This expanded on the already existing pluck method in Active Record, released a few years prior, which fetches specific columns from the database.