method

pluck

v3.2.13 - Show latest stable - Class: ActiveRecord::Calculations

pluck(column_name)

public

This method is designed to perform select by a single column as direct SQL query Returns Array with values of the specified column name The values has same data type as column.

Examples:

Person.pluck(:id) # SELECT people.id FROM people
Person.uniq.pluck(:role) # SELECT DISTINCT role FROM people
Person.where(:confirmed => true).limit(5).pluck(:id)

# File activerecord/lib/active_record/relation/calculations.rb, line 179
    def pluck(column_name)
      if column_name.is_a?(Symbol) && column_names.include?(column_name.to_s)
        column_name = "#{connection.quote_table_name(table_name)}.#{connection.quote_column_name(column_name)}"
      else
        column_name = column_name.to_s
      end

      relation = clone
      relation.select_values = [column_name]
      klass.connection.select_all(relation.arel).map! do |attributes|
        klass.type_cast_attribute(attributes.keys.first, klass.initialize_attributes(attributes))
      end
    end

1Note

Text improvement

xlembouras · Mar 10, 2021

The statement about not loading a bunch of records is correct because pluck returns an Array of values, not a ActiveRecord::Relation or an Array of Records.

The exact wording though may be:

"...without retrieving from the database unused columns or loading a bunch of records just to grab the attributes you want"

pluck

1Note

Text improvement

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