instance method `to_param`

Ruby on Rails 8.1.2

Since v4.1.16

Available in: v4.1.16 v4.2.9 v5.2.8.1 v6.0.6 v6.1.7.10 v7.0.10 v7.1.6 v7.2.3 v8.0.4 v8.1.2

Compare with:

to_param(method_name = nil)

Defines your model’s to_param method to generate “pretty” URLs using method_name, which can be any attribute or method that responds to to_s.

class User < ActiveRecord::Base
  to_param :name
end

user = User.find_by(name: 'Fancy Pants')
user.id         # => 123
user_path(user) # => "/users/123-fancy-pants"

Values longer than 20 characters will be truncated. The value is truncated word by word.

user = User.find_by(name: 'David Heinemeier Hansson')
user.id         # => 125
user_path(user) # => "/users/125-david-heinemeier"

Because the generated param begins with the record’s id, it is suitable for passing to find. In a controller, for example:

params[:id]               # => "123-fancy-pants"
User.find(params[:id]).id # => 123

Parameters

method_name opt = nil

Source

# File activerecord/lib/active_record/integration.rb, line 147
      def to_param(method_name = nil)
        if method_name.nil?
          super()
        else
          define_method :to_param do
            if (default = super()) &&
                 (result = send(method_name).to_s).present? &&
                   (param = result.squish.parameterize.truncate(20, separator: /-/, omission: "")).present?
              "#{default}-#{param}"
            else
              default
            end
          end
        end
      end

Defined in activerecord/lib/active_record/integration.rb line 147 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveRecord::Integration::ClassMethods

Signature

Parameters